Search Results

Search found 33297 results on 1332 pages for 'java java ee'.

Page 313/1332 | < Previous Page | 309 310 311 312 313 314 315 316 317 318 319 320  | Next Page >

  • How are ambigous methods resolved in java ?

    - by Jijoy
    Hi, I have a question. package org.study.algos; public class Study { public static void main(String[] args) { A a = new A(); a.m1(null); } } class A { public void m1(String s) { System.out.println("String"); System.out.println(s); } public void m1(Object obj) { System.out.println("Object"); System.out.println(obj); } } Here, the output is String null Why does the JVM resolve the method to one with a String argument? Thanks in advance J

    Read the article

  • Relating text fields to check boxes in Java

    - by Finzz
    This program requires the user to login and request a database to access. The program then gets a connection object, searches through the database storing the column names into a vector for later use. The problem comes with implementing text fields to allow the user to search for specific values within the database. I can get the check boxes and text fields to appear using a gridlayout and add them to a panel. How do I relate the text fields to their appropriate check box? I've tried adding them to a vector, but then they can't also be added to the panel as well. I've searched for a way to name the text fields as the loop cycles through the column names, but it seems impossible to do without having them declared ahead of time. This can't be done either, as it's impossible to determine the attributes that the user will request. I just need to be able to know the names of the text fields so I can test to see if the user entered information and perform the necessary logic. Let me know if you have to see the rest of the code to give an answer, but hopefully you get the general idea of what I'm trying to accomplish. Picture of UI: try { ResultSet r2 = con.getMetaData().getColumns("", "", rb.getText(), ""); colNames1 = new Vector<String>(); columns1 = new Vector<JCheckBox>(); while (r2.next()) { colNames1.add(r2.getString(4)); JCheckBox cb = new JCheckBox(r2.getString(4)); JTextField tf = new JTextField(10); columns1.add(cb); p3.add(cb); p3.add(tf); } }

    Read the article

  • Java's Swing Threading

    - by nevets1219
    My understanding is that if I start up another thread to perform some actions, I would need to SwingUtilities.invokeAndWait or SwingUtilities.invokeLater to update the GUI while I'm in said thread. Please correct me if I'm wrong. What I'm trying to accomplish is relatively straightforward: when the user clicks submit, I want to (before performing any actions) disable the submit button, perform the action, and at the end of the action re-enable the button. My method to perform the action updates the GUI directly (displays results) when it gets the results back. This action basically queries a server and gets some results back. What I have so far is: boolean isRunning = false; synchronized handleButtonClick() { if ( isRunning == false ) { button.setEnabled( false ); isRunning = true; doAction(); } } doAction() { new Thread() { try { doAction(); // Concern A } catch ( ... ) { displayStackTrace( ... ); // Concern B } finally { SwingUtilities.invokeLater ( /* simple Runnable to enable button */ ); isRunning = false; } } } For both of my concerns above, do I would have to use SwingUtilities.invokeAndWait since they both will update the GUI? All GUI updates revolve around updating JTextPane. Do I need to in my thread check if I'm on EDT and if so I can call my code (regardless of whether it updates the GUI or not) and NOT use SwingUtilities.invokeAndWait?

    Read the article

  • java: assigning object reference IDs for custom serialization

    - by Jason S
    For various reasons I have a custom serialization where I am dumping some fairly simple objects to a data file. There are maybe 5-10 classes, and the object graphs that result are acyclic and pretty simple (each serialized object has 1 or 2 references to another that are serialized). For example: class Foo { final private long id; public Foo(long id, /* other stuff */) { ... } } class Bar { final private long id; final private Foo foo; public Bar(long id, Foo foo, /* other stuff */) { ... } } class Baz { final private long id; final private List<Bar> barList; public Baz(long id, List<Bar> barList, /* other stuff */) { ... } } The id field is just for the serialization, so that when I am serializing to a file, I can write objects by keeping a record of which IDs have been serialized so far, then for each object checking whether its child objects have been serialized and writing the ones that haven't, finally writing the object itself by writing its data fields and the IDs corresponding to its child objects. What's puzzling me is how to assign id's. I thought about it, and it seems like there are three cases for assigning an ID: dynamically-created objects -- id is assigned from a counter that increments reading objects from disk -- id is assigned from the number stored in the disk file singleton objects -- object is created prior to any dynamically-created object, to represent a singleton object that is always present. How can I handle these properly? I feel like I'm reinventing the wheel and there must be a well-established technique for handling all the cases.

