paintComponent not being called at the right time

问题

I'm trying to write an app that goes something like this:
- Display a dialog
- When user clicks OK, close dialog, go to main app

Here are the relevant code snippets:

public class Owari extends JPanel implements ActionListener, MouseListener, Runnable {

// FIELDS
JFrame frame;
JTextField IP;
String IPAddress;

static final int SERVER_MODE = 0;
static final int CLIENT_MODE = 1;
int mode;

OwariBoard board;

  public static void main( String[] args ) {
    SwingUtilities.invokeLater( new Owari() );
  }

  Owari() {
    setPreferredSize( new Dimension( WIDTH, HEIGHT ) );
    board = new OwariBoard();
  }

  void main() {
    this.addMouseListener( this );
    frame.dispose();
    frame = new JFrame( "Owari" );
    frame.setContentPane( this );
    frame.pack();
    frame.setVisible(true);
    if ( mode == SERVER_MODE ) {
      server();
    }
    if ( mode == CLIENT_MODE ) {
      client();
    }
  }

  public void run() {
    frame = new JFrame( "Owari" );
    frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
    JPanel init = new JPanel( new GridBagLayout() );
    frame.setContentPane( init );

    add some components to the init panel including a button with
    this as its actionListener and OK as its command.
    frame.pack();
    frame.setVisible( true );
  }


  public void actionPerformed( ActionEvent e ) {
    if ( e.getActionCommand().equals( "Client" ) ) {
      mode = CLIENT_MODE;
      IP.setVisible( true );
    }
    else if ( e.getActionCommand().equals( "Server" ) ) {
      mode = SERVER_MODE;
      IP.setVisible( false );
    }
    else {
      IPAddress = IP.getText();
      main();
    }
  }

  public void paintComponent( Graphics g ) {
    super.paintComponent( g );
    System.out.println( "painting" );
    do some paintin
  }

  void server() {
    frame.setTitle( "Owari Server" );
    try {
    server = new ServerSocket( 666 );
    socket = server.accept();
    initIO();
    } catch ( IOException e ) {}
    yourTurn = true;
    System.out.println( "Got to end of server()" ); // At this point, the window
                                                       DOES get painted

What happens is the following:
The initial dialog displays:
I click the OK button. The main window gets resized to the preferred size of the main app but it doesn't get painted, it's just transparent (shown here with this page as the background, heh):
http://imgur.com/6Ssij.jpg

I can tell the paintComponent method hasn't been called because "painting" isn't printed to the console. However, "got to this point in the program" DOES get printed, so the program isn't hanging, it's just not calling paintComponent. Then when I launch a client and connect, the app finally gets painted, and "painting" and "got a client" get printed to the console. Also later on in the app, calls to repaint() are delayed (ie paintComponent is actually called later in the program than when the call to repaint() is made).

I also tried replacing the initial dialog using sthing along the lines of

public void main
  frame.getRootPane.removeAll()
  frame.setContentPane(this)
  frame.getRootPane().revalidate()
  frame.pack()

Exact same result.

tl;dr paintcomponent isn't being called when i want it to, what do?

Bumping for some more info: the call to repaint() is done before the call to sever.accept() So why does it not repaint() before hanging at the server.accept() call?

回答1:

openasocketandwaitforaclient

Your code is executing in the Event Dispatch Thread so the blocking socket is preventing the GUI from repainting itself.

YOu need to use a separate Thread for the socket. Read the section from the Swing tutorial on Concurrency for an explanation and a solution.

回答2:

your code seems to work so, maybe you should try to invoke the repaint() methode of you frame after resizing this frame.

Anhuin

来源：https://stackoverflow.com/questions/4441700/paintcomponent-not-being-called-at-the-right-time

标签

java

swing

paintcomponent