Question

JAVA BorderLayout布局

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class PanelRunner2 {
public static void main(String[] args)
{
JFrame frame = new JFrame("Color Panels");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(1200, 1000);
JPanel panel = new JPanel();
panel.setPreferredSize(new Dimension(1200, 1000));
JPanel subpanel1 = new JPanel();
subpanel1.setBackground(Color.RED);
subpanel1.setPreferredSize(new Dimension(200, 200));
panel. add(subpanel1, BorderLayout.NORTH);
JPanel subpanel2 = new JPanel();
subpanel2.setBackground(Color.WHITE);
subpanel2.setPreferredSize(new Dimension(200, 200));
panel.add(subpanel2,BorderLayout.WEST);
JPanel subpanel3 = new JPanel();
subpanel3.setBackground(Color.BLUE);
subpanel3.setPreferredSize(new Dimension(200, 200));
panel.add(subpanel3,BorderLayout.AFTER_LAST_LINE);
JPanel subpanel4 = new JPanel();
subpanel4.setBackground(Color.GREEN);
subpanel4.setPreferredSize(new Dimension(200, 200));
panel.add(subpanel4,BorderLayout.AFTER_LAST_LINE);
JPanel subpanel5 = new JPanel();
subpanel5.setBackground(Color.YELLOW);
subpanel5.setPreferredSize(new Dimension(200, 200));
panel.add(subpanel5,BorderLayout.EAST);
JPanel subpanel6 = new JPanel();
subpanel6.setBackground(Color.ORANGE);
subpanel6.setPreferredSize(new Dimension(200,200));
panel.add(subpanel6, BorderLayout.SOUTH);
frame.add(panel);
frame.setVisible(true);
}
}
要求布局如下，
You will need to create another subpanel to hold the blue and green panels. Try running the program and making the framenarrower. What happens the panels in thecenter? Why? Fix the problem by using a GridLayout manager forthe center panel.
GridLayout不知道怎么用，求大神修改。

Answer 1

package image;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class PanelRunner extends JFrame
{
	private static final long serialVersionUID = 1L;

	private static void initPanels ( JFrame pr )
	{
		for ( int i = 0; i < 5; i++ )
		{
			JPanel panel = new JPanel ();
			switch (i)
			{
				case 0:
					panel.setBackground (Color.RED);
					panel.setPreferredSize (new Dimension (200, 100));
					pr.add (panel, BorderLayout.NORTH);
					break;
				case 1:
					panel.setBackground (Color.YELLOW);
					panel.setPreferredSize (new Dimension (200, 300));
					pr.add (panel, BorderLayout.EAST);
					break;
				case 2:
					panel.setBackground (Color.ORANGE);
					panel.setPreferredSize (new Dimension (200, 100));
					pr.add (panel, BorderLayout.SOUTH);
					break;
				case 3:
					panel.setBackground (Color.WHITE);
					panel.setPreferredSize (new Dimension (200, 300));
					pr.add (panel, BorderLayout.WEST);
					break;
				case 4:
					pr.add (panel, BorderLayout.CENTER);
					panel.setPreferredSize (new Dimension (200, 100));
					panel.setLayout (new GridLayout (1, 2));
					for ( int j = 0; j < 2; j++ )
					{
						JPanel subPanel = new JPanel ();
						subPanel.setPreferredSize (new Dimension (200, 100));
						Color color = j == 0 ? Color.BLUE : Color.GREEN;
						subPanel.setBackground (color);
						panel.add (subPanel);
					}
					break;
				default:
					break;
			}
		}
	}

	private static void initFrame ( JFrame pr )
	{
		pr.setLayout (new BorderLayout ());
		pr.setSize (600, 300);
		pr.setLocationRelativeTo (null);
		pr.setResizable (false);
		pr.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
	}

	public static void main ( String[] args )
	{
		SwingUtilities.invokeLater (new Runnable ()
		{
			@Override
			public void run ()
			{
				PanelRunner pr = new PanelRunner ();
				initFrame (pr);
				initPanels (pr);
				pr.setVisible (true);
			}
		});
	}
}

Answer 2

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class PanelRunner2 {
public static void main(String[] args)
{
JFrame frame = new JFrame("Color Panels");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(1200, 1000);
JPanel panel = new JPanel();
panel.setLayout(new BorderLayout());
panel.setPreferredSize(new Dimension(1200, 1000));
JPanel subpanel1 = new JPanel();
subpanel1.setBackground(Color.RED);
subpanel1.setPreferredSize(new Dimension(200, 200));
panel.add(subpanel1, BorderLayout.NORTH);
JPanel panelCenter = new JPanel();
panelCenter.setLayout(new GridLayout(1,4));
JPanel subpanel2 = new JPanel();
subpanel2.setBackground(Color.WHITE);
subpanel2.setPreferredSize(new Dimension(200, 200));
panelCenter.add(subpanel2, BorderLayout.WEST);

JPanel subpanel3 = new JPanel();
subpanel3.setBackground(Color.BLUE);

subpanel3.setPreferredSize(new Dimension(200, 200));

panelCenter.add(subpanel3);
JPanel subpanel4 = new JPanel();
subpanel4.setBackground(Color.GREEN);
subpanel4.setPreferredSize(new Dimension(200, 200));
panelCenter.add(subpanel4);
JPanel subpanel5 = new JPanel();
subpanel5.setBackground(Color.YELLOW);
subpanel5.setPreferredSize(new Dimension(200, 200));
panelCenter.add(subpanel5);
panel.add(panelCenter,BorderLayout.CENTER);

JPanel subpanel6 = new JPanel();
subpanel6.setBackground(Color.ORANGE);
subpanel6.setPreferredSize(new Dimension(200, 200));
panel.add(subpanel6, BorderLayout.SOUTH);
frame.add(panel);
frame.setVisible(true);
}
}

追问

中间两个只能显示一个，要求使用GridLayout修改。

追答

额！