Question

我发现当我在JPanel中使用removeAll（），然后尝试通过add（）添加新内容（例如简单的文本JLabel）时，原始内容会被清除，但新内容不会出现。是的，我记得之后在JPanel上订购了repaint（）操作，是的，我正在SwingUtilities.invokeLater（）中进行这些操作。但是如果我保持框架不变，则不会出现JPanel的新内容。

但是，如果我手动调整框架大小，则会显示内容。

有人可以就如何让内容自行显示给我任何建议吗？感谢。

示例代码：

public class SimpleTester extends JFrame implements WindowListener {

private static final long serialVersionUID = 6768852132139940161L;
private JPanel panel;

public SimpleTester() throws HeadlessException {
    super("SimpleTester");
    panel = new JPanel();
    panel.setLayout(new BoxLayout(panel, BoxLayout.X_AXIS));
    panel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
    panel.add(Box.createRigidArea(new Dimension(60, 60)));
    this.getContentPane().setLayout(new BoxLayout(this.getContentPane(), BoxLayout.Y_AXIS));
    this.getContentPane().add(panel);
    this.addWindowListener(this);
    this.pack();
}

public static void main(String[] args) {
    SimpleTester tester = new SimpleTester();
    tester.setVisible(true);
    final String alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    int pos = 0;
    while(true) {
        SwingUtilities.invokeLater(new Replacer(tester.mainPanel(), new JLabel(alphabet.substring(pos, pos+1))));
        pos++;
        if(pos>=alphabet.length()) {
            pos = 0;
        }
        synchronized(tester) {
            try {
                tester.wait(3000L);
            } catch (InterruptedException e) {
                System.exit(0);
            }
        }
    }
}

@Override
public void windowActivated(WindowEvent arg0) {
    // TODO Auto-generated method stub

}

@Override
public void windowClosed(WindowEvent arg0) {
    // TODO Auto-generated method stub

}

@Override
public void windowClosing(WindowEvent arg0) {
    System.exit(0);
}

@Override
public void windowDeactivated(WindowEvent arg0) {
    // TODO Auto-generated method stub

}

@Override
public void windowDeiconified(WindowEvent arg0) {
    // TODO Auto-generated method stub

}

@Override
public void windowIconified(WindowEvent arg0) {
    // TODO Auto-generated method stub

}

@Override
public void windowOpened(WindowEvent arg0) {
    // TODO Auto-generated method stub

}

public JPanel mainPanel() {
    return panel;
}

public static class Replacer implements Runnable {

    private JPanel holder;
    private Component [] fillers;

    public Replacer(JPanel host, Component... contents) {
        holder = host;
        fillers = contents;
    }

    @Override
    public void run() {
        holder.removeAll();
        holder.repaint();
        if(fillers==null) {             
        } else {
            for(int x=0;x<fillers.length;x++) {
                holder.add(fillers[x]);
            }
            holder.repaint();
        }
    }

}

}

removeAll（）后重新填充JPanel

0 个答案: