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• How do I create a hyperlink in java?

  - by Justin984

  I'm going through the google app engine tutorials at https://developers.google.com/appengine/docs/java/gettingstarted/usingusers I'm very new to google app engine, java and web programming in general. So my question is, at the bottom of the page it says to add a link to allow the user to log out. So far I've got this: public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException { UserService userService = UserServiceFactory.getUserService(); User user = userService.getCurrentUser(); if(user != null){ resp.setContentType("text/plain"); resp.getWriter().println("Hello, " + user.getNickname()); String logoutLink = String.format("<a href=\"%s\">Click here to log out.</a>", userService.createLogoutURL(req.getRequestURI())); resp.getWriter().println(logoutLink); }else { resp.sendRedirect(userService.createLoginURL(req.getRequestURI())); } } However instead of a link, the full string is printed to the screen including the tags. When I look at the page source, I have no tags or any of the other stuff that goes with a webpage. I guess that makes sense considering I've done nothing to output any of that. Do I just do a bunch of resp.GetWriter().println() statements to output the rest of the webpage, or is there something else I don't know about? Thanks!

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• Multiple HTTP requests using sockets in java

  - by codeomnitrix

  How could i send multiple http requests from my java program using sockets. actually i have tried as: import java.net.*; import java.io.*; class htmlPageFetch{ public static void main(String[] args){ try{ Socket s = new Socket("127.0.0.1", 80); DataInputStream dIn = new DataInputStream(s.getInputStream()); PrintWriter dOut = new PrintWriter(s.getOutputStream(), true); dOut.println("GET /mytesting/justCheck.html HTTP/1.1\r\nHost:localhost\r\n\r\n"); boolean more_data = true; String str; int i = 0; while(more_data){ str = dIn.readLine(); if(str==null){ //Now server has stopped sending data //So now write again the inputs dOut.println("GET /mytesting/justCheck1.html HTTP/1.1\r\nHost:localhost\r\n\r\n"); continue; } System.out.println(str); } }catch(IOException e){ } } } But when I send the request again it was not processed? Thank in advance.

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• Count Occurence of Needle String in Haystack String, most optimally?

  - by Taranfx

  The Problem is simple Find "ABC" in "ABCDSGDABCSAGAABCCCCAAABAABC" Here is the solution I propose, I'm looking for any solutions that might be better than this one. public static void main(String[] args) { String haystack = "ABCDSGDABCSAGAABCCCCAAABAABC"; String needle = "ABC"; char [] needl = needle.toCharArray(); int needleLen = needle.length(); int found=0; char hay[] = haystack.toCharArray(); int index =0; int chMatched =0; for (int i=0; i<hay.length; i++){ if (index >= needleLen || chMatched==0) index=0; System.out.print("\nchar-->"+hay[i] + ", with->"+needl[index]); if(hay[i] == needl[index]){ chMatched++; System.out.println(", matched"); }else { chMatched=0; index=0; if(hay[i] == needl[index]){ chMatched++; System.out.print("\nchar->"+hay[i] + ", with->"+needl[index]); System.out.print(", matched"); }else continue; } if(chMatched == needleLen){ found++; System.out.println("found. Total ->"+found); } index++; } System.out.println("Result Found-->"+found); } It took me a while creating this one. Can someone suggest a better solution (if any) P.S. Drop the sysouts if they look messy to you.

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• How do you get an object associated with a Future Actor?

