我正在尝试为我的Java应用程序编写自定义JFrame和JPanel。目前,我只想在屏幕中间有一个启动按钮的JPanel。所以,这里是我的代码:为什么我的JFrame保持空白,如果我继承JPanel和JFrame?
package gui;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JFrame;
@SuppressWarnings("serial")
public class SubitizingFrame extends JFrame implements KeyListener {
public SubitizingFrame() {
super("Subitizing");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
addKeyListener(this);
add(new LaunchPanel());
pack();
setVisible(true);
}
public void keyPressed(KeyEvent e) {
if(e.getKeyCode() == KeyEvent.VK_F5)
System.out.println("F5 pressed");
}
public void keyReleased(KeyEvent e) {
}
public void keyTyped(KeyEvent e) {
}
}
,这里是我的面板:
package gui;
import instructions.Settings;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JPanel;
@SuppressWarnings("serial")
public class LaunchPanel extends JPanel implements ActionListener {
private JButton startButton;
public LaunchPanel() {
int width = Settings.getScreenSizeX(), height = Settings.getScreenSizeY();
setPreferredSize(new Dimension(width, height));
setLayout(null);
startButton = new JButton("Start");
startButton.setLocation((width/2) - (startButton.getWidth()/2), (height/2) - (startButton.getHeight()/2));
add(startButton);
}
public void actionPerformed(ActionEvent arg0) {
// TODO Auto-generated method stub
}
}
但应用程序启动时,我看不到任何东西。只是一个大灰色的屏幕。
+1建议不使用空布局的任何答案都需要提高。 – camickr