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  • ArrayList<String> NullPointerException

    - by Carlucho
    Am trying to solve a labyrinth by DFS, using adj List to represent the vertices and edges of the graph. In total there are 12 nodes (3 rows[A,B,C] * 4 cols[0,..,3]). My program starts by saving all the vertex labels (A0,..C3), so far so good, then checks the adjacent nodes, also no problems, if movement is possible, it proceeds to create the edge, here its where al goes wrong. adjList[i].add(vList[j].label); I used the debugger and found that vList[j].label is not null it contains a correct string (ie. "B1"). The only variables which show null are in adjList[i], which leads me to believe i have implemented it wrongly. this is how i did it. public class GraphList { private ArrayList<String>[] adjList; ... public GraphList(int vertexcount) { adjList = (ArrayList<String>[]) new ArrayList[vertexCount]; ... } ... public void addEdge(int i, int j) { adjList[i].add(vList[j].label); //NULLPOINTEREXCEPTION HERE } ... } I will really appreaciate if anyone can point me on the right track regrading to what its going wrong... Thanks!

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  • NullPointerException with Servlet

    - by RonaDona
    I am calling a Servlet using its URL address. This is the URL I am typing http://localhost:7001/ryan/olympics?action=selectCatalog&id=1 This is the Servlet's URL for sure; if I change the address I get page not found This is the code for the Servlet. public class Servlet extends javax.servlet.http.HttpServlet implements javax.servlet.Servlet { private static final long serialVersionUID = 1L; public Servlet() { super(); } public void init(ServletConfig config) throws ServletException { System.out.println("*** initializing controller servlet."); super.init(config); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String action = request.getParameter("action"); if (action.equals("selectCatalog")) { String categoryId = request.getParameter("id"); ProductModelDAO dao4 = new ProductModelDAOImpl("jpac"); if (categoryId != null && !categoryId.trim().equals("")) { CategoryDAO dao1 = new CategoryDAOImpl("jpac"); try { Category category = dao1.getCategoryName(categoryId); request.setAttribute("category", category); } catch (Exception e) { e.printStackTrace(); } } try { @SuppressWarnings("unchecked") List<Product> products = dao4 .getProductsByCategory(categoryId); request.setAttribute("products", products); } catch (Exception e) { e.printStackTrace(); } url = "SelectCatalog.jsp"; RequestDispatcher requestDispatcher = getServletContext().getRequestDispatcher(url); requestDispatcher.forward(request, response); I get the NullPointerException pointing to the RequestDispatcher's line. Any help?

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  • java NullPointerException when parsing XML

    - by behrk2
    Hi Everyone, I keep receiving a java.lang.NullPointerException while trying to parse out the values of ths tags in the following XML sample: <?xml version="1.0" standalone="yes"?> <autocomplete> <autocomplete_item> <title short="Forrest Gump"></title> </autocomplete_item> <autocomplete_item> <title short="Forrest Landis"></title> </autocomplete_item> <autocomplete_item> <title short="Finding Forrester"></title> </autocomplete_item> <autocomplete_item> <title short="Menotti: The Medium: Maureen Forrester"></title> </autocomplete_item> </autocomplete> Here is my parsing code, can anyone see where I am going wrong? Thanks! public String parse(String element) { Document doc = null; String result = null; DocumentBuilderFactory docBuilderFactory = DocumentBuilderFactory .newInstance(); DocumentBuilder docBuilder = null; try { docBuilder = docBuilderFactory.newDocumentBuilder(); } catch (ParserConfigurationException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } docBuilder.isValidating(); try { doc = docBuilder.parse(input); } catch (SAXException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } doc.getDocumentElement().normalize(); NodeList list = doc.getElementsByTagName(element); _node = new String(); _element = new String(); for (int i = 0; i < list.getLength(); i++) { Node value = list.item(i).getChildNodes().item(0); _node = list.item(i).getNodeName(); _element = value.getNodeValue(); result = _element; SearchResults searchResults = new SearchResults(); searchResults.setTitles(result); Vector test = searchResults.getTitles(); for (int p = 0; p < test.size(); p++) { System.out.println("STUFF: " + test.elementAt(p)); } }// end for return result; }

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  • powermock : ProcessBuilder redirectErrorStream giving nullPointerException

    - by kaustubh9
    I am using powermock to mock some native command invocation using process builder. the strange thing is these test pass sometimes and fail sometimes giving a NPE. Is this a powermock issue or some gotcha in the program. the snippet of the class under test is.. public void method1(String jsonString, String filename) { try { JSONObject jObj = new JSONObject(jsonString); JSONArray jArr = jObj.getJSONArray("something"); String cmd = "/home/y/bin/perl <perlscript>.pl<someConstant>" + " -k " + <someConstant> + " -t " + <someConstant>; cmd += vmArr.getJSONObject(i).getString("jsonKey"); ProcessBuilder pb = new ProcessBuilder("bash", "-c", cmd); pb.redirectErrorStream(false); Process shell = pb.start(); shell.waitFor(); if (shell.exitValue() != 0) { throw new RuntimeException("Error in Collecting the logs. cmd="+cmd); } StringBuilder error = new StringBuilder(); InputStream iError = shell.getErrorStream(); BufferedReader bfr = new BufferedReader( new InputStreamReader(iError)); String line = null; while ((line = bfr.readLine()) != null) { error.append(line + "\n"); } if (!error.toString().isEmpty()) { LOGGER.error(error`enter code here`); } iError.close(); bfr.close(); } catch (Exception e) { throw new RuntimeException(e); } and the unit test case is .. @PrepareForTest( {.class, ProcessBuilder.class,Process.class, InputStream.class,InputStreamReader.class, BufferedReader.class} ) @Test(sequential=true) public class TestClass { @Test(groups = {"unit"}) public void testMethod() { try { ProcessBuilder prBuilderMock = createMock(ProcessBuilder.class); Process processMock = createMock(Process.class); InputStream iStreamMock = createMock(InputStream.class); InputStreamReader iStrRdrMock = createMock(InputStreamReader.class); BufferedReader bRdrMock = createMock(BufferedReader.class); String errorStr =" Error occured"; String json = <jsonStringInput>; String cmd = "/home/y/bin/perl <perlscript>.pl -k "+<someConstant>+" -t "+<someConstant>+" "+<jsonValue>; expectNew(ProcessBuilder.class, "bash", "-c", cmd).andReturn(prBuilderMock); expect(prBuilderMock.redirectErrorStream(false)).andReturn(prBuilderMock); expect(prBuilderMock.start()).andReturn(processMock); expect(processMock.waitFor()).andReturn(0); expect(processMock.exitValue()).andReturn(0); expect(processMock.getErrorStream()).andReturn(iStreamMock); expectNew(InputStreamReader.class, iStreamMock) .andReturn(iStrRdrMock); expectNew(BufferedReader.class, iStrRdrMock) .andReturn(bRdrMock); expect(bRdrMock.readLine()).andReturn(errorStr); expect(bRdrMock.readLine()).andReturn(null); iStreamMock.close(); bRdrMock.close(); expectLastCall().once(); replayAll(); <ClassToBeTested> instance = new <ClassToBeTested>(); instance.method1(json, fileName); verifyAll(); } catch (Exception e) { Assert.fail("failed while collecting log.", e); } } I get an error on execution an the test case fails.. Caused by: java.lang.NullPointerException at java.lang.ProcessBuilder.start(ProcessBuilder.java:438) Note : I do not get this error on all executions. Sometimes it passes and sometimes it fails. I am not able to understand this behavior.