  - by Bruce Ferguson

  I would like to be able to get access to the object that is being returned from spawning a future import scala.actors.Future import scala.actors.Futures._ class Object1(i:Int) { def getAValue(): Int = {i} } object Test { def main( args: Array[String] ) = { var tests = List[Future[Object1]]() for(i <- 0 until 10) { val test = future { val obj1 = new Object1(i) println("Processing " + i + "...") Thread.sleep(1000) println("Processed " + i) obj1 } tests = tests ::: List(test) } val timeout = 1000 * 60 * 5 // wait up to 5 minutes val futureTests = awaitAll(timeout,tests: _*) futureTests.foreach(test => println("result: " + future())) } } The output from one run of this code is: Processing 0... Processing 1... Processing 2... Processing 3... Processed 0 Processing 4... Processed 1 Processing 5... Processed 2 Processing 6... Processed 3 Processing 7... Processed 4 Processing 8... Processed 6 Processing 9... Processed 5 Processed 7 Processed 8 Processed 9 result: <function0> result: <function0> result: <function0> result: <function0> result: <function0> result: <function0> result: <function0> result: <function0> result: <function0> result: <function0> I've tried future().getClass(), and the output is result: class scala.actors.FutureActor What I'm looking to be able to access is the obj1 objects. Thanks Bruce

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• new Stateful session bean instance without calling lookup

  - by kislo_metal

  Scenario: I have @Singleton UserFactory (@Stateless could be) , its method createSession() generating @Stateful UserSession bean by manual lookup. If I am injecting by DI @EJB - i will get same instance during calling fromFactory() method(as it should be) What I want - is to get new instance of UserSession without preforming lookup. Q1: how could I call new instance of @Stateful session bean? Code: @Singleton @Startup @LocalBean public class UserFactory { @EJB private UserSession session; public UserFactory() { } @Schedule(second = "*/1", minute = "*", hour = "*") public void creatingInstances(){ try { InitialContext ctx = new InitialContext(); UserSession session2 = (UserSession) ctx.lookup("java:global/inferno/lic/UserSession"); System.out.println("in singleton UUID " +session2.getSessionUUID()); } catch (NamingException e) { e.printStackTrace(); } } @Schedule(second = "*/1", minute = "*", hour = "*") public void fromFactory(){ System.out.println("in singleton UUID " +session.getSessionUUID()); } public UserSession creatSession(){ UserSession session2 = null; try { InitialContext ctx = new InitialContext(); session2 = (UserSession) ctx.lookup("java:global/inferno/lic/UserSession"); System.out.println("in singleton UUID " +session2.getSessionUUID()); } catch (NamingException e) { e.printStackTrace(); } return session2; } } As I understand, calling of session.getClass().newInstance(); is not a best idea Q2 : is it true? I am using glassfish v3, ejb 3.1.

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• Java import statement

  - by nattyP

  I am using java on debian 5 java version "1.6.0_20" Java(TM) SE Runtime Environment (build 1.6.0_20-b02) Java HotSpot(TM) Client VM (build 16.3-b01, mixed mode, sharing) Why is there a difference between the following Case 1: import java.util.*; Case 2: import java.util.*; import java.util.Arrays; import java.util.List; Why doesnt the first case cover the second case? The code only compiles when I import Arrays and List explicitly. Code: import java.util.*; import java.util.Arrays; import java.util.List; public class Test { public static void main (String[] args) { List<Integer> i = new ArrayList(Arrays.asList(1,2,3,4,5,6,7,8,9,10)); List<Integer> j = new ArrayList(); ListIterator<Integer> n = i.listIterator(i.size()); while(n.hasPrevious()) { j.add(n.previous()); } println(j); } static void println(Object o) { System.out.println(o); } static void print(Object o) { System.out.print(o); } }

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• Looking for Go equivalent of scanf.

  - by Stephen Hsu

  I'm looking for the Go equivalent of scanf(). I tried with following code: 1 package main 2 3 import ( 4 "scanner" 5 "os" 6 "fmt" 7 ) 8 9 func main() { 10 var s scanner.Scanner 11 s.Init(os.Stdin) 12 s.Mode = scanner.ScanInts 13 tok := s.Scan() 14 for tok != scanner.EOF { 15 fmt.Printf("%d ", tok) 16 tok = s.Scan() 17 } 18 fmt.Println() 19 } I run it with input from a text with a line of integers. But it always output -3 -3 ... And how to scan a line composed of a string and some integers? Changing the mode whenever encounter a new data type? The Package documentation: Package scanner A general-purpose scanner for UTF-8 encoded text. But it seems that the scanner is not for general use. Updated code: func main() { n := scanf() fmt.Println(n) fmt.Println(len(n)) } func scanf() []int { nums := new(vector.IntVector) reader := bufio.NewReader(os.Stdin) str, err := reader.ReadString('\n') for err != os.EOF { fields := strings.Fields(str) for _, f := range fields { i, _ := strconv.Atoi(f) nums.Push(i) } str, err = reader.ReadString('\n') } r := make([]int, nums.Len()) for i := 0; i < nums.Len(); i++ { r[i] = nums.At(i) } return r }

