Search Results

Search found 44020 results on 1761 pages for 'java date'.

Page 328/1761 | < Previous Page | 324 325 326 327 328 329 330 331 332 333 334 335  | Next Page >

  • object construct a class of objects in java

    - by Mgccl
    There is a super class, A, and there are many subclasses, B,C,D... people can write more subclasses. Each of the class have the method dostuff(), each is different in some way. I want an object that constructs any object that belong to A or any of it's subclass. For example I can pass the name of the subclass, or a object of that class, and it will construct another object of the class. Of course I can write A construct(A var){ stuff = var.dostuff(); domorestuff(stuff) return new A(stuff); } B construct(B var){ stuff = var.dostuff(); domorestuff(stuff) return new B(stuff); } C construct(C var){ stuff = var.dostuff(); domorestuff(stuff) return new C(stuff); } but this is not efficient. I have to write a few new lines every time I make a new subclass. It seems I can't use generics either. Because I can't use dostuff() on objects not in any of the subclass of A. What should I do in this situation?

    Read the article

  • How to rotate an image properly in JPanel (Java)

    - by Bruce
    Hi guys, I'm working on rotating a loaded image. I set the graphics on a JPanel and then use standard AffineTransform in order to rotate it, say, 45 degrees. Unfortunately, the image is being cut, if it exceeds the panel area. How may I force JPanel to add scrolls to itself (while loading an image file, I would like to adjust the size of JPanel by adding the scrolls, without adjusting the size of JFrame). Or, in other words, how to correctly rotate the whole image? Thank you in advance for the reply!

    Read the article

  • Well written open source java projects

    - by Algorist
    I want to improve my design and programming skills by understanding design & code of open source projects. I downloaded hadoop,groovy but they are very difficult to follow. I am not having a clue of how to follow this code without having a high level overview of the design. Any suggestions?? Thank you.

    Read the article

  • Java consistent synchronization

    - by ring0
    We are facing the following problem in a Spring service, in a multi-threaded environment: three lists are freely and independently accessed for Read once in a while (every 5 minutes), they are all updated to new values. There are some dependencies between the lists, making that, for instance, the third one should not be read while the second one is being updated and the first one already has new values ; that would break the three lists consistency. My initial idea is to make a container object having the three lists as properties. Then the synchronization would be first on that object, then one by one on each of the three lists. Some code is worth a thousands words... so here is a draft private class Sync { final List<Something> a = Collections.synchronizedList(new ArrayList<Something>()); final List<Something> b = Collections.synchronizedList(new ArrayList<Something>()); final List<Something> c = Collections.synchronizedList(new ArrayList<Something>()); } private Sync _sync = new Sync(); ... void updateRunOnceEveryFiveMinutes() { final List<Something> newa = new ArrayList<Something>(); final List<Something> newb = new ArrayList<Something>(); final List<Something> newc = new ArrayList<Something>(); ...building newa, newb and newc... synchronized(_sync) { synchronized(_sync.a) { _synch.a.clear(); _synch.a.addAll(newa); } synchronized(_sync.b) { ...same with newb... } synchronized(_sync.c) { ...same with newc... } } // Next is accessed by clients public List<Something> getListA() { return _sync.a; } public List<Something> getListB() { ...same with b... } public List<Something> getListC() { ...same with c... } The question would be, is this draft safe (no deadlock, data consistency)? would you have a better implementation suggestion for that specific problem? update Changed the order of _sync synchronization and newa... building. Thanks

    Read the article

  • Stopping looping thread in Java

    - by halfwarp
    I'm using a thread that is continuously reading from a queue. Something like: public void run() { Object obj; while(true) { synchronized(objectsQueue) { if(objectesQueue.isEmpty()) { try { objectesQueue.wait(); } catch (InterruptedException e) { e.printStackTrace(); } obj = objectesQueue.poll(); } } // Do something with the Object obj } } What is the best way to stop this thread? I see two options: 1 - Since Thread.stop() is deprecated, I can implement a stopThisThread() method that uses a n atomic check-condition variable. 2 - Send a Death Event object or something like that to the queue. When the thread fetches a death event it exists. I prefer the 1st way, however, I don't know when to call the stopThisThread() method, as something might be on it's way to the queue and the stop signal can arrive first (not desirable). Any suggestions?