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  • NullPointerException in generated JSP code calling setJspId()

    - by Dobbo
    I am trying to deploy the Duke's Bank example form the J2EE 5 tutorial on JBoss 7.1.1. I have only used (unaltered) the source, and the standard XML configuration files for deployment, part of the exercise here is to see how I might structure a JSP based project of my own. The exception I get is as follows: ERROR [[jsp]] Servlet.service() for servlet jsp threw exception: java.lang.NullPointerException at javax.faces.webapp.UIComponentClassicTagBase.setJspId(UIComponentClassicTagBase.java:1858) [jboss-jsf-api_2.1_spec-2.0.1.Final.jar:2.0.1.Final] at org.apache.jsp.main_jsp._jspx_meth_f_005fview_005f0(main_jsp.java:99) at org.apache.jsp.main_jsp._jspService(main_jsp.java:76) at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) [jbossweb-7.0.13.Final.jar:] at javax.servlet.http.HttpServlet.service(HttpServlet.java:847) [jboss-servlet-api_3.0_spec-1.0.0.Final.jar:1.0.0.Final] at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:369) [jbossweb-7.0.13.Final.jar:] at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:326) [jbossweb-7.0.13.Final.jar:] at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:253) [jbossweb-7.0.13.Final.jar:] at javax.servlet.http.HttpServlet.service(HttpServlet.java:847) [jboss-servlet-api_3.0_spec-1.0.0.Final.jar:1.0.0.Final] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:329) [jbossweb-7.0.13.Final.jar:] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:248) [jbossweb-7.0.13.Final.jar:] at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:275) [jbossweb-7.0.13.Final.jar:] at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:161) [jbossweb-7.0.13.Final.jar:] at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:397) [jbossweb-7.0.13.Final.jar:] at org.jboss.as.jpa.interceptor.WebNonTxEmCloserValve.invoke(WebNonTxEmCloserValve.java:50) [jboss-as-jpa-7.1.1.Final.jar:7.1.1.Final] at org.jboss.as.web.security.SecurityContextAssociationValve.invoke(SecurityContextAssociationValve.java:153) [jboss-as-web-7.1.1.Final.jar:7.1.1.Final] at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:155) [jbossweb-7.0.13.Final.jar:] at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) [jbossweb-7.0.13.Final.jar:] at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) [jbossweb-7.0.13.Final.jar:] at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:368) [jbossweb-7.0.13.Final.jar:] at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:877) [jbossweb-7.0.13.Final.jar:] at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:671) [jbossweb-7.0.13.Final.jar:] at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:930) [jbossweb-7.0.13.Final.jar:] at java.lang.Thread.run(Thread.java:636) [rt.jar:1.6.0_18] I have not given any JBoss configuration files, the WAR's WEB-INF part looks like this: $ jar tvf build/lib/dukebank-web.war 0 Sat Dec 15 22:00:12 GMT 2012 META-INF/ 123 Sat Dec 15 22:00:10 GMT 2012 META-INF/MANIFEST.MF 0 Sat Dec 15 22:00:12 GMT 2012 WEB-INF/ 2514 Fri Dec 14 14:29:20 GMT 2012 WEB-INF/web.xml 1348 Sat Dec 15 08:19:46 GMT 2012 WEB-INF/dukesBank.tld 7245 Sat Dec 15 08:19:46 GMT 2012 WEB-INF/faces-config.xml 2153 Sat Dec 15 08:19:46 GMT 2012 WEB-INF/tutorial-template.tld 0 Sat Dec 15 22:00:12 GMT 2012 WEB-INF/classes/... The JSP file (main.jsp) that causes this problem is: <f:view> <h:form> <jsp:include page="/template/template.jsp"/> <center> <h3><h:outputText value="#{bundle.Welcome}"/></h3> </center> </h:form> </f:view> The template file it includes: <%@ taglib uri="/WEB-INF/tutorial-template.tld" prefix="tt" %> <%@ page errorPage="/template/errorpage.jsp" %> <%@ include file="/template/screendefinitions.jspf" %> <html> <head> <title> <tt:insert definition="bank" parameter="title"/> </title> <link rel="stylesheet" type="text/css" href="stylesheet.css"> </head> <body bgcolor="#ffffff"> <tt:insert definition="bank" parameter="banner"/> <tt:insert definition="bank" parameter="links"/> </body> </html> I will refrain from coping any more files because, as I said at the start I haven't altered any of the files I have used. Many thanks for your help, Steve

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  • Not sure why I'm getting a NullPointerException when creating a Swing component

    - by Alex
    The error occurs when creating the Box object. public void drawBoard(Board board){ for(int row = 0; row < 8; row++){ for(int col = 0; col < 8; col++){ Box box = new Box(board.getSquare(col, row).getColour(), col, row); squarePanel[col][row].add(box); } } Board is given from the Game constructor here (another class): public Game() throws Throwable{ View graphics = new View(); board = new Board(); board.setDefault(); graphics.drawBoard(board); } The Board constructor looks like this: public Board(){ grid = new Square[COLUMNS][ROWS]; for(int row = 0; row < 8; row++){ for(int col = 0; col < 8; col++){ grid[col][row] = new Square(this); } } for(int row = 0; row < 8; row++){ for(int col = 0; col < 4; col++){ int odd = 2*col + 1; int even = 2*col; getSquare(odd, row).setColour(Color.BLACK); getSquare(even, row).setColour(Color.WHITE); } } } And finally the Box class: class Box extends JComponent{ Color boxColour; int col, row; public Box(Color boxColour, int col, int row){ this.boxColour = boxColour; this.col = col; this.row = row; repaint(); } public void paint(Graphics drawBox){ drawBox.setColor(boxColour); drawBox.drawRect(50*col, 50*row, 50, 50); drawBox.fillRect(50*col, 50*row, 50, 50); } } So while looping through the array, it uses the two integers as coordinates to create the Box. The coordinates are referenced and then repaint() is run. The box also gets the colour, using the two integers, from the Square in the Board class. Since the colour is already set, before the drawBoard(board) method is run, that shouldn't be a problem, right? Exception in thread "main" java.lang.NullPointerException at View.drawBoard(View.java:38) at Game.<init>(Game.java:21) at Game.main(Game.java:14) The relevant part of Square import java.awt.Color; public class Square { private Piece piece; private Board board; private Color squareColour; public Square(Board board){ this.board = board; } public void setColour(Color squareColour){ this.squareColour = squareColour; } public Color getColour(){ return squareColour; }

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  • NullPointerException, Collections not storing data?