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• Line End Problem Reading with Scanner Class in Java

  - by dikbas

  I am not an experienced Java programmer and i'm trying to write some text to a file and then read it with Scanner. I know there are lots of ways of doing this, but i want to write records to file with delimiters, then read the pieces. The problem is so small. When I look the output some printing isn't seen(shown in below). I mean the bold line in the Output that is only written "Scanner". I would be appreciated if anyone can answer why "String: " isn't seen there. (Please answer just what i ask) I couldn't understand if it is a simple printing problem or a line end problem with "\r\n". Here is the code and output: import java.io.FileReader; import java.io.FileWriter; import java.io.IOException; import java.util.Scanner; public class Tmp { public static void main(String args[]) throws IOException { int i; boolean b; String str; FileWriter fout = new FileWriter("test.txt"); fout.write("Testing|10|true|two|false\r\n"); fout.write("Scanner|12|one|true|"); fout.close(); FileReader fin = new FileReader("Test.txt"); Scanner src = new Scanner(fin).useDelimiter("[|\\*]"); while (src.hasNext()) { if (src.hasNextInt()) { i = src.nextInt(); System.out.println("int: " + i); } else if (src.hasNextBoolean()) { b = src.nextBoolean(); System.out.println("boolean: " + b); } else { str = src.next(); System.out.println("String: " + str); } } fin.close(); } } Here is the output: String: Testing int: 10 boolean: true String: two String: false Scanner int: 12 String: one boolean: true

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• Java: Copying an exe-file and launching afterwards fails

  - by Philip

  Hi, I want to copy an existing .exe-file from one directory to another and launch it afterwards with Java. Like this: FileIO.copy( new File( sourceFile ), new File( targetFile ) ); System.out.println( "Existing: " + new File( targetFile ).exists() ); System.out.println( "Launching " + targetFile ); String cmd[] = { targetFile }; Process p = Runtime.getRuntime().exec( cmd ); p.waitFor(); System.out.println( "Result: " + p.exitValue() ); The output is like this: Existing: true Launching C:\test\Launcher.new.exe Result: 2 So Java says that the file is valid and existing, but Windows just can't launch the process because it thinks the file is not there. The pathes are absolute and with backslashes. I also have all permissions on the files so I'm allowed to execute them. The Launcher.new.exe is generated by Launch4j, so it's more or less standalone. At least it doesn't depend on DLLs in the same folder. But strange: It works when I copy and launch the notepad.exe. One more strange thing: If I don't copy the file by Java but by hand, the launching also fails with the same error. OS is Vista with SP1. Any clue?

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• Java Applet 411 Content Length

  - by user1903006

  I am new to Java. I wrote an applet with a gui that sends results (int w and int p) to a server, and I get the "411 Length Required" error. What am I doing wrong? How do you set a Content-Length? This is the method that communicates with the server: public void sendPoints1(int w, int p){ try { String url = "http://somename.com:309/api/Results"; String charset = "UTF-8"; String query = String.format("?key=%s&value=%s", URLEncoder.encode(String.valueOf(w), charset), URLEncoder.encode(String.valueOf(p), charset)); String length = String.valueOf((url + query).getBytes("UTF-8").length); HttpURLConnection connection = (HttpURLConnection) new URL(url + query).openConnection(); connection.setRequestMethod("POST"); connection.setRequestProperty("Content-Length", length); connection.connect(); System.out.println("Responce Code: " + connection.getResponseCode()); System.out.println("Responce Message: " + connection.getResponseMessage()); } catch (Exception e) { System.err.println(e.getMessage()); } }

