我将如何在Java swing中进行此布局？

Question

I have a very specific layout in mind that I have been trying to accomplish for some time with no success. The layout I am trying to create is just to put a single JPanel, of a fixed height positioned in the vertical center of the other panel. Horizontally, it should stretch to fit the bounds of the other.

Again, the needs are for it to be:

1. Two JPanels, one placed inside the other
2. The inner panel should have a static height
3. The inner panel should be vertically centered
4. The inner panel should horizontally stretch to meet the sides of the outer panel.

The following is a picture of an example of this:

Per several people's requests for me to post my code which doesn't work:

JPanel MainPanel = new JPanel();
frmPhoneClicker.getContentPane().add(MainPanel);
MainPanel.setLayout(new MigLayout("", "[984px]", "[165px]"));


Panel subPanel = new JPanel();
subPanel.setLayout(new FlowLayout(FlowLayout.CENTER, 5, 5));
MainPanel.add(subPanel, "cell 0 0 1 1,growx,aligny center");

Answer 1

You definitely need to learn more about Layouts in your case GridBagLayout would be helpful. But here you go:

// your Panels
JPanel mainPanel = new JPanel();
JPanel subPanel = new JPanel();
mainPanel.setLayout(new GridBagLayout()); // use GridBagLayout with mainPanel
subPanel.setPreferredSize(new Dimension (0,165)); // use a preferred height for the subPanel
GridBagConstraints c = new GridBagConstraints(); // your gridBagLayout Constraints
c.fill = GridBagConstraints.HORIZONTAL; // stretch subPanel horizontal
c.weightx = 1.0; // with 100% of screen
mainPanel.add(subPanel,c); // add sub to mainPanel with the constraints

Answer 2

A complete working example with colors to follow your scheme:

import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Toolkit;
import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JPanel;


public class testPanel extends JFrame{

    public testPanel() {
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        int screenHeight = screenSize.height;
        int screenWidth = screenSize.width;
        this.setSize(screenWidth / 2, screenHeight * 2 / 3);

        this.setLocationRelativeTo(null);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        this.setResizable(true);
        this.setAlwaysOnTop(false);
        this.setUndecorated(false);

        JPanel outerPanel = new JPanel(new GridBagLayout());
        outerPanel.setBorder(BorderFactory.createLineBorder(Color.RED));
        JPanel innerPanel = new JPanel();
        innerPanel.setBorder(BorderFactory.createLineBorder(Color.BLUE));
        innerPanel.setPreferredSize(new Dimension (0,300));

        GridBagConstraints c = new GridBagConstraints();
        c.fill = GridBagConstraints.HORIZONTAL;
        c.weightx = 1;//Size
        outerPanel.add(innerPanel, c);

        this.add(outerPanel);
        this.setVisible(true);
    }

}

Please note that if the containing window size goes below the size of the innerPanel , then the fixed height will not apply anymore.