    - by Elliott
    Hi there, I posted this question earlier but not with the code in its entirety. The coe below also calls to other classes Background and Hydro which I have included at the bottom. I have a Nullpointerexception at the line indicate by asterisks. Which would suggest to me that the Collections are not storing data properly. Although when I check their size they seem correct. Thanks in advance. PS: If anyone would like to give me advice on how best to format my code to make it readable, it would be appreciated. Elliott package exam0607; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.net.URL; import java.util.Collection; import java.util.Scanner; import java.util.Vector; import exam0607.Hydro; import exam0607.Background;// this may not be necessary???? FIND OUT public class HydroAnalysis { public static void main(String[] args) { Collection hydroList = null; Collection backList = null; try{hydroList = readHydro("http://www.hep.ucl.ac.uk/undergrad/3459/exam_data/2006-07/final/hd_data.dat");} catch (IOException e){ e.getMessage();} try{backList = readBackground("http://www.hep.ucl.ac.uk/undergrad/3459/exam_data/2006-07/final/hd_bgd.dat"); //System.out.println(backList.size()); } catch (IOException e){ e.getMessage();} for(int i =0; i <=14; i++ ){ String nameroot = "HJK"; String middle = Integer.toString(i); String hydroName = nameroot + middle + "X"; System.out.println(hydroName); ALGO_1(hydroName, backList, hydroList); } } public static Collection readHydro(String url) throws IOException { URL u = new URL(url); InputStream is = u.openStream(); InputStreamReader isr = new InputStreamReader(is); BufferedReader b = new BufferedReader(isr); String line =""; Collection data = new Vector(); while((line = b.readLine())!= null){ Scanner s = new Scanner(line); String name = s.next(); System.out.println(name); double starttime = Double.parseDouble(s.next()); System.out.println(+starttime); double increment = Double.parseDouble(s.next()); System.out.println(+increment); double p = 0; double nterms = 0; while(s.hasNextDouble()){ p = Double.parseDouble(s.next()); System.out.println(+p); nterms++; System.out.println(+nterms); } Hydro SAMP = new Hydro(name, starttime, increment, p); data.add(SAMP); } return data; } public static Collection readBackground(String url) throws IOException { URL u = new URL(url); InputStream is = u.openStream(); InputStreamReader isr = new InputStreamReader(is); BufferedReader b = new BufferedReader(isr); String line =""; Vector data = new Vector(); while((line = b.readLine())!= null){ Scanner s = new Scanner(line); String name = s.next(); //System.out.println(name); double starttime = Double.parseDouble(s.next()); //System.out.println(starttime); double increment = Double.parseDouble(s.next()); //System.out.println(increment); double sum = 0; double p = 0; double nterms = 0; while((s.hasNextDouble())){ p = Double.parseDouble(s.next()); //System.out.println(p); nterms++; sum += p; } double pbmean = sum/nterms; Background SAMP = new Background(name, starttime, increment, pbmean); //System.out.println(SAMP); data.add(SAMP); } return data; } public static void ALGO_1(String hydroName, Collection backgs, Collection hydros){ //double aMin = Double.POSITIVE_INFINITY; //double sum = 0; double intensity = 0; double numberPN_SIG = 0; double POSITIVE_PN_SIG =0; //int numberOfRays = 0; for(Hydro hd: hydros){ System.out.println(hd.H_NAME); for(Background back : backgs){ System.out.println(back.H_NAME); if(back.H_NAME.equals(hydroName)){//ERROR HERE double PN_SIG = Math.max(0.0, hd.PN - back.PBMEAN); numberPN_SIG ++; if(PN_SIG 0){ intensity += PN_SIG; POSITIVE_PN_SIG ++; } } } double positive_fraction = POSITIVE_PN_SIG/numberPN_SIG; if(positive_fraction < 0.5){ System.out.println( hydroName + "is faulty" ); } else{System.out.println(hydroName + "is not faulty");} System.out.println(hydroName + "has instensity" + intensity); } } } THE BACKGROUND CLASS package exam0607; public class Background { String H_NAME; double T_START; double DT; double PBMEAN; public Background(String name, double starttime, double increment, double pbmean) { name = H_NAME; starttime = T_START; increment = DT; pbmean = PBMEAN; }} AND THE HYDRO CLASS public class Hydro { String H_NAME; double T_START; double DT; double PN; public double n; public Hydro(String name, double starttime, double increment, double p) { name = H_NAME; starttime = T_START; increment = DT; p = PN; } }

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  • NullPointerException when trying to add an object to a PriorityQueue

    - by meagan
    i keep getting a null pointer exception when trying to add an object to a priority queue i initialize the queue: private PriorityQueue<NodeObject> nodes; and here i try to add to it: NodeObject childNode = new NodeObject(child, 1); nodes.add(childNode); why doesn't this work? i know my NodeObject is not null because i create it right before i add it.

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  • NullPointerException when thying to add an object to a PriorityQueue

    - by meagan
    i keep getting a null pointer exception when trying to add an object to a priority queue i initialize the queue: private PriorityQueue<NodeObject> nodes; and here i try to add to it: NodeObject childNode = new NodeObject(child, 1); nodes.add(childNode); why doesn't this work? i know my NodeObject is not null because i create it right before i add it.

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  • NullPointerException Java help

    - by KP65
    Hello guys. I've been tearing my hair out the past few hours trying to solve this problem. Every time I click on a JButton which should open a JFrame(And it does), i get a stacktrace saying I have a null point exception at these bits of code: In class A i have: aButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { B instanceofB = new B(userSession.getBalance()); }); and Class B super.getSomeBtn().setVisible(false); This is where the stacktrace says the errors are in the two above sections. I have a line exactly the same as the one above in Class B and it works fine? Really stuck here!

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  • Java NullPointerException In the constructor's class

    - by AndreaF
    I have made a Java class where I have defined a constructor and some methods but I get a NullPointer Exception, and I don't know how I could fix It. public class Job { String idJob; int time; int timeRun; Job j1; List<Job> startBeforeStart; List<Job> restricted; Job(String idJob, int time){ this.idJob=idJob; this.time=time; } public boolean isRestricted() { return restricted.size() != 0; } public void startsBeforeStartOf(Job job){ startBeforeStart.add(job); job.restricted.add(this); } public void startsAfterStartOf(Job job){ job.startsBeforeStartOf(this); } public void checkRestrictions(){ if (!isRestricted()){ System.out.println("+\n"); } else{ Iterator<Job> itR = restricted.iterator(); while(itR.hasNext()){ Job j1 = itR.next(); if(time>timeRun){ System.out.println("-\n"); time--; } else { restricted.remove(j1); } } } } @Override public boolean equals(Object obj) { return obj instanceof Job && ((Job) obj).idJob.equals(idJob); } public void run() { timeRun++; } } PS Looking in a forum a user says that to fix the error I should make an ArrayList inside the constructor (without modify the received parameters that should remain String id and int time), but I haven't understand what He mean.