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• implement AOP for Controllers in Spring 3

  - by tommy

  How do I implement AOP with an annotated Controller? I've search and found two previous posts regarding the problem, but can't seem to get the solutions to work. posted solution 1 posted solution 2 Here's what I have: Dispatch Servlet: <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:aop="http://www.springframework.org/schema/aop" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd"> <context:annotation-config/> <context:component-scan base-package="com.foo.controller"/> <bean id="fooAspect" class="com.foo.aop.FooAspect" /> <aop:aspectj-autoproxy> <aop:include name="fooAspect" /> </aop:aspectj-autoproxy> </beans> Controller: @Controller public class FooController { @RequestMapping(value="/index.htm", method=RequestMethod.GET) public String showIndex(Model model){ return "index"; } } Aspect: @Aspect public class FooAspect { @Pointcut("@target(org.springframework.stereotype.Controller)") public void controllerPointcutter() {} @Pointcut("execution(* *(..))") public void methodPointcutter() {} @Before("controllerPointcutter()") public void beforeMethodInController(JoinPoint jp){ System.out.println("### before controller call..."); } @AfterReturning("controllerPointcutter() && methodPointcutter() ") public void afterMethodInController(JoinPoin jp) { System.out.println("### after returning..."); } @Before("methodPointcutter()") public void beforeAnyMethod(JoinPoint jp){ System.out.println("### before any call..."); } } The beforeAnyMethod() works for methods NOT in a controller; I cannot get anything to execute on calls to controllers. Am I missing something?

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• Swing modal dialog refuses to close - sometimes!

  - by Zarkonnen

  // This is supposed to show a modal dialog and then hide it again. In practice, // this works about 75% of the time, and the other 25% of the time, the dialog // stays visible. // This is on Ubuntu 10.10, running: // OpenJDK Runtime Environment (IcedTea6 1.9) (6b20-1.9-0ubuntu1) // This always prints // setVisible(true) about to happen // setVisible(false) about to happen // setVisible(false) has just happened // even when the dialog stays visible. package modalproblemdemo; import java.awt.Frame; import javax.swing.JDialog; import javax.swing.SwingUtilities; public class Main { public static void main(String[] args) { final Dialogs d = new Dialogs(); new Thread() { @Override public void run() { d.show(); d.hide(); } }.start(); } static class Dialogs { final JDialog dialog; public Dialogs() { dialog = new JDialog((Frame) null, "Hello World", /*modal*/ true); dialog.setSize(400, 200); } public void show() { SwingUtilities.invokeLater(new Runnable() { public void run() { dialog.setLocationRelativeTo(null); System.out.println("setVisible(true) about to happen"); dialog.setVisible(true); }}); } public void hide() { SwingUtilities.invokeLater(new Runnable() { public void run() { System.out.println("setVisible(false) about to happen"); dialog.setVisible(false); System.out.println("setVisible(false) has just happened"); }}); } } }

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• java: how to parse html-like xml

  - by Yang

  I have an html-like xml, basically it is html. I need to get the elements in each . Each element looks like this: <line tid="744476117"> <attr>1414</attr> <attr>31</attr><attr class="thread_title">title1</attr><attr>author1</attr><attr>date1</attr></line> My code is as below, it does recognize that there are 50 in the file, but it gives me NULLPointException when parsing NodeList fstNmElmntLst = fstElmnt.getElementsByTagName("attr"); Any idea why this is happening? The same code has been used for other applications without problems. DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); DocumentBuilder db = dbf.newDocumentBuilder(); InputSource is = new InputSource(); is.setCharacterStream(new StringReader(cleanxml)); Document doc = db.parse(is); doc.getDocumentElement().normalize(); System.out.println("Root element " + doc.getDocumentElement().getNodeName()); NodeList nodeLst = doc.getElementsByTagName("line"); for (int s = 0; s < nodeLst.getLength(); s++) { System.out.println(nodeLst.getLength()); Node fstNode = nodeLst.item(s); if (fstNode.getNodeType() == Node.ELEMENT_NODE) { Element fstElmnt = (Element) fstNode; NodeList fstNmElmntLst = fstElmnt.getElementsByTagName("attr"); Element fstNmElmnt = (Element) fstNmElmntLst.item(0); NodeList fstNm = fstNmElmnt.getChildNodes(); System.out.println("attr : " + ((Node) fstNm.item(0)).getNodeValue()); } }

