关于布局的问题

Question

我写了一个程序，可是不管我怎么调，中间的文本区还是那么小，高手可不可以帮我看下
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;public class FontDemo
{
public static void main(String[] args)
{
FontDemoFrame frame=new FontDemoFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.show();
}
}class FontDemoFrame extends JFrame
{
public FontDemoFrame()
{
setTitle("FontDemo");
setSize(DEFAULT_WIDTH,DEFAULT_HEIGHT);

Container contentPane=getContentPane();
GridBagLayout layout=new GridBagLayout();
contentPane.setLayout(layout);

ActionListener listener1=new FontAction();
ActionListener listener2=new AreaAction();

JLabel facelabel=new JLabel("Face:");

face=new JComboBox(new String[]{
"Serif","SansSerif","Monospaced","Dialog","DialogInput"
});
face.addActionListener(listener1);

JLabel sizelabel=new JLabel("Size:");

size=new JComboBox(new String[]{
"8","10","12","15","18","24","36","48"
});
size.addActionListener(listener1);

bold=new JCheckBox("Bold");
bold.addActionListener(listener1);

italic=new JCheckBox("Itatic");
italic.addActionListener(listener1);

sample=new JTextArea();
sample.setText("The quick brown fox jumps over the lazy dog");
sample.setEditable(false);
sample.setLineWrap(true);
sample.setBorder(BorderFactory.createEtchedBorder());

JButton replace=new JButton("Replace");
replace.addActionListener(listener2);

from=new JTextField();
JLabel with=new JLabel("With");
to=new JTextField();

GridBagConstraints constraints=new GridBagConstraints();

constraints.fill=GridBagConstraints.NONE;
constraints.anchor=GridBagConstraints.CENTER;
constraints.weightx=0;
constraints.weighty=0;

add(facelabel,constraints,0,0,1,1);
add(sizelabel,constraints,0,1,1,1);

constraints.fill=GridBagConstraints.HORIZONTAL;
constraints.anchor=GridBagConstraints.CENTER;
    constraints.weightx=100;

add(face,constraints,1,0,2,1);
add(size,constraints,1,1,2,1);

constraints.fill=GridBagConstraints.NONE;
    constraints.weighty=100;

add(bold,constraints,3,0,1,1);
add(italic,constraints,3,1,1,1);

constraints.fill=GridBagConstraints.BOTH;
constraints.anchor=GridBagConstraints.CENTER;
add(sample,constraints,0,2,4,5);

constraints.fill=GridBagConstraints.NONE;
constraints.anchor=GridBagConstraints.CENTER;

add(replace,constraints,0,7,1,1);


constraints.fill=GridBagConstraints.HORIZONTAL;
constraints.anchor=GridBagConstraints.CENTER;
constraints.weightx=100;

add(from,constraints,1,7,1,1);

constraints.fill=GridBagConstraints.NONE;
constraints.anchor=GridBagConstraints.CENTER;
add(with,constraints,2,7,1,1);

constraints.fill=GridBagConstraints.HORIZONTAL;
constraints.anchor=GridBagConstraints.CENTER;
constraints.weightx=100;

add(to,constraints,3,7,1,1);
}

public void add(Component c,GridBagConstraints constraints,int x,int y,int w,int h)
{
constraints.gridx=x;
constraints.gridy=y;
constraints.gridwidth=w;
constraints.gridheight=h;
getContentPane().add(c,constraints);
}

public static final int DEFAULT_WIDTH=300;
public static final int DEFAULT_HEIGHT=400;

private JComboBox face;
private JComboBox size;
private JCheckBox bold;
private JCheckBox italic;
private JTextArea sample;
private JTextField from;
private JTextField to;

private class FontAction implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
String fontFace=(String)face.getSelectedItem();
int fontsize=Integer.parseInt((String)size.getSelectedItem());
int mode=0;
if(bold.isSelected())
mode+=Font.BOLD;
if(italic.isSelected())
mode+=Font.ITALIC;
Font font=new Font(fontFace,mode,fontsize);
sample.setFont(font);
sample.repaint();
}
}

private class AreaAction implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
String f=from.getText();
int n=sample.getText().indexOf(f);
if(n>=0&&f.length()>0)
sample.replaceRange(to.getText(),n,n+f.length());
}
}
}

Answer 1

你将所有的constraints.weightx=100;都注释掉,
只在文本域的布局限制中加上constraints.weighty=3;就可以了.
估计你对weightx和weighty误解了.

Answer 2

楼上所说的好象不行啊，请各位高手能帮我解释一下什么是weightx和weighty，我看了书，但