Java GridBagLayout：如何设置固定列宽？
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GridBagLayout: How to set fixed column width?
提问by Marie
I've been trying to set fixed column width in the following code for ages...The thing is that when I add a label to the panel on the left, then the width is incremented automatically...and i Would like the column width to be fixed...
我一直在尝试在以下代码中设置固定列宽多年...问题是当我向左侧面板添加标签时，宽度会自动增加...我想要列宽度固定...
Could anyone help me please??
有人可以帮我吗？？
This is the code:
这是代码：
import java.awt.AWTException;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Cursor;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Image;
import java.awt.Panel;
import java.awt.Point;
import java.awt.Robot;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Timer;
import java.util.TimerTask;
import javax.sound.sampled.AudioFileFormat;
import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioInputStream;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.DataLine;
import javax.sound.sampled.LineUnavailableException;
import javax.sound.sampled.TargetDataLine;
import javax.swing.BorderFactory;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.border.Border;
import java.io.IOException;
public class CurrentItem extends JPanel{
private static JFrame currentScreen;
public CurrentItem(JFrame p) {
GridBagConstraints c = new GridBagConstraints();
//Borramos todo lo que haya en la pantalla
this.removeAll();
this.revalidate();
currentScreen = p;
this.setBackground(Color.LIGHT_GRAY);
this.setLayout(new GridBagLayout());
currentScreen.add(this);
// --->
Panel leftPanel = new Panel();
leftPanel.setBackground(Color.BLACK);
c.weightx = 1.5;
c.weighty = 1;
//c.fill = GridBagConstraints.BOTH;
this.add(leftPanel, c);
// <---
// --->
Panel secondPanel = new Panel();
secondPanel.setBackground(Color.green);
c.weightx = 0.25;
c.weighty = 1;
c.fill = GridBagConstraints.BOTH;
this.add(secondPanel, c);
// <---
// --->
Panel rightPanel = new Panel();
rightPanel.setBackground(Color.CYAN);
c.weightx = 1.5;
c.weighty = 1;
c.fill = GridBagConstraints.BOTH;
this.add(rightPanel, c);
// <---
currentScreen.setVisible(true);
this.requestFocusInWindow();
}
}
回答by Braj
GridBagLayoutplaces components in rectangles (cells) in a grid, and then uses the components' preferred sizesto determine how big the cells should be.
GridBagLayout将组件放在网格中的矩形（单元格）中，然后使用组件的首选大小来确定单元格应该有多大。
Weights are used to determine how to distribute space among columns (weightx) and among rows (weighty); this is important for specifying resizing behavior.
权重用于确定如何在列 ( weightx) 和行 ( weighty)之间分配空间；这对于指定调整大小行为很重要。
Generally weights are specified with 0.0 and 1.0 as the extremes: the numbers in between are used as necessary.
通常权重指定为 0.0 和 1.0 作为极端值：根据需要使用介于两者之间的数字。
Read more How to Use GridBagLayout
Sample code: (below code set fixed width column with 100% vertical size.)
示例代码：（下面的代码设置了 100% 垂直大小的固定宽度列。）
Panel leftPanel = new Panel() {
@Override
public Dimension getPreferredSize() {
return new Dimension(..., ...);
}
};
Remove weightxfor first column and override getPreferredSize()method.
删除weightx第一列并覆盖getPreferredSize()方法。
leftPanel.setBackground(Color.BLACK);
c.weighty = 1;
c.fill = GridBagConstraints.VERTICAL;
this.add(leftPanel, c);
回答by splungebob
If you know ahead of time the labels that you'll be adding, and how wide each one is:
如果您提前知道要添加的标签以及每个标签的宽度：
You can call
label.getPreferredSize().widthon each label to determine the width of the largest label.Then, add an invisible component (
Box.createHorizontalStrut(width)) to the column to force it to be that wide at all times.Then, when you add all of your labels, the width of that column of the panel will not change.
您可以调用
label.getPreferredSize().width每个标签来确定最大标签的宽度。然后，
Box.createHorizontalStrut(width)向该列添加一个不可见组件 ( ) 以使其始终保持那么宽。然后，当您添加所有标签时，面板该列的宽度不会改变。