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• Append data to same text file

  - by Manu

  SimpleDateFormat formatter = new SimpleDateFormat("ddMMyyyy_HHmmSS"); String strCurrDate = formatter.format(new java.util.Date()); String strfileNm = "Customer_" + strCurrDate + ".txt"; String strFileGenLoc = strFileLocation + "/" + strfileNm; String Query1="select '0'||to_char(sysdate,'YYYYMMDD')||'123456789' class_code from dual"; String Query2="select '0'||to_char(sysdate,'YYYYMMDD')||'123456789' class_code from dual"; try { Statement stmt = null; ResultSet rs = null; Statement stmt1 = null; ResultSet rs1 = null; stmt = conn.createStatement(); stmt1 = conn.createStatement(); rs = stmt.executeQuery(Query1); rs1 = stmt1.executeQuery(Query2); File f = new File(strFileGenLoc); OutputStream os = (OutputStream)new FileOutputStream(f,true); String encoding = "UTF8"; OutputStreamWriter osw = new OutputStreamWriter(os, encoding); BufferedWriter bw = new BufferedWriter(osw); while (rs.next() ) { bw.write(rs.getString(1)==null? "":rs.getString(1)); bw.write(" "); } bw.flush(); bw.close(); } catch (Exception e) { System.out.println( "Exception occured while getting resultset by the query"); e.printStackTrace(); } finally { try { if (conn != null) { System.out.println("Closing the connection" + conn); conn.close(); } } catch (SQLException e) { System.out.println( "Exception occured while closing the connection"); e.printStackTrace(); } } return objArrayListValue; } The above code is working fine. it writes the content of "rs" resultset data in text file Now what i want is ,i need to append the the content in "rs2" resultset to the "same text file"(ie . i need to append "rs2" content with "rs" content in the same text file)..

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• java oracle syntax error?

  - by murali

  hi, i am using the following code for the uploading keywords & count to the excel file. i am having the keyword_id as primary key for that one i had written sentence...i am having the twocolumns in the excel file..1.keyword 2.count my code is: while (rs.next()) { System.out.println("inside "); String keyword = rs.getString(1); int count = rs.getInt(2); System.out.println("insert into SEARCHABLE_KEYWORDS values ('"+ keyword+"','"+count+"')"); stmtdb.execute("insert into SEARCHABLE_KEYWORDS (keyword_id,keyword,count) values ('"+ "select Searchable_Keywords_sequence.nextval from dual"+ "','"+keyword+"','"+count+"')"); System.out.println(keyword + " " + keyword+" count "+count); } but I am getting the following error: java.sql.SQLException: [Microsoft][ODBC Excel Driver] Too few parameters. Expected 1. at sun.jdbc.odbc.JdbcOdbc.createSQLException(JdbcOdbc.java:6998) at sun.jdbc.odbc.JdbcOdbc.standardError(JdbcOdbc.java:7155) at sun.jdbc.odbc.JdbcOdbc.SQLExecDirect(JdbcOdbc.java:3151) at sun.jdbc.odbc.JdbcOdbcStatement.execute(JdbcOdbcStatement.java:378) at sun.jdbc.odbc.JdbcOdbcStatement.executeQuery(JdbcOdbcStatement.java:284) at keywordsreader.main(keywordsreader.java:42) please help to slove this problem...

