单击按钮将ImageIcon添加到已经可见的GUI中

Question

I'm a bit confused as to why my program isn't working. I am trying to add a image to the frame when I click the button. I have verified in java that the file exists and it can find the photo. I have also verified that the button works. But when I compile and click the button it does nothing at all...if someone could guide me in the correct direction it would be much appreciated.

package gamePractice;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingConstants;

public class window {

    public static void main(String[] args){
        JFrame frame = new JFrame("ex");

        JPanel panel = new JPanel();
        JButton button = new JButton();
        button.setText("Press Me");

        panel.add(button);
        frame.add(panel);
        frame.setSize(300, 300);
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);

        button.addActionListener(new ActionListener() {
               @Override
            public void actionPerformed(ActionEvent e) {
                     if(e.getSource() == button) {
                        ImageIcon img = new ImageIcon(getClass().getResource("t.jpg"));
                        JLabel stickLabel = new JLabel("yes", img, SwingConstants.CENTER);
                        JPanel panel2 = new JPanel();
                        panel2.add(stickLabel);
                        frame.add(panel2);
                      }
               }
         });
    }
}

Answer 1

• JFrame uses BorderLayout (only one JComponent can be placed to CENTER area)
• your ActionListener replaces JPanel panel = new JPanel(); with JPanel panel2 = new JPanel(); , then JButton button = new JButton(); can dissapears,

then there are two options, note JPanel uses FlowLayout

1. (correct) to add JLabel to JPanel , change LayoutManager to JPanel by using BorderLayout , load ImageIcon to the local variable, inside ActionListener to call JLabel.setText() and JLabel.setIcon()

2. (replacing content) call revalidate(); and repaint(); to JFrame , but JPanel panel = new JPanel(); with JButton button = new JButton(); can dissapears forever,

Answer 2

You are adding Components to an already visible container - you need to call let the LayoutManager know about the change by calling revalidate followed by repaint

panel2.add(stickLabel);
frame.add(panel2);
panel2.revalidate();
panel2.repaint();