actionlistener java,ActionListener中的Java Swing问题

//GUI.java

public class GUI extends JFrame implements ActionListener {

private static final long serialVersionUID = 870343916997182570L;

private JPanel btmPanel;

public GUI(String arg0) throws HeadlessException {

super(arg0);

createGUI();

}

private void createGUI() {

setSize(WIDTH, HEIGHT);

setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

setLayout(new BorderLayout());

//ResultPanel rslt = new ResultPanel();

//this.getContentPane().add(rslt.createPanel(), BorderLayout.CENTER);

btmPanel = new JPanel();

btmPanel.setBackground(Color.LIGHT_GRAY);

btmPanel.setLayout(new FlowLayout());

JButton blueSearch = new JButton(“Search”);

blueSearch.setBackground(Color.WHITE);

blueSearch.addActionListener(this);

btmPanel.add(blueSearch);

JButton blackChart = new JButton(“Chart”);

blackChart.setBackground(Color.WHITE);

blackChart.addActionListener(this);

btmPanel.add(blackChart);

this.getContentPane().add(btmPanel, BorderLayout.SOUTH);

}

@Override

public void actionPerformed(ActionEvent e) {

String buttonString = e.getActionCommand();

if (buttonString.equals(“Search”)) {

ResultPanel rslt = new ResultPanel();

this.getContentPane().add(rslt.createPanel(), BorderLayout.CENTER);

}

}

}

//ResultPanel.java

public class ResultPanel extends JPanel implements ActionListener {

private static final long serialVersionUID = -7851502165390304971L;

private JPanel textPanel;

private JTextArea textDisplay;

public ResultPanel() {

textPanel = new JPanel();

textDisplay = new JTextArea(“Text Area:”);

}

public JPanel createPanel() {

textDisplay.setEditable(true);

textPanel.setBackground(Color.LIGHT_GRAY);

textPanel.setLayout(new BorderLayout());

textPanel.add(textDisplay,BorderLayout.CENTER);

return textPanel;

}

@Override

public void actionPerformed(ActionEvent e) {

}

}

I have two buttons on the main frame, and I hope to change the panel when I press the button.

The question is that the code in “actionPerformed” doesn’t work,

but it works well if I put them in the creatGUI()….(see the marked section).

Is that anything wrong ?

解决方案

Just call pack(); after you add the panel. This will get the JFrame to show the update.

if (buttonString.equals(“Search”)) {

ResultPanel rslt = new ResultPanel();

this.getContentPane().add(rslt.createPanel(), BorderLayout.CENTER);

pack();

}