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• Trouble accessing fields of a serialized object in Java

  - by typoknig

  I have instantized a class that implements Serializable and I am trying to stream that object like this: try{ Socket socket = new Socket("localhost", 8000); ObjectOutputStream toServer = new ObjectOutputStream(socket.getOutputStream()); toServer.writeObject(myObject); } catch (IOException ex) { System.err.println(ex); } All good so far right? Then I am trying to read the fields of that object like this: //This is an inner class class HandleClient implements Runnable{ private ObjectInputStream fromClient; private Socket socket; // This socket was established earlier try { fromClient = new ObjectInputStream(socket.getInputStream()); GetField inputObjectFields = fromClient.readFields(); double myFristVariable = inputObjectFields.get("myFirstVariable", 0); int mySecondVariable = inputObjectFields.get("mySecondVariable", 0); //do stuff } catch (IOException ex) { System.err.println(ex); } catch (ClassNotFoundException ex) { System.err.println(ex); } finally { try { fromClient.close(); } catch (Exception ex) { ex.printStackTrace(); } } } But I always get the error: java.io.NotActiveException: not in call to readObject This is my first time streaming objects instead of primitive data types, what am I doing wrong? BONUS When I do get this working correctly, is the ENTIRE CLASS passed with the serialized object (i.e. will I have access to the methods of the object's class)? My reading suggests that the entire class is passed with the object, but I have been unable to use the objects methods thus far. How exactly do I call on the object's methods? In addition to my code above I also experimented with the readObject method, but I was probably using it wrong too because I couldn't get it to work. Please enlighten me.

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• Set the amount of rows JList show (Java)

  - by Alex Cheng

  Hi all. Problem: I have a method that creates a list from the parsed ArrayList. I manage to show the list in the GUI, without scrollbar. However, I am having problem setting it to show only the size of ArrayList. Meaning, say if the size is 6, there should only be 6 rows in the shown List. Below is the code that I am using. I tried setting the visibleRowCount as below but it does not work. I tried printing out the result and it shows that the change is made. private void createSuggestionList(ArrayList<String> str) { int visibleRowCount = str.size(); System.out.println("visibleRowCount " + visibleRowCount); listForSuggestion = new JList(str.toArray()); listForSuggestion.setSelectionMode(ListSelectionModel.SINGLE_SELECTION); listForSuggestion.setSelectedIndex(0); listForSuggestion.setVisibleRowCount(visibleRowCount); System.out.println(listForSuggestion.getVisibleRowCount()); listScrollPane = new JScrollPane(listForSuggestion); MouseListener mouseListener = new MouseAdapter() { @Override public void mouseClicked(MouseEvent mouseEvent) { JList theList = (JList) mouseEvent.getSource(); if (mouseEvent.getClickCount() == 2) { int index = theList.locationToIndex(mouseEvent.getPoint()); if (index >= 0) { Object o = theList.getModel().getElementAt(index); System.out.println("Double-clicked on: " + o.toString()); } } } }; listForSuggestion.addMouseListener(mouseListener); textPane.add(listScrollPane); repaint(); } To summarize: I want the JList to show as many rows as the size of the parsed ArrayList, without a scrollbar. Any ideas? Please help. Thanks. Please let me know if a picture of the problem is needed in case I did not phrase my question correctly.

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• facing issue when using JDBC in TomCat 7 with Struts

  - by Chethu2288

  Am developing a web application using Struts 2 where am trying to insert some values into my local MySql database. The code for connecting and accessing database works fine in console application. but its giving "java.lang.ClassNotFoundException: com.mysql.jdbc.Driver" exception when i tried the same code in Struts. Kindly help me on this. Connection conn = null; String url = "jdbc:mysql://localhost:3306/"; String dbName = "testdatabase"; String driver = "com.mysql.jdbc.Driver"; try { Class.forName(driver).newInstance(); conn = DriverManager.getConnection(url+dbName,"root","root"); Statement statement=conn.createStatement(); System.out.println("HelloWorld.execute()"); int i= statement.executeUpdate("INSERT INTO testTable VALUES('15','Lucky')"); System.out.println("res: "+i); } catch(Exception e) { System.out.println(e); //setMessage(e.getMessage()); } Awaiting your response.