    Read the article

  • Revalidate and repaint - Java Swing

    - by bosra
    I have a JPanel that I am adding JLabel's to. I then want to remove all the JLabels and add some new ones. So I do the following: panel.removeAll();panel.repaint(); panel.add(new JLabel("Add something new"); panel.revalidate(); This works fine. My problem arises when I start a new thread after this like: panel.removeAll();panel.repaint(); (1)panel.add(new JLabel("Add something new"); panel.revalidate(); //new thread to start - this thread creates new JLabels that should appear under (1) firstProducer.start(); try { firstProducer.join(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } Then the output from the original JLabels is still visible. I have read that the revalidate process is a long running task and hence the firstProducer thread is getting started while the revalidation is going on and a conflict is arising. What is the best way to deal with this?

    Read the article

  • Programming error in Java Socket

    - by Akhil K Nambiar
    Can you tell me what is the error in this code? Socket socket = new Socket(hostname, port); PrintWriter out = new PrintWriter(socket.getOutputStream(), true); //DataInputStream is = new DataInputStream(socket.getInputStream()); out.println("hi"); System.out.print(in.readLine()); The Server Socket program is written in .Net and it echoes back the data. The data is sent successfully but could not be retrieved properly. I tried the same by using the linux command nc 192.168.1.6 8425 (enter) Hi (Sent data) Hi (recieved data) When I checked the code the data is found to have sent as byteStream in .Net. Is that a problem. In that case what modification should I make.

    Read the article

  • Please clarify a few points concerning Java Servlets

    - by EugeneP
    suppose, I use Tomcat as a web container. Is it true that once all the servlets found in a web-app/WEBAPPNAME are init(IALIZED) then every change of a Servlet's property will be seen to every session. So session 1 changes a property userName of a Servlet1 from "user1" to "user2" session 1 is closed. session 2 starts. It will see "user2" as the only value of Servlet1.userName property?? Any change of a Servlet's field will be seen to all subsequent sessions? Are servlets singletons, aren't they?

    Read the article

  • Java copyOf method problem with an Array of Objects

    - by Greg
    elementData = Arrays.copyOf(elementData, newCapacity); Gives error: "The method copyOf(Object[], int) is undefined for the type Arrays" This was not a problem on my home computer, but at my school's it gives the error above. I'm guessing it's running an older JRE version - any workaround? Thanks

    Read the article

  • Java generics question

    - by user247866
    So I have 3 classes. Abstract class A Class B extends class A independent Class C In class D that contains the main method, I create a list of instances of class B List<B> b = methodCall(); // the method returns a list of instances of class B Now in class C I have one method that is common to both A and B, and hence I don't want to duplicate it. I want to have one method that takes as input an instance of class A, as follows: public void someMethod(List<A> a) However, when I do: C c = new C(); c.someMethod(b); I get an error that some-method is not applicable for the argument List<B>, instead it's expecting to get List<A>. Is there a good way to fix this problem? Many thanks!

    Read the article

  • Garbage Collection Java

    - by simion
    On the slides i am revising from it says the following; Live objects can be identified either by maintaining a count of the number of references to each object, or by tracing chains of references from the roots. Reference counting is expensive – it needs action every time a reference changes and it doesn’t spot cyclical structures, but it can reclaim space incrementally. Tracing involves identifying live objects only when you need to reclaim space – moving the cost from general access to the time at which the GC runs, typically only when you are out of memory. I understand the principles of why reference counting is expensive but do not understand what "doesn’t spot cyclical structures, but it can reclaim space incrementally." means. Could anyone help me out a little bit please? Thanks

    Read the article

  • Java generics question with wildcards

    - by Sean
    Just came across a place where I'd like to use generics and I'm not sure how to make it work the way I want. I have a method in my data layer that does a query and returns a list of objects. Here's the signature. public List getList(Class cls, Map query) This is what I'd like the calling code to look like. List<Whatever> list = getList(WhateverImpl.class, query); I'd like to make it so that I don't have to cast this to a List coming out, which leads me to this. public <T> List<T> getList(Class<T> cls, Map query) But now I have the problem that what I get out is always the concrete List<WhateverImpl> passed in whereas I'd like it to be the Whatever interface. I tried to use the super keyword but couldn't figure it out. Any generics gurus out there know how this can be done?

    Read the article

  • Distinguish between a single click and a double click in Java

    - by user552279
    Hi, I search the forum and see this codes: public void mouseClicked(MouseEvent e) { if (e.getClickCount() == 2) { System.out.println(" and it's a double click!"); wasDoubleClick = true; } else { Integer timerinterval = (Integer) Toolkit.getDefaultToolkit().getDesktopProperty( "awt.multiClickInterval"); timer = new Timer(timerinterval.intValue(), new ActionListener() { public void actionPerformed(ActionEvent evt) { if (wasDoubleClick) { wasDoubleClick = false; // reset flag } else { System.out.println(" and it's a simple click!"); } } }); timer.setRepeats(false); timer.start(); } } but the code runs incorrectly(Sometime it prints out " and it's a single click!" 2 times . It should print out " and it's a double click!"). Can anybody show me why? or can you give me some better ways to do this? Thank you!