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  • NullPointerException on TextView

    - by Stephen Adipradhana
    i get a null pointer exception and the program crash on each time i want to update the highscore text using setText(). what causes this problem? this code is when i set my layout, the layout is a part of the gameView using opengl, and i put the highscore textview on the upper left corner public void onCreate(Bundle savedInstanceState) { SFEngine.display = ((WindowManager)getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();//ambl ukuran width height layar super.onCreate(savedInstanceState); gameView = new SFGameView(this); gameView.setLayoutParams(new RelativeLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT)); RelativeLayout layout = new RelativeLayout(this); layout.setLayoutParams(new FrameLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT)); TextView textBox = new TextView(this); textBox.setId(1); textBox.setText("HIGH SCORE"); textBox.setBackgroundColor(Color.BLUE); textBox.setWidth(SFEngine.display.getWidth()/2); textBox.setHeight(50); Button pauseButton = new Button(this); pauseButton.setText("PAUSE"); pauseButton.setHeight(50); pauseButton.setWidth(SFEngine.display.getWidth()/2); pauseButton.setOnTouchListener(new OnTouchListener(){ public boolean onTouch(View v, MotionEvent e) { //pause game SFEngine.isPlaying = false; Intent i1 = new Intent(SFGames.this, pause.class); gameView.onPause(); startActivityForResult(i1,0);//hrs pk result soalny mw blk lg return true; } }); RelativeLayout.LayoutParams lp_pause = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT); RelativeLayout.LayoutParams lp_hs = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT); lp_hs.addRule(RelativeLayout.ALIGN_PARENT_LEFT); lp_pause.addRule(RelativeLayout.ALIGN_PARENT_TOP); lp_pause.addRule(RelativeLayout.ALIGN_PARENT_RIGHT); textBox.setLayoutParams(lp_hs); pauseButton.setLayoutParams(lp_pause); layout.addView(gameView); layout.addView(textBox); layout.addView(pauseButton); setContentView(layout); and here is the setText code public boolean onTouchEvent (MotionEvent event){//buat nerima input user if(!SFEngine.isPlaying){ finish(); } textBox.setText("High Score :" + SFEngine.score);//here is the source of the prob .....

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  • Java: ListA.addAll(ListB) fires NullPointerException?

    - by HH
    The err part is Capitalized in the code, it also comes in foreaching. Because of the abstract list, it cannot be initialized, declaration is in a static field. The lists have the same type. import java.util.*; public class Test { public static final List<String> highPrio = Arrays.asList("*","/"); public static List<String> ops; public static void main(String[] args) { //ERROR HERE, why do it throw nullPointer? ops.addAll(highPrio); for(String s : ops) { System.out.println(s); } } }

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  • Is it a bad idea if equals(null) throws NullPointerException instead?

    - by polygenelubricants
    The contract of equals with regards to null, is as follows: For any non-null reference value x, x.equals(null) should return false. This is rather peculiar, because if o1 != null and o2 == null, then we have: o1.equals(o2) // returns false o2.equals(o1) // throws NullPointerException The fact that o2.equals(o1) throws NullPointerException is a good thing, because it alerts us of programmer error. And yet, that error would not be catched if for various reasons we just switched it around to o1.equals(o2), which would just "silently fail" instead. So the questions are: Why is it a good idea that o1.equals(o2) should return false instead of throwing NullPointerException? Would it be a bad idea if wherever possible we rewrite the contract so that anyObject.equals(null) always throw NullPointerException instead?

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  • SpringMvc java.lang.NullPointerException When Posting Form To Server [closed]