    Read the article

  • Download Large Files using java

    - by angelina
    Dear All, I M building a application in which i want to download large files on handset (mobile),but if size of file is large i m getting exception socket exception-broken pipe . inputStream = new FileInputStream(path); byte[] buffer = new byte[1024]; int bytesRead = 0; do { bytesRead = inputStream.read(buffer, offset, buffer.length); resp.getOutputStream().write(buffer, 0, bytesRead); } while (bytesRead == buffer.length); resp.getOutputStream().flush(); }

    Read the article

  • java /TableModel of Objects/Update Object"

    - by Tomás Ó Briain
    I've a collection of Stock objects that I'm updating about 10/15 variables for in real-time. I'm accessing each Stock by its ID in the collection. I'm also trying to display this in a JTable and have implemented an AbstractTablemodel. It's not working too well. I've a RowMap that I add each ID to as Stocks are added to the TableModel. To update the prices and variables of all the stocks in the TableModel, I want to send a Stock object to an updateModel(Stock s) method. I can find the relevant row by searching the map, but how do I handle this nicely, so I don't have to start iterating through table columns and comparing the values of the cells to the variables of the object to see whether there are any differences?? Basically, i want to send a Stock object to the TableModel and update cells if there are changes and do nothing if there aren't. Any ideas about how to implement a TableModel that might do this? Any pointeres at all would be appreciated. Thanks.

    Read the article

  • Java Split not working as expected

    - by daaabears
    I am trying to use a simple split to break up the following string: 00-00000 My expression is: ^([0-9][0-9])(-)([0-9])([0-9])([0-9])([0-9])([0-9]) And my usage is: String s = "00-00000"; String pattern = "^([0-9][0-9])(-)([0-9])([0-9])([0-9])([0-9])([0-9])"; String[] parts = s.split(pattern); If I play around with the Pattern and Matcher classes I can see that my pattern does match and the matcher tells me my groupCount is 7 which is correct. But when I try and split them I have no luck.

    Read the article

  • java objects, shared variables

    - by raven
    hello, I have a simple question here. If I declare a variable inside an object which was made [declared] in the main class, like this: public static int number; ( usually I declare it like this : private int number; ) can it be used in a different object which was also made [declared] in the main class? btw I do not care about security atm, I just want to make something work, don't care about protection)

    Read the article

  • java Swing Listeners: components listening at each others.

    - by Pierre
    Hi all, I want to code two JList (categories and items). When I click one category it should select all the items for that category and when I click on one item it should select its categories. So both JList will have a ListSelectionListener listening at each other and changing the selection. Should I fear about some a of "loop" ? Is there a way to tell that an Event has been consumed ? how do people manage that kind of situation ? Thanks

    Read the article

  • Simple Question:Output of below Java program

    - by Abhishek Jain
    public class abc1 { private String s; public abc1(String s){this.s=s;} public static void main(String args[]) { HashSet<Object> hs=new HashSet<Object>(); abc1 a1= new abc1("abc"); abc1 a2= new abc1("abc"); String s1= new String("abc"); String s2= new String("abc"); hs.add(a1); hs.add(a2); hs.add(s1); hs.add(s2); System.out.println(hs.size()); } } Why above program output is 3?

    Read the article

  • Java: stopping long HTTP operations

    - by kilonet
    I'm using Apache Common library for HTTP operations: HttpClient client = getClient(); PutMethod put = new PutMethod(url); FileRequestEntity countingFileRequestEntity = new FileRequestEntity(file, "application/octet-stream"); put.setRequestEntity(countingFileRequestEntity); client.executeMethod(put); put.releaseConnection(); I wonder how can safely interrup long HTTP operation. Running it in new thread and stopping it seems to be wrong way. HttpMethodBase has abort() method, but I can't understand how to use it because client.executeMethod blocks execution until it complets

    Read the article

  • Need to split a string into two parts in java

    - by Reddy
    I have a string which contains a contiguous chunk of digits and then a contiguous chunk of characters. I need to split them into two parts (one integer part, and one string). I tried using String.split("\D", 1), but it is eating up first character. I checked all the String API and didn't find a suitable method. Is there any method for doing this thing?

    Read the article

  • Question About Eclipse Java Debugger Conditional Breakpoints Inefficiency

    - by Personman
    I just set a conditional breakpoint in Eclipse's debugger with a mildly inefficient condition by breakpoint standards - checking whether a HashMap's value list (8 elements) contains Double.NaN. This resulted in an extremely noticeable slowdown in performance - after about five minutes, I gave up. Then I copy pasted the condition into an if statement at the exact same line, put a noop in the if, and set a normal breakpoint there. That breakpoint was reached in the expected 20-30 seconds. Is there something special that conditional breakpoints do that is different from this, or is Eclipse's implementation just kinda stupid? It seems like they could fairly easily just do exactly the same thing behind the scenes.