    Read the article

  • Java JPA @OneToMany neededs to reciprocate @ManyToOne?

    - by bguiz
    Create Table A ( ID varchar(8), Primary Key(ID) ); Create Table B ( ID varchar(8), A_ID varchar(8), Primary Key(ID), Foreign Key(A_ID) References A(ID) ); Given that I have created two tables using the SQL statements above, and I want to create Entity classes for them, for the class B, I have these member attributes: @Id @Column(name = "ID", nullable = false, length = 8) private String id; @JoinColumn(name = "A_ID", referencedColumnName = "ID", nullable = false) @ManyToOne(optional = false) private A AId; In class A, do I need to reciprocate the many-to-one relationship? @Id @Column(name = "ID", nullable = false, length = 8) private String id; @OneToMany(cascade = CascadeType.ALL, mappedBy = "AId") private List<B> BList; //<-- Is this attribute necessary? Is it a necessary or a good idea to have a reciprocal @OneToMany for the @ManyToOne? If I make the design decision to leave out the @OneToMany annotated attribute now, will come back to bite me further down.

    Read the article

  • Regex to match pattern with subdomain in java gives issues

    - by Ramesh
    I am trying to match the sub domain of an url using http://([a-z0-9]*.)?example.com/.* which works perfectly for these cases. http://example.com/index.html http://test.example.com/index.html http://test1.example.com/index.html http://www.example.com/122/index.html But the problem is it matches for this URL too. http://www.test.com/?q=http://example.com/index.html if an URL with another domain has the URL in path it matches.Can any one tell me how to match for current domain only. getting the host will work but i need to match full URL.

    Read the article

  • Java Recursion Triangle Standing on Tip

    - by user1629075
    I was wondering how to create triangle out of asterisks on its tip rather than on its base. I have the code for making it stand on its base: public static String printTriangle (int count) { if( count <= 0 ) return ""; String p = printTriangle(count - 1); p = p + "*"; System.out.print(p); System.out.print("\n"); return p; } But then I'm stuck on how to have the greatest number of stars on the top, and then the next least, and so on. I was thinking something along the terms of having (count - p) to have the input of rows be subtracted from the amount of decrease, but then i was confused by this idea because p is string. EDIT: I tried changing the position of printTriangle(count - 1) using my original method without iterations and got 1 star per each line; how can I fix this? public class triangles { public static void main(String[] args) { printTriangle(5); } public static String printTriangle (int count) { if( count <= 0 ) return ""; String p = ""; p = p + "*"; System.out.print(p); System.out.print("\n"); p = printTriangle(count - 1); return p; } }

    Read the article

  • Can I avoid repeating myself in this situation (Java)

    - by UltimateGuy
    if (openFile == null) { new AppFileDialog().chooseFile("Save", appFrame); } if (openFile == null) { return; } Here I need to check to see if the user has already chosen a file. If not, they are given a prompt to. If the file is still null, the function returns without saving. The problem is the two identical if statements, can I avoid it? I take DRY very seriously, but at the same time KISS. Ideally the two go hand in hand, but in a situation like this, it seems they are mutually exclusive.

    Read the article

  • How to profile object creation in Java?

    - by gooli
    The system I work with is creating a whole lot of objects and garbage collecting them all the time which results in a very steeply jagged graph of heap consumption. I would like to know which objects are being generated to tune the code, but I can't figure out a way to dump the heap at the moment the garbage collection starts. When I tried to initiate dumpHeap via JConsole manually at random times, I always got results after GC finished its run, and didn't get any useful data. Any notes on how to track down excessive temporary object creation are welcome.

    Read the article

  • Java Thread - Memory consistency errors

    - by Yatendra Goel
    I was reading a Sun's tutorial on Concurrency. But I couldn't understand exactly what memory consistency errors are? I googled about that but didn't find any helpful tutorial or article about that. I know that this question is a subjective one, so you can provide me links to articles on the above topic. It would be great if you explain it with a simple example.

    Read the article

  • How to concatenate int values in java?

    - by Shamli
    hi, I have the following values: int a=1; int b=0; int c=2; int d=2; int e=1; How do i concatenate these values so that i end up with a String that is 10221; please note that multiplying a by 10000, b by 1000.....and e by 1 will not working since b=0 and therefore i will lose it when i add the values up. Thnks you in advance.

    Read the article

< Previous Page | 324 325 326 327 328 329 330 331 332 333 334 335  | Next Page >