    - by dev_darin
    I have a form with a user name field on it when i tab out of the field i use a RESTFUL Web Service that makes a call to a handler method in the controller. The method makes a call to a DAO class that checks the database if the user name exists. This works fine, however when the form is posted to the server i call the same exact function i would call in the handler method however i get a java.lang.NullPointerException when it accesses the class that makes a call to the DAO object. So it does not even access the DAO object the second time. I have exception handlers around the calls in all my classes that makes calls. Any ideas as to whats happening here why i would get the java.lang.NullPointerException the second time the function is called.Does this have anything to do with Spring instantiating DAO classes using a Singleton method or something to that effect? What can be done to resolve this? This is what happens the First Time The Method is called using the Web Service(this is suppose to happen): 13011 [http-8084-2] INFO com.crimetrack.jdbc.JdbcOfficersDAO - Inside jdbcOfficersDAO 13031 [http-8084-2] DEBUG org.springframework.jdbc.core.JdbcTemplate - Executing prepared SQL query 13034 [http-8084-2] DEBUG org.springframework.jdbc.core.JdbcTemplate - Executing prepared SQL statement [SELECT userName FROM crimetrack.tblofficers WHERE userName = ?] 13071 [http-8084-2] DEBUG org.springframework.jdbc.datasource.DataSourceUtils - Fetching JDBC Connection from DataSource 13496 [http-8084-2] DEBUG org.springframework.jdbc.core.StatementCreatorUtils - Setting SQL statement parameter value: column index 1, parameter value [adminz], value class [java.lang.String], SQL type unknown 13534 [http-8084-2] DEBUG org.springframework.jdbc.datasource.DataSourceUtils - Returning JDBC Connection to DataSource 13537 [http-8084-2] INFO com.crimetrack.jdbc.JdbcOfficersDAO - No username was found in exception 13537 [http-8084-2] INFO com.crimetrack.service.ValidateUserNameManager - UserName :adminz does NOT exist The Second time When The Form Is 'Post' and a validation method handles the form and calls the same method the web service would call: 17199 [http-8084-2] INFO com.crimetrack.service.OfficerRegistrationValidation - UserName is not null so going to check if its valid for :adminz 17199 [http-8084-2] INFO com.crimetrack.service.OfficerRegistrationValidation - User Name in try.....catch block is adminz 17199 [http-8084-2] INFO com.crimetrack.service.ValidateUserNameManager - Inside Do UserNameExist about to validate with username : adminz 17199 [http-8084-2] INFO com.crimetrack.service.ValidateUserNameManager - UserName :adminz EXCEPTION OCCURED java.lang.NullPointerException ValidateUserNameManager.java public class ValidateUserNameManager implements ValidateUserNameIFace { private OfficersDAO officerDao; private final Logger logger = Logger.getLogger(getClass()); public boolean DoesUserNameExist(String userName) throws Exception { logger.info("Inside Do UserNameExist about to validate with username : " + userName); try{ if(officerDao.OfficerExist(userName) == true){ logger.info("UserName :" + userName + " does exist"); return true; }else{ logger.info("UserName :" + userName + " does NOT exist"); return false; } }catch(Exception e){ logger.info("UserName :" + userName + " EXCEPTION OCCURED " + e.toString()); return false; } } /** * @return the officerDao */ public OfficersDAO getOfficerDao() { return officerDao; } /** * @param officerdao the officerDao to set */ public void setOfficerDao(OfficersDAO officerDao) { this.officerDao = officerDao; } } JdbcOfficersDAO.java public boolean OfficerExist(String userName){ String dbUserName; try{ logger.info("Inside jdbcOfficersDAO"); String sql = "SELECT userName FROM crimetrack.tblofficers WHERE userName = ?"; try{ dbUserName = (String)getJdbcTemplate().queryForObject(sql, new Object[]{userName},String.class); logger.info("Just Returned from database"); }catch(Exception e){ logger.info("No username was found in exception"); return false; } if(dbUserName == null){ logger.info("Database did not find any matching records"); } logger.info("after JdbcTemplate"); if (dbUserName.equals(userName)) { logger.info("User Name Exists"); return true; }else{ logger.info("User Name Does NOT Exists"); return false; } }catch(Exception e){ logger.info("Exception Message in JdbcOfficersDAO is "+e.getMessage()); return false; } } OfficerRegistrationValidation.java public class OfficerRegistrationValidation implements Validator{ private final Logger logger = Logger.getLogger(getClass()); private ValidateUserNameManager validateUserNameManager; public boolean supports(Class<?> clazz) { return Officers.class.equals(clazz); } public void validate(Object target, Errors errors) { Officers officer = (Officers) target; if (officer.getUserName() == null){ errors.rejectValue("userName", "userName.required"); }else{ String userName = officer.getUserName(); logger.info("UserName is not null so going to check if its valid for :" + userName); try { logger.info("User Name in try.....catch block is " + userName); if (validateUserNameManager.DoesUserNameExist(userName)== true){ errors.rejectValue("userName", "userName.exist"); } } catch (Exception e) { logger.info("Error Occured When validating UserName"); errors.rejectValue("userName", "userName.error"); } } if(officer.getPassword()== null){ errors.rejectValue("password", "password.required"); } if(officer.getPassword2()== null){ errors.rejectValue("password2", "password2.required"); } if(officer.getfName() == null){ errors.rejectValue("fName","fName.required"); } if(officer.getlName() == null){ errors.rejectValue("lName", "lName.required"); } if (officer.getoName() == null){ errors.rejectValue("oName", "oName.required"); } if (officer.getEmailAdd() == null){ errors.rejectValue("emailAdd", "emailAdd.required"); } if (officer.getDob() == null){ errors.rejectValue("dob", "dob.required"); } if (officer.getGenderId().equals("A")){ errors.rejectValue("genderId","genderId.required"); } if(officer.getDivisionNo() == 1){ errors.rejectValue("divisionNo", "divisionNo.required"); } if(officer.getPositionId() == 1){ errors.rejectValue("positionId", "positionId.required"); } if (officer.getStartDate() == null){ errors.rejectValue("startDate","startDate.required"); } if(officer.getEndDate() == null){ errors.rejectValue("endDate","endDate.required"); } logger.info("The Gender ID is " + officer.getGenderId().toString()); if(officer.getPhoneNo() == null){ errors.rejectValue("phoneNo", "phoneNo.required"); } } /** * @return the validateUserNameManager */ public ValidateUserNameManager getValidateUserNameManager() { return validateUserNameManager; } /** * @param validateUserNameManager the validateUserNameManager to set */ public void setValidateUserNameManager( ValidateUserNameManager validateUserNameManager) { this.validateUserNameManager = validateUserNameManager; } } Update Error Log using Logger.Error("Message", e): 39024 [http-8084-2] INFO com.crimetrack.service.OfficerRegistrationValidation - UserName is not null so going to check if its valid for :adminz 39025 [http-8084-2] INFO com.crimetrack.service.OfficerRegistrationValidation - User Name in try.....catch block is adminz 39025 [http-8084-2] ERROR com.crimetrack.service.OfficerRegistrationValidation - Message java.lang.NullPointerException at com.crimetrack.service.OfficerRegistrationValidation.validate(OfficerRegistrationValidation.java:47) at org.springframework.validation.DataBinder.validate(DataBinder.java:725) at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.doBind(HandlerMethodInvoker.java:815) at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveHandlerArguments(HandlerMethodInvoker.java:367) at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:171) at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:436) at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:424) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882) at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:789) at javax.servlet.http.HttpServlet.service(HttpServlet.java:637) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:602) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) at java.lang.Thread.run(Unknown Source) 39025 [http-8084-2] INFO com.crimetrack.service.OfficerRegistrationValidation - Error Occured When validating UserName

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  • Is it standard behavior for this code to throw a NullPointerException?

    - by Eric
    I've had a big problem in some library code, which I've pinned down to a single statement: System.out.println((String) null); Ok, the code doesn't actually look like that, but it certainly calls println with a null argument. Doing this causes my whole applicaio to throw an unexpected NullPointerException. In general, should println throw this exception under that circumstance, or is this non-standard behavior due to a poor implementation of the out instance?

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  • Why i am getting NullPointerException for this btree method??

    - by user306540
    hi, i am writing code for btree algorithms. i am getting NullPointerException . why???? please somebody help me...! public void insertNonFull(BPlusNode root,BPlusNode parent,String key) { int i=0; BPlusNode child=new BPlusNode(); BPlusNode node=parent; while(true) { i=node.numKeys-1; if(node.leaf) { while(i>=0 && key.compareTo(node.keys[i])<0) { node.keys[i+1]=node.keys[i]; i--; } node.keys[i+1]=key; node.numKeys=node.numKeys+1; } else { while(i>=0 && key.compareTo(node.keys[i])<0) { i--; } } i++; child=node.pointers[i]; if(child!=null && child.numKeys==7) { splitChild(root,node,i,child); if(key.compareTo(node.keys[i])>0) { i++; } } node=node.pointers[i]; } }

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  • How to enforce jsf to create new instance of bean instead of throwing NullPointerException?

    - by Roman
    I'm almost sure that I do something wrong and thus the question's title is a bit incorrect. I have a form with several fields for creating a new User-objects (fields like login, password, birthday etc). And I have 2 buttons - Cancel and Create. I didn't finish Create yet :) , but when I press Cancel I see NullPointerException. Here is simplified code: <f:view> <h:form> <h:panelGroup layout="block"> <h:inputText id="add_login" value="#{userSupport.user.login}"/> <h:inputSecret id="add_password" value="#{userSupport.user.password}"/> <h:inputText id="add_name" value="#{userSupport.user.name}"/> <h:inputText id="add_surname" value="#{userSupport.user.surname}"/> <h:commandButton value="Cancel" action="cancel"/> </h:panelGroup> </h:form> </f:view> UserSupport class has field user with getter and setter and some other methods. It's a Spring bean with Session scope. When I press cancel, I see NPE because jsf tries to save values from inputs in user-object, but user-object is null. What is the correct way of doing this?

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  • Java.lang.NullPointerException when using retreived Image (Unless method is used statically!)

