JPanel z-ordering

Question

我有一个JPanel基地，我将在其中放置其他JPanel个项目。我想在另一个JPanel项目的顶部显示一个JPanel。

我尝试使用下面的代码，但它没有用。

package test;

import java.awt.Color;
import java.awt.HeadlessException;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class JPanelParent extends JFrame
{

    public JPanelParent() throws HeadlessException {
        JPanel nPanel = getNode(10,10,20,20, Color.red,1);
        JPanel nPanel2 = getNode(20,20,20,20, Color.yellow,2);
        JPanel nPanel3 = getNode(30,30,20,20, Color.green,3);
        add(nPanel);
        add(nPanel2);
        add(nPanel3);
    }

    public JPanel getNode(int i, int i1, int j, int j1, Color color, int zOrder){
        JPanel nodePanel = new JPanel();
        nodePanel.setBackground(color);
        nodePanel.setBounds(i,i1,j,j1);
        nodePanel.setOpaque(true);
        nodePanel.setLayout(null);
        return nodePanel;
    }


    public static void main(String argv[]){
        JPanelParent jpp = new JPanelParent();
        jpp.setVisible(true);
        jpp.setSize(300,300);
        jpp.setBackground(Color.black);
    }
}

由于

Answer 1

您可以使用JLayeredPane。查看更多How to Use JLayeredPane

public JPanelParent() throws HeadlessException {
    JPanel nPanel = getNode(10, 10, 20, 20, Color.red, 1);
    JPanel nPanel2 = getNode(20, 20, 20, 20, Color.yellow, 2);
    JPanel nPanel3 = getNode(30, 30, 20, 20, Color.green, 3);
    JLayeredPane pane = new JLayeredPane();
    pane.add(nPanel, new Integer(1));
    pane.add(nPanel2, new Integer(2));
    pane.add(nPanel3, new Integer(3));

    setContentPane(pane);
    getContentPane().setBackground(Color.BLACK);
}

注意：传递的Integer值是图层顺序。数字越高，越高图层

import java.awt.Color;
import java.awt.HeadlessException;
import javax.swing.JFrame;
import javax.swing.JLayeredPane;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class JPanelParent extends JFrame {

    public JPanelParent() throws HeadlessException {
        JPanel nPanel = getNode(10, 10, 20, 20, Color.red, 1);
        JPanel nPanel2 = getNode(20, 20, 20, 20, Color.yellow, 2);
        JPanel nPanel3 = getNode(30, 30, 20, 20, Color.green, 3);
        JLayeredPane pane = new JLayeredPane();
        pane.add(nPanel, new Integer(1));
        pane.add(nPanel2, new Integer(2));
        pane.add(nPanel3, new Integer(3));

        setContentPane(pane);
        getContentPane().setBackground(Color.BLACK);
    }

    public JPanel getNode(int i, int i1, int j, int j1, Color color, int zOrder) {
        JPanel nodePanel = new JPanel();
        nodePanel.setBackground(color);
        nodePanel.setBounds(i, i1, j, j1);
        nodePanel.setOpaque(true);
        nodePanel.setLayout(null);
        return nodePanel;
    }

    public static void main(String argv[]) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                JPanelParent jpp = new JPanelParent();
                jpp.setVisible(true);
                jpp.setSize(300, 300);
                jpp.setBackground(Color.black);
            }
        });

    }
}

---

旁注

• 应该从Event Dispatch Thread运行Swing程序（就像我在上面的例子中所做的那样）。请点击Initial Threads
了解更多信息

Answer 2

如果您了解自己的问题，那么首先在将JPanels添加到父框架之前，您需要告诉parent frame将component添加到特定坐标中，并且可以完成通过为父框架设置Layout为空。

在构造函数的第一行添加此行。

setLayout(null);