我的程序應該啓動第二個JFrame並在點擊該按鈕時打印語句,但它總是啓動三個JFrame並打印三條語句。我需要它只打印出一條語句並啓動一個Jframe。下面是代碼:如何在不啓動Java中的更多JFrame的情況下使用JFrame按鈕啓動第二個JFrame?
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;
@SuppressWarnings("serial")
public class Test extends JPanel implements ActionListener {
JButton button = new JButton();
String buttonString = "Buttontext";
public Test() {
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
button.setText("Buttontext");
button.setCursor(Cursor.getDefaultCursor());
button.setMargin(new Insets(0, 0, 0, 0));
button.setBounds(700, 400, 100, 20);
button.setActionCommand(buttonString);
button.addActionListener(this);
this.add(button);
}
public static void createandshowGUI() {
JFrame frame = new JFrame("Frame");
frame.getContentPane().setBackground(Color.white);
Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
frame.setSize(dim.width, dim.height);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new Test());
frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createandshowGUI();
}
});
}
public void actionPerformed(ActionEvent e) {
if (buttonString.equals(e.getActionCommand())) {
System.out.println("creating a new frame");
newframe();
}
}
public void newframe() {
JFrame frame2 = new JFrame();
Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
frame2.setSize(dim.width/2, dim.height/2);
frame2.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame2.setExtendedState(JFrame.MAXIMIZED_BOTH);
frame2.setVisible(true);
}
}