    - by Emdiesse
    Hi there, This has been doing my head in all day and I have finally decided to resort to asking for help! In my MIDLet I have an instance of the java class ImageFetcher called anImg. Also within my MIDLet I have a command that simply say's fetch, a CommandListener that when detects fetch was clicked runs the function below. This function should simply run public getImage() from the anImg instance of class ImageFetcher which returns an image and then appends/sets this Image onto the form on the display. (You may recognise the getImage() function from the Nokia JavaME Wiki!!!) Instead of any image being displayed this is written to the output terminal in netbeans: Msg: Java.lang.NullPointerException HOWEVER, If I change public getImage() to public static getImage() and replace anImg.getImage() with ImageFetcher.getImage() the image is successfully displayed!!! Thank you for your replies on this issue :) I look forward to going my hair back after this ordeal! FetchImageApp.java ... ... ... private doThis(){ try { Image im; if ((im = anImg.getImage()) != null) { ImageItem ii = new ImageItem(null, im, ImageItem.LAYOUT_DEFAULT, null); // If there is already an image, set (replace) it if (form.size() != 0) { form.set(0, ii); } else // Append the image to the empty form { form.append(ii); } } else { form.append("Unsuccessful download."); } // Display the form with the image display.setCurrent(form); } catch (Exception e) { System.err.println("Msg: " + e.toString()); } } ... ... ... ImageFetcher.java ... ... ... /*-------------------------------------------------- * Open connection and download png into a byte array. *-------------------------------------------------*/ public Image getImage() throws IOException { String url = "http://kenai.com/attachments/wiki_images/chessgame/java-duke-logo.png"; ContentConnection connection = (ContentConnection) Connector.open(url); // * There is a bug in MIDP 1.0.3 in which read() sometimes returns // an invalid length. To work around this, I have changed the // stream to DataInputStream and called readFully() instead of read() // InputStream iStrm = connection.openInputStream(); DataInputStream iStrm = connection.openDataInputStream(); ByteArrayOutputStream bStrm = null; Image im = null; try { // ContentConnection includes a length method byte imageData[]; int length = (int) connection.getLength(); if (length != -1) { imageData = new byte[length]; // Read the png into an array // iStrm.read(imageData); iStrm.readFully(imageData); } else // Length not available... { bStrm = new ByteArrayOutputStream(); int ch; while ((ch = iStrm.read()) != -1) { bStrm.write(ch); } imageData = bStrm.toByteArray(); bStrm.close(); } // Create the image from the byte array im = Image.createImage(imageData, 0, imageData.length); } finally { // Clean up if (iStrm != null) { iStrm.close(); } if (connection != null) { connection.close(); } if (bStrm != null) { bStrm.close(); } } return (im == null ? null : im); } ... ... ...

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  • Why do I get a nullpointerexception at line ds.getPort in class L1?

    - by Fred
    import java.awt.; import java.awt.event.; import javax.swing.; import java.io.; import java.net.; import java.util.; public class Draw extends JFrame { /* * Socket stuff */ static String host; static int port; static int localport; DatagramSocket ds; Socket socket; Draw d; Paper p = new Paper(ds); public Draw(int localport, String host, int port) { d = this; this.localport = localport; this.host = host; this.port = port; try { ds = new DatagramSocket(localport); InetAddress ia = InetAddress.getByName(host); System.out.println("Attempting to connect DatagramSocket. Local port " + localport + " , foreign host " + host + ", foreign port " + port + "..."); ds.connect(ia, port); System.out.println("Success, ds.localport: " + ds.getLocalPort() + ", ds.port: " + ds.getPort() + ", address: " + ds.getInetAddress()); Reciever r = new Reciever(ds); r.start(); } catch (Exception e) { e.printStackTrace(); } setDefaultCloseOperation(EXIT_ON_CLOSE); getContentPane().add(p, BorderLayout.CENTER); setSize(640, 480); setVisible(true); } public static void main(String[] args) { int x = 0; for (String s : args){ if (x==0){ localport = Integer.parseInt(s); x++; } else if (x==1){ host = s; x++; } else if (x==2){ port = Integer.parseInt(s); } } Draw d = new Draw(localport, host, port); } } class Paper extends JPanel { DatagramSocket ds; private HashSet hs = new HashSet(); public Paper(DatagramSocket ds) { this.ds=ds; setBackground(Color.white); addMouseListener(new L1(ds)); addMouseMotionListener(new L2()); } public void paintComponent(Graphics g) { super.paintComponent(g); g.setColor(Color.black); Iterator i = hs.iterator(); while(i.hasNext()) { Point p = (Point)i.next(); g.fillOval(p.x, p.y, 2, 2); } } private void addPoint(Point p) { hs.add(p); repaint(); } class L1 extends MouseAdapter { DatagramSocket ds; public L1(DatagramSocket ds){ this.ds=ds; } public void mousePressed(MouseEvent me) { addPoint(me.getPoint()); Point p = me.getPoint(); String message = Integer.toString(p.x) + " " + Integer.toString(p.y); System.out.println(message); try{ byte[] data = message.getBytes("UTF-8"); //InetAddress ia = InetAddress.getByName(ds.host); String convertedMessage = new String(data, "UTF-8"); System.out.println("The converted string is " + convertedMessage); DatagramPacket dp = new DatagramPacket(data, data.length); System.out.println(ds.getPort()); //System.out.println(message); //System.out.println(ds.toString()); //ds.send(dp); /*System.out.println("2Sending a packet containing data: " +data +" to " + ia + ":" + d.port + "...");*/ } catch (Exception e){ e.printStackTrace(); } } } class L2 extends MouseMotionAdapter { public void mouseDragged(MouseEvent me) { addPoint(me.getPoint()); Point p = me.getPoint(); String message = Integer.toString(p.x) + " " + Integer.toString(p.y); //System.out.println(message); } } } class Reciever extends Thread{ DatagramSocket ds; byte[] buffer; Reciever(DatagramSocket ds){ this.ds = ds; buffer = new byte[65507]; } public void run(){ try { DatagramPacket packet = new DatagramPacket(buffer, buffer.length); while(true){ try { ds.receive(packet); String s = new String(packet.getData()); System.out.println(s); } catch (Exception e) { e.printStackTrace(); } } } catch (Exception e) { e.printStackTrace(); } } }

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  • Error Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException [migrated]