    Read the article

  • Extract two double Values from String using RegEx in Java

    - by tzippy
    I am reading a file by line and need to extract latitude and longitude from it. This how lines can looks: DE 83543 Rott am Inn Bayern BY Oberbayern Landkreis Rosenheim 47.983 12.1278 DE 21147 Hamburg Hamburg HH Kreisfreie Stadt Hamburg 53.55 10 What's for sure is, there are no dots surrounded by digits except for the ones representing the doubles. Unfortunately there are Values without a dot, so it's probably best to check for numbers from the end of the String. thanks for your help!

    Read the article

  • java.lang.NumberFormatException: unable to parse '' as integer one more time

    - by Quzziy
    I will take two numbers from user, but this number from EditText must be converted to int. I think it should be working, but I still have problem with compilation code in Android Studio. CatLog show error in line with: int wiek = Integer.parseInt(wiekEditText.getText().toString()); Below is my full Android code: public class MyActivity extends ActionBarActivity { int Wynik; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_my); int Tmax, RT; EditText wiekEditText = (EditText) findViewById(R.id.inWiek); EditText tspoczEditText = (EditText) findViewById(R.id.inTspocz); int wiek = Integer.parseInt(wiekEditText.getText().toString()); int tspocz = Integer.parseInt(tspoczEditText.getText().toString()); Tmax = 220 - wiek; RT = Tmax - tspocz; Wynik = 70*RT/100 + tspocz; final EditText tempWiekEdit = wiekEditText; TabHost tabHost = (TabHost) findViewById(R.id.tabHost); //Do TabHost'a z layoutu tabHost.setup(); TabHost.TabSpec tabSpec = tabHost.newTabSpec("Calc"); tabSpec.setContent(R.id.Calc); tabSpec.setIndicator("Calc"); tabHost.addTab(tabSpec); tabSpec = tabHost.newTabSpec("Hints"); tabSpec.setContent(R.id.Hints); tabSpec.setIndicator("Hints"); tabHost.addTab(tabSpec); final Button Btn = (Button) findViewById(R.id.Btn); Btn.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Toast.makeText(getApplicationContext(),"blablabla"+ "Wynik",Toast.LENGTH_SHORT).show(); } }); wiekEditText.addTextChangedListener(new TextWatcher() { @Override public void beforeTextChanged(CharSequence s, int start, int count, int after) { } @Override public void onTextChanged(CharSequence s, int start, int before, int count) { Btn.setEnabled(!(tempWiekEdit.getText().toString().trim().isEmpty())); } @Override public void afterTextChanged(Editable s) { } }); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.my, menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { // Handle action bar item clicks here. The action bar will // automatically handle clicks on the Home/Up button, so long // as you specify a parent activity in AndroidManifest.xml. int id = item.getItemId(); if (id == R.id.action_settings) { return true; } return super.onOptionsItemSelected(item); } }

    Read the article

  • Java Flow Control Problem

    - by Kyle_Solo
    I am programming a simple 2d game engine. I've decided how I'd like the engine to function: it will be composed of objects containing "events" that my main game loop will trigger when appropriate. A little more about the structure: Every GameObject has an updateEvent method. objectList is a list of all the objects that will receive update events. Only objects on this list have their updateEvent method called by the game loop. I’m trying to implement this method in the GameObject class (This specification is what I’d like the method to achieve): /** * This method removes a GameObject from objectList. The GameObject * should immediately stop executing code, that is, absolutely no more * code inside update events will be executed for the removed game object. * If necessary, control should transfer to the game loop. * @param go The GameObject to be removed */ public void remove(GameObject go) So if an object tries to remove itself inside of an update event, control should transfer back to the game engine: public void updateEvent() { //object's update event remove(this); System.out.println("Should never reach here!"); } Here’s what I have so far. It works, but the more I read about using exceptions for flow control the less I like it, so I want to see if there are alternatives. Remove Method public void remove(GameObject go) { //add to removedList //flag as removed //throw an exception if removing self from inside an updateEvent } Game Loop for(GameObject go : objectList) { try { if (!go.removed) { go.updateEvent(); } else { //object is scheduled to be removed, do nothing } } catch(ObjectRemovedException e) { //control has been transferred back to the game loop //no need to do anything here } } // now remove the objects that are in removedList from objectList 2 questions: Am I correct in assuming that the only way to implement the stop-right-away part of the remove method as described above is by throwing a custom exception and catching it in the game loop? (I know, using exceptions for flow control is like goto, which is bad. I just can’t think of another way to do what I want!) For the removal from the list itself, it is possible for one object to remove one that is farther down on the list. Currently I’m checking a removed flag before executing any code, and at the end of each pass removing the objects to avoid concurrent modification. Is there a better, preferably instant/non-polling way to do this?

