java - JPanel 没有显示它的其余部分

Question

我有一个带有按钮的框架和一个名为面板的 JPanel，我想在单击按钮后向我的面板添加一个内部面板。但是这可是有问题的!因为在添加第二个面板后，它没有添加任何其他面板。

代码

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.AbstractButton;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import java.awt.GridBagLayout;
import java.awt.GridBagConstraints;
import java.awt.GridLayout;
import javax.swing.JTextField;


public class DrawImages extends JFrame{
    
    int i;
    public DrawImages() {
        JButton btnNewButton = new JButton("New button");
        i = 0;
        getContentPane().add(btnNewButton, BorderLayout.SOUTH);
        setMinimumSize(new Dimension(1000,150));
        final JPanel panel = new JPanel();
        panel.setSize(995, 145);
        getContentPane().add(panel, BorderLayout.CENTER);
        panel.setLayout(null);
        

        final JLabel lblNewLabel = new JLabel("New label");
        lblNewLabel.setBounds(0, 0, 46, 14);
        panel.add(lblNewLabel);
        
        btnNewButton.addActionListener(new ActionListener() 
            public void actionPerformed(ActionEvent paramActionEvent) {
                JPanel panel_1 = new JPanel();
                //getContentPane().add(panel_1, BorderLayout.NORTH);
                panel_1.setLayout(null);
                JLabel imagelable = new JLabel(new ImageIcon("c:\\good.jpg"));
                imagelable.setBounds(70, 5, 105, 65);
                panel_1.add(imagelable);
                
                JLabel lblNewLabel_4 = new JLabel("Up Label");
                lblNewLabel_4.setBounds(5, 5, 65, 35);
                panel_1.add(lblNewLabel_4);
                
                JLabel lblNewLabel_2 = new JLabel("Down Label");
                lblNewLabel_2.setBounds(5, 25, 65, 65);
                panel_1.add(lblNewLabel_2);
                lblNewLabel.setText(""+i);
                panel_1.setBounds(5+170*i, 5, 170+170*i, 70);
                panel.add(panel_1);
                i++;
            }
        });
        panel.setMinimumSize(new Dimension(995,150));
    }

    public static void main(String[]args)
    {
        DrawImages drawImages = new DrawImages();
        drawImages.setVisible(true);
    }
}

Answer 1

问题在于语句:

panel_1.setLayout(null);

panel_1 没有任何首选大小，因此不会出现(或将显示为一个小点)。

Swing 旨在使用布局管理器。在这种特殊情况下，您可以使用 GridLayout。

阅读:Doing Without a Layout Manager