    - by user134212
    I'm new here. I'm learning how to program on java and I have a problem with my code. I really have no clue why my code is not working. I think my mistake may be here, but I'm not quite sure. m3 = new Matriz(ren2,col2); btSumar.addActionListener(new ActionListener() { Matriz m3;//(ren2,col2); public void actionPerformed(ActionEvent e) { m3 = new Matriz(ren2,col2); if(ventanaAbierta==true) { try { crearMat.SUMA(m1,m2); } catch(Exception nul) { System.out.println(nul); } } else { JOptionPane.showMessageDialog(null,"Ya se realizo la suma"); } } }); My Complete code import java.awt.*; import javax.swing.*; import javax.swing.BorderFactory; import javax.swing.border.Border; import java.awt.event.*; import java.awt.*; import java.io.*; import java.util.*; public class Practica2 { private int opcion,ren2,col2; private JFrame ventana,ventanaPrintMatriz; private JPanel panel,panel2; private Border borderRed2,borderBlue2,borderGreen2,borderGreen4; private Color red,green,blue,white,black; private Font Verdana14,ArialBlack18; private JLabel labelTitulo; public JButton btSalir,btSumar,btRestar,btMultiplica,btTranspuesta,btCrear; private ImageIcon suma,resta,multi,crear,salir,trans; private boolean ventanaAbierta = false; private static ValidacionesMatrices valida; private static Operaciones operacion; private static Matriz m1,m2,m3; private static ImprimirMatriz printMat; public Practica2() { panel = new JPanel(); panel.setLayout(null); ventana = new JFrame("Operaciones con Matrices"); ventana.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE); ventana.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { //Sale del programa System.exit(0); } }); ventana.setContentPane(panel); ventana.setVisible(true); ventana.setResizable(false); ventana.setBounds(150,150,300,380); //ventana.setBounds(0,0,650,650); } public void inicializarComponentes() { panel2 = new JPanel(); panel2.setLayout(null); labelTitulo = new JLabel("Practica #2"); suma = new ImageIcon("suma1.png"); resta = new ImageIcon("resta1.png"); multi = new ImageIcon("multi1.png"); trans = new ImageIcon("trans2.png"); crear = new ImageIcon("crear1.png"); salir = new ImageIcon("salir1.png"); btTranspuesta = new JButton("Transpuesta",trans); btMultiplica = new JButton("Multiplica",multi); btRestar = new JButton("Restar",resta); btSumar = new JButton("Sumar",suma); btCrear = new JButton("Crear",crear); btSalir = new JButton("Salir",salir); //Tipo de letra ArialBlack18 = new Font("Arial Black",Font.BOLD,18); //Color green = new Color(0,255,0); //Formato labelTitulo labelTitulo.setBounds(80,-60,200,150); labelTitulo.setFont(ArialBlack18); labelTitulo.setForeground(blue); labelTitulo.setVisible(true); //Formato de CrearMatriz btCrear.setBounds(80,50,130,30); btCrear.setToolTipText("Crea una matriz"); //Formato de Muliplica btMultiplica.setBounds(80,100,130,30); btMultiplica.setToolTipText("Mat[A] * Mat[B]"); //Formato de botonRestar btRestar.setBounds(80,150,130,30); btRestar.setToolTipText("Mat[A] - Mat[B]"); //Formato del botonSumar btSumar.setBounds(80,200,130,30); btSumar.setToolTipText("Mat[A] + Mat[B]"); //Formato de Transpuesta btTranspuesta.setBounds(80,250,130,30); btTranspuesta.setToolTipText("Mat[A]^-1"); //Formato del botonSalir btSalir.setBounds(80,300,130,30); //Agregando componentes al panel1 panel2.add(labelTitulo); panel2.add(btMultiplica); panel2.add(btCrear); panel2.add(btRestar); panel2.add(btSumar); panel2.add(btSalir); panel2.add(btTranspuesta); //Formato panel2 panel2.setBackground(green); panel2.setVisible(true); panel2.setBounds(0,0,300,380); //Argregamos componentes al panelPrincipal= panel.add(panel2); //BotonCrear btCrear.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) //throws IOException { if(ventanaAbierta==false) { ventanaAbierta=true; new CrearMatriz(); } else { JOptionPane.showMessageDialog(null,"Ya se crearon las Matrices"); } } }); m3 = new Matriz(ren2,col2); btSumar.addActionListener(new ActionListener() { Matriz m3;//(ren2,col2); public void actionPerformed(ActionEvent e) { m3 = new Matriz(ren2,col2); if(ventanaAbierta==true) { try { crearMat.SUMA(m1,m2); } catch(Exception nul) { System.out.println(nul); } } else { JOptionPane.showMessageDialog(null,"Ya se realizo la suma"); } } }); //BotonSalir btSalir.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { System.exit(0); } }); panel.setVisible(true); panel.setBounds(0,0,350,380); } class VentanaMatriz { private JFrame ventana; private JPanel panel; private JTextArea textArea1,textArea2; private JLabel mat1,mat2; private JTextField textField1; public VentanaMatriz() { panel = new JPanel(); panel.setLayout(null); ventana = new JFrame("Creacion de Matrices"); ventana.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { ventana.dispose(); } }); ventana.setContentPane(panel); ventana.setVisible(true); ventana.setResizable(false); ventana.setBounds(200,100,850,420); } public void inicializarComponentes() { //Colores black = new Color(0,0,0); white = new Color(255,255,255); blue = new Color(0,0,255); green = new Color(0,255,0); red = new Color(255,0,0); //Tipo de letra Verdana14 = new Font("Verdana",Font.BOLD,14); //Tipos de borde borderRed2 = BorderFactory.createLineBorder(red,2); borderBlue2 = BorderFactory.createLineBorder(blue,2); borderGreen2 = BorderFactory.createLineBorder(green,2); borderGreen4 = BorderFactory.createLineBorder(green,4); //Agregando componentes al panel1 panel.add(mat1); panel.add(textArea1); panel.add(mat2); panel.add(textArea2); //Formato panel2 panel.setBackground(blue); panel.setVisible(true); panel.setBounds(0,0,850,420); } } class CrearMatriz { public int col1,re1,ren2,col2; public Matriz m1,m2,m3; public CrearMatriz() { int col1,ren1,ren2,col2; ren2 = Integer.parseInt(JOptionPane.showInputDialog("Numero de Renglones Matriz A: ")); col2 = Integer.parseInt(JOptionPane.showInputDialog("Numero de Columnas Matriz A: ")); final Matriz m1= new Matriz(ren2,col2); ren2 = Integer.parseInt(JOptionPane.showInputDialog("Numero de Renglones Matriz B: ")); col2 = Integer.parseInt(JOptionPane.showInputDialog("Numero de Columnas Matriz B: ")); final Matriz m2= new Matriz(ren2,col2); m3 = new Matriz(ren2,col2); m1.llenarMatriz(); m2.llenarMatriz(); m1.printMat(); m2.printMat(); } public void SUMA(Matriz m1,Matriz m2) { Matriz m3; if(ventanaAbierta==false) { m3 = new Matriz(ren2,col2); if(valida.validaSumayResta(m1,m2)) { m3 = operacion.sumaMat(m1,m2); JOptionPane.showMessageDialog(null,"La suma es = "); m3.imprimeMatriz(); } else { JOptionPane.showMessageDialog(null,"No es posible hacer la suma"); } } } public void RESTA() { } //btSumar = new JButton("Sumar",suma); //BotonSumar //Mostrar matriz 1 y 2 // System.out.println("\n\n\nMatriz 1="); // m1.imprimeMatriz(); // System.out.println("\nMatriz 2="); //Poner en botones /* if(valida.validaSumayResta(m1,m2)) { m3 = operacion.sumaMat(m1,m2); JOptionPane.showMessageDialog(null,"La suma es = "); m3.imprimeMatriz(); } else { JOptionPane.showMessageDialog(null,"No es posible hacer la suma"); } if(valida.validaSumayResta(m1,m2)) { m3=operacion.restaMat(m1,m2); JOptionPane.showMessageDialog(null,"La resta es = "); m3.imprimeMatriz(); } else { JOptionPane.showMessageDialog(null,"No es posible hacer la resta"); } if(valida.validaMultiplicacion(m1,m2)){ m3=operacion.multiplicaMat(m1,m2); JOptionPane.showMessageDialog(null,"La multiplicacion es = "); m3.imprimeMatriz(); } else { JOptionPane.showMessageDialog(null,"No es posible hacer la multiplicacion"); } JOptionPane.showMessageDialog(null,"La multiplicacion es = "); m1=operacion.transpuesta(m1); m2=operacion.transpuesta(m2); */ } class Matriz { public JTextField matriz; //public JTextArea texto; private JFrame ventanaPrintMatriz; private JPanel panel2; int ren; int col; int pos[][]; public Matriz(int ren1, int col1) { ren = ren1; col = col1; pos = new int [ren][col];/*una matriz de enteros de renglon por columan*/ } public void llenarMatriz() { for(int i=0;i<ren;i++) for(int j=0;j<col;j++) pos[i][j]=(int) (Math.random()*10);/*la posicion i y j crea un entero random*/ } /*vuelve a recorrer los espacio de i y j*/ } //Esta clase era un metodo de CrearMatriz class ImprimirMatriz { public void ImprimirMatriz() { panel2 = new JPanel(); panel2.setLayout(null); ventanaPrintMatriz = new JFrame("Matriz"); ventana.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { //Practica2.ventanaAbierta=false; ventana.dispose(); } }); int i,j; int x=0,y=0; borderRed2 = BorderFactory.createLineBorder(red,2); white = new Color(255,255,255); red = new Color(255,0,0); black = new Color(0,0,0); blue = new Color(0,0,255); for(i=0;i<ren;i++) { for(j=0;j<col;j++) { matriz = new JTextField(" "+pos[i][j]); matriz.setBorder(borderRed2); matriz.setForeground(white); matriz.setBounds(x+25,y+25,25,25); matriz.setBackground(black); matriz.setEditable(false); matriz.setVisible(true); //Se incrementa la coordenada en X //para el siguiente Textfield no se encime x=x+35; //Agregamos el textField al panel panel2.add(matriz); } //Regreso las cordenadas de X a 0 para que el //siguiente renglon empieze en donde mismo x=0; //Incremento las coordenada Y para que se brinque //de linea y=y+35; } //Formato panel2 panel2.setBounds(150,150,350,380); panel2.setBackground(blue); //panel2.setEditable(false); panel2.setVisible(true); //Formato de Ventana ventanaPrintMatriz.setContentPane(panel2); ventanaPrintMatriz.setBounds(150,150,350,380); ventanaPrintMatriz.setResizable(false); ventanaPrintMatriz.setVisible(true); } } class Operaciones { public Matriz sumaMat(Matriz m1, Matriz m2) { Matriz m3; m3 = new Matriz(m1.ren, m1.col); for(int i=0;i<m1.col;i++) for(int j=0;j<m1.ren;j++) m3.pos[i][j]=m1.pos[i][j]+m2.pos[i][j]; return m3; } public Matriz restaMat(Matriz m1, Matriz m2) { Matriz m3; m3 = new Matriz(m1.ren, m1.col); for(int i=0;i<m1.col;i++) for(int j=0;j<m1.ren;j++) m3.pos[i][j]=m1.pos[i][j]-m2.pos[i][j]; return m3; } public Matriz multiplicaMat(Matriz m1, Matriz m2) { Matriz m3; m3 = new Matriz(m1.ren, m2.col); for(int i=0;i<m1.ren;i++) for(int j=0;j<m2.col;j++) { m3.pos[i][j]=0; for(int k=0;k<m1.col;k++) m3.pos[i][j]+=(m1.pos[i][k]*m2.pos[k][j]); } return m3; } public Matriz transpuesta(Matriz m1) { Matriz m3=new Matriz(m1.col,m1.ren); for(int i=0;i<m1.col;i++) for(int j=0;j<m1.ren;j++) m3.pos[i][j]=m1.pos[j][i]; return m3; } } class ValidacionesMatrices { public boolean validaSumayResta(Matriz m1, Matriz m2) { if((m1.ren==m2.ren) && (m1.col==m2.col)) return true; else return false; } public boolean validaMultiplicacion(Matriz m1, Matriz m2) { if(((m1.ren==m2.ren) && (m1.col==m2.col)) || (m1.col==m2.ren)) return true; else return false; } } public static void main(String[] args) { Practica2 practica2 = new Practica2(); practica2.inicializarComponentes(); } } Exc

