我无法弄明白。我尝试过交换我的createWindow（）和createButton（）方法，并尝试调用repaint（）。我也试过分层，以便首先制作JPanel，然后是JFrame，然后将JPanel附加到JFrame。 我确保在将所有元素添加到JFrame后添加setVisible（true），现在JPanel根本不会显示。这是我的Window类和绘画类：
public class Window扩展了JFrame {
private JPanel design;
private Container win;
private JFrame window,popUp;
private JButton button,button2,saveButton,loadButton,quitButton;
private JOptionPane j;
private String name;
Window(){ //Constructor
initial();
createWindow();
createButton();
actionAddButton();
combinePanel();
setVisible(true);
}
private void initial(){
//window = new JFrame("Family Tree");
button = new JButton("Add Person");
button2 = new JButton("Delete Person");
saveButton = new JButton("Save");
loadButton = new JButton("Load");
quitButton = new JButton("Quit");
j = new JOptionPane();
name = null;
win = getContentPane();
}
public JButton getButton2(){
return button2;
}
private void createWindow(){
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setTitle("Family Tree");
setSize(650, 650);
setLocationRelativeTo(null);
//setVisible(true);
// win.setLayout(new GridLayout(1,1));
//Adds paint to container
}
private void combinePanel(){
Painting panel = new Painting();
add(panel);
}
private void createButton(){
// Container panel = getContentPane(); // content panel area where child components placed
//panel.add(button,BorderLayout.LINE_START);
/*getContentPane returns contentPane object*/
GroupLayout layout = new GroupLayout(win);
// GroupLayout layout = new GroupLayout(window.getContentPane());
layout.setAutoCreateContainerGaps(true); //Dont have to specify gaps
layout.setAutoCreateGaps(true);
win.setLayout(layout); //NEED THIS
layout.setVerticalGroup( //setHorizontalGroup(Group group)
layout.createSequentialGroup().addComponent(button)
.addComponent(button2)
.addComponent(saveButton) .addComponent(quitButton)
.addComponent(loadButton)
);
layout.setHorizontalGroup(
/*createParallelGroup() returns new parallel group*/
layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(GroupLayout.Alignment.CENTER)
.addComponent(button).addComponent(button2)
.addComponent(saveButton).addComponent(loadButton)
.addComponent(quitButton))
);
repaint();
}
private void actionAddButton(){
button.addActionListener(new ActionListener() { //Action listener for button
@Override //
public void actionPerformed(ActionEvent event){ //Want own action preformed
name = JOptionPane.showInputDialog(new PopUp(),"Enter Name");
}
});
}
这是我的绘画班：
公共类绘画扩展了JPanel {
Painting(){
setBackground(Color.GREEN);
}
@Override
public void paintComponent(Graphics g){
super.paintComponent(g);
Graphics2D divider = (Graphics2D) g; //casting object
divider.draw(new Line2D.Double(180, 0, 180, 650));
}
感谢所有帮助。感谢