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• Java: Inputting text from a file using split

  - by 00PS

  I am inputting an adjacency list for a graph. There are three columns of data (vertex, destination, edge) separated by a single space. Here is my implementation so far: FileStream in = new FileStream("input1.txt"); Scanner s = new Scanner(in); String buffer; String [] line = null; while (s.hasNext()) { buffer = s.nextLine(); line = buffer.split("\\s+"); g.add(line[0]); System.out.println("Added vertex " + line[0] + "."); g.addEdge(line[0], line[1], Integer.parseInt(line[2])); System.out.println("Added edge from " + line[0] + " to " + line[1] + " with a weight of " + Integer.parseInt(line[2]) + "."); } System.out.println("Size of graph = " + g.size()); Here is the output: Added vertex a. Added edge from a to b with a weight of 9. Exception in thread "main" java.lang.NullPointerException at structure5.GraphListDirected.addEdge(GraphListDirected.java:93) at Driver.main(Driver.java:28) I was under the impression that line = buffer.split("\\s+"); would return a 2 dimensional array of Strings to the variable line. It seemed to work the first time but not the second. Any thoughts? I would also like some feedback on my implementation of this problem. Is there a better way? Anything to help out a novice! :)

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• Getting Junk characters while trying to print the file contents using Java

  - by user1523797

  I am reading a file's contents and trying to print the contents using java. But it prints junk characters along with the file content. Code: import java.io.*; public class ReadFile { public String readFile(String filePath){ StringBuilder contents = new StringBuilder(); File file = new File(filePath); try{ String lines = null; FileReader fileReader1 = new FileReader(file); BufferedReader buffer = new BufferedReader(fileReader1); while((lines = buffer.readLine())!=null){ contents.append(lines); } buffer.close(); } catch(FileNotFoundException ex){ System.out.println("File not found."); }catch(IOException ex){ System.out.println("Exception ocurred."); } return contents.toString(); } public static void main(String[] args){ ReadFile rf = new ReadFile(); String lines = rf.readFile("C:\\Data\\FaultDn.txt"); System.out.println("Original file contents: " + lines); } } The file contents are: partner.cisco.com:org-root/mac-pool-QA_MAC_Pool_5-Sep-2012_12:00 The output is:  Can you please point me to what I am missing in this code?

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• post increment operator java

  - by srandpersonia

  I can't make heads or tails of the following code from "java puzzlers" by joshua bloch. public class Test22{ public static void main(String args[]){ int j=0; for(int i=0;i<100;i++){ j=j++; } System.out.println(j); //prints 0 int a=0,b=0; a=b++; System.out.println(a); System.out.println(b); //prints 1 } } I can't get the part where j prints 0. According to the author, j=j++ is similar to temp=j; j=j+1; j=temp; But a=b++ makes b 1. So it should've evaluated like this, a=b b=b+1 By following the same logic, shouldn't j=j++ be evaluated as, j=j j=j+1 Where does the temp come into picture here? Any explanations would be much appreciated. << I'm breaking my head over this. ;) Thanks in advance.

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• How to show alert in a jsp from a servlet and then redirect to another jsp?

  - by Xaul Omar Tobar

  I tried this but does not display the message only redirects login.jsp <form method="post" action="Login_Servlet" > <input name="idUsuario" type="text"/> <input name="password" type="password" /> <button type="submit">Entrar</button> </form> Login_Servlet response.setContentType("text/html;charset=UTF-8"); PrintWriter out = response.getWriter(); String userid= request.getParameter("idUser"); String password = request.getParameter("password"); Login_Service login_Service = new Login_Service(); boolean result = login_Servicio.aut(userid, password); Usuario user = login_Servicio.getUsuariosByUsuario(userid); if(result == true){ request.getSession().setAttribute("user", user); response.sendRedirect("vistas/Inicio.jsp"); } else{ out.println("<script type=\"text/javascript\">"); out.println("alert('User or password incorrect');"); out.println("</script>"); response.sendRedirect("index.jsp"); } Is it possible to display a message like this? if so I'm doing wrong?