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  • My java program seems to be skipping over the try{}, executing the catch{} and then throwing a NullPointerException. What should I do?

    - by Matt Bolopue
    I am writing a program that calculates the number of words, syllables, and sentences in any given text file. I don't need help finding those numbers, however my program (which currently should only find the number of words in the text file) will not import the text file even when I type in the name of the file correctly. The text file is in the same folder as the source code. Instead it tells me every time that what I typed in has the wrong file extension (see my catch{}) and then proceeds to throw a null pointer. I am at a loss for what could be causing it. Any suggestions? import java.io.*; import java.util.*; public class Reading_Lvl_Calc { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub int words = 0; String fileName; Scanner scan; Scanner keyread = new Scanner(System.in); System.out.println("Please enter a file name (or QUIT to exit)"); fileName = keyread.nextLine(); File doc = new File(fileName); //while(scan.equals(null)){ try { scan = new Scanner(doc); } catch(Exception e) { if(fileName.substring(fileName.indexOf(".")) != ".txt") System.out.println("I'm sorry, the file \"" + fileName + "\" has an invalid file extension."); else System.out.println("I am sorry, the file \"" + fileName + " \" cannot be found.\n The file must be in the same directory as this program"); scan = null; } // } while(scan.hasNext()){ words++; scan.next(); } System.out.println(words); } }

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  • Blogger GData NullPointerException on every second try on Android

    - by Vinay
    I am experiencing a strange phenomenon with Blogger GData API 2.0 on Android. I am using the BloggerService to retrieve blogs. First time it works fine. However EVERY SECOND TRY I get a NullPointerException: Caused by: java.lang.NullPointerException at com.google.gdata.wireformats.AltRegistry.lookupType(AltRegistry.java:190) at com.google.gdata.client.Service.parseResponseData(Service.java:1860) at com.google.gdata.client.Service.getFeed(Service.java:1054) at com.google.gdata.client.Service.getFeed(Service.java:916) at com.google.gdata.client.GoogleService.getFeed(GoogleService.java:631) at com.google.gdata.client.Service.getFeed(Service.java:935)

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