    Read the article

  • Java: JGraphT: Iterate through nodes

    - by Rosarch
    I'm trying to iterate through all nodes, so I can print them out for graphviz. What is the best way to do that using the JGraphT library? public static void main(String[] args) { UndirectedGraph<String, DefaultEdge> g = new SimpleWeightedGraph<String, DefaultEdge>(DefaultEdge.class); String odp = "ODP"; String cck = "CCK"; String mfe = "MFE"; g.addVertex(odp); g.addVertex(cck); g.addVertex(mfe); g.addEdge(odp, cck); g.addEdge(odp, mfe); } Also, how do I add edge weights? Edit: This seems to work pretty well. But is there a better way? Set<DefaultEdge> edges = g.edgeSet(); for (DefaultEdge e : edges) { gv.addln(String.format("\"%s\" -> \"%s\"", g.getEdgeSource(e), g.getEdgeTarget(e))); }

    Read the article

  • ConcurentModificationException in Java HashMap

    - by Bear
    Suppose I have two methods in my classes, writeToMap() and processKey() and both methods are called by multiple threads. writeToMap is a method to write something in hashmap and processKey() is used to do sth based on the keySet of HashMap. Inside processKey, I first copy the originalMap before getting the key set. new HashMap<String, Map<String,String>(originalMap).get("xx").keySet(); But I am still getting ConcurrentModificationException even though I always copy the hashmap. Whats the problem?

    Read the article

  • Java reflection framework and security

    - by Jijoy
    Hi , Assume I have a singleton class in an external lib to my application. But still I can create instances of that particular class using reflection. Like this Class clas = Class.forName(Private.class.getName()); for(Constructor c : clas.getDeclaredConstructors()){ c.setAccessible(true); Private p = (Private) c.newInstance(); System.out.println(p); } How can I restrict this ? . Thanks J

    Read the article

  • JAVA: Can't get context parameters in Filter

    - by DaTval
    Hello, I have a filter and parameters in web.xml web.xml is like this: <filter> <description> </description> <display-name>AllClassFilter</display-name> <filter-name>AllClassFilter</filter-name> <filter-class>com.datval.homework.AllClassFilter</filter-class> <init-param> <param-name>DB_URL</param-name> <param-value>jdbc:derby:C:/Users/admin/workspace/homework03/homework/databases/StudentsDB;create=true</param-value> </init-param> <init-param> <param-name>DB_DIALECT</param-name> <param-value>org.hibernate.dialect.DerbyDialect</param-value> </init-param> <init-param> <param-name>DB_DRIVER</param-name> <param-value>org.apache.derby.jdbc.EmbeddedDriver</param-value> </init-param> </filter> mapping is working well. But I can't get this parameters in my filter. public void init(FilterConfig config) throws ServletException { // TODO Auto-generated method stub debugMessage = config.getInitParameter("debugMessage"); ctx = config.getServletContext(); } public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { // TODO Auto-generated method stub // place your code here ctx.log("Start - " + debugMessage); String myDbUrl = ctx.getInitParameter("DB_URL"); String DB_DIALECT = ctx.getInitParameter("DB_DIALECT"); String DB_DRIVER = ctx.getInitParameter("DB_DRIVER"); Map<String,String> pr = new HashMap<String,String>(); pr.put("hibernate.connection.url", myDbUrl); pr.put("hibernate.dialect", DB_DIALECT); pr.put("hibernate.connection.driver_class", DB_DRIVER); EntityManagerFactory emf = Persistence.createEntityManagerFactory("students",pr); EntityManager em = emf.createEntityManager(); request.setAttribute("em", em); chain.doFilter(request, response); em.close(); ctx.log("end - " + debugMessage); } I have checked and myDbUrl is null. What I'm doing wrong? Any idea? Sorry about code, I will change it later :)

    Read the article

  • Returning string in java using 3 parameters

    - by user2905118
    Need to write a method describePerson() that takes 3 parameters, a String giving a person’s name, a boolean indicating their gender (true for female, false for male), and an integer giving their age. The method should return a String formatted as in the following examples: Lark is female. She is 2 years old. Or Jay is male. He is 1 year old. I am not sure how to write it correctly (my code): int describePerson(String name, boolean gender, int age) { String words=""; if(gender==true) return (name + "is "+gender+". "+"She is"+age+ "years old.); else return (name + "is "+gender+". "+"She is"+age+ "years old.); } The outcome "year" and "years" is also differs, but i don't know how to make it correct..

    Read the article

< Previous Page | 309 310 311 312 313 314 315 316 317 318 319 320  | Next Page >