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• Getting information from servlet created html

  - by user541597

  I have a servlet that creates an html text box and then redirects to another servlet on submit. How can I access the value of the html text box from the new servlet? I am able to access servlet variables from the new servlet but I am not aware of how to access the value of the html generated code. thanks, Here is the servlet that gets the text input public class ServletB extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { response.setContentType("text/html"); String value = System.getProperty("card"); PrintWriter out = response.getWriter(); out.println("<center><h1>Your preffered method of payment is "+value+"</h1><br />"); out.println("Please Enter Card Number<input type =\"text\" name = \"number\"/><form action=\"http://codd.cs.gsu.edu:9999/cpereyra183/servlet/ServletC\"><input type =\"submit\" value=\"Continue\" /><input type=\"button\" value=\"Cancel\" /></center>"); } }} This is the servlet the first servlet redirects to all I do is try to do is output the text input public class ServletC extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { response.setContentType("text/html"); String value = System.getProperty("card"); PrintWriter out = response.getWriter(); out.println(request.getParameter("number")); } }

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• Best way to run multiple queries per second on database, performance wise?

  - by Michael Joell

  I am currently using Java to insert and update data multiple times per second. Never having used databases with Java, I am not sure what is required, and how to get the best performance. I currently have a method for each type of query I need to do (for example, update a row in a database). I also have a method to create the database connection. Below is my simplified code. public static void addOneForUserInChannel(String channel, String username) throws SQLException { Connection dbConnection = null; PreparedStatement ps = null; String updateSQL = "UPDATE " + channel + "_count SET messages = messages + 1 WHERE username = ?"; try { dbConnection = getDBConnection(); ps = dbConnection.prepareStatement(updateSQL); ps.setString(1, username); ps.executeUpdate(); } catch(SQLException e) { System.out.println(e.getMessage()); } finally { if(ps != null) { ps.close(); } if(dbConnection != null) { dbConnection.close(); } } } And my DB connection private static Connection getDBConnection() { Connection dbConnection = null; try { Class.forName(DB_DRIVER); } catch (ClassNotFoundException e) { System.out.println(e.getMessage()); } try { dbConnection = DriverManager.getConnection(DB_CONNECTION, DB_USER,DB_PASSWORD); return dbConnection; } catch (SQLException e) { System.out.println(e.getMessage()); } return dbConnection; } This seems to be working fine for now, with about 1-2 queries per second, but I am worried that once I expand and it is running many more, I might have some issues. My questions: Is there a way to have a persistent database connection throughout the entire run time of the process? If so, should I do this? Are there any other optimizations that I should do to help with performance? Thanks

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• Downloading Large JSON File to local file using Java

  - by user1279675

  I'm attempting to download a JSON from the following URL - http://api.crunchbase.com/v/1/companies.js - to a local file. I'm using Java 1.7 and the following JSON Libraries - http://www.json.org/java/ - to attempt to make it work. Here's my code: public static void download(String address, String localFileName) { OutputStream out = null; URLConnection conn = null; InputStream in = null; try { URL url = new URL(address); out = new BufferedOutputStream( new FileOutputStream(localFileName)); conn = url.openConnection(); in = conn.getInputStream(); byte[] buffer = new byte[1024]; int numRead; long numWritten = 0; while ((numRead = in.read(buffer)) != -1) { out.write(buffer, 0, numRead); numWritten += numRead; System.out.println(buffer.length); System.out.println(" " + buffer.hashCode()); } System.out.println(localFileName + "\t" + numWritten); } catch (Exception exception) { exception.printStackTrace(); } finally { try { if (in != null) { in.close(); } if (out != null) { out.close(); } } catch (IOException ioe) { } } } When I run the code everything seems to work until midway through the loop the program seems to stop and not continue reading the JSON Object. Does anyone know why this would stop reading? How could I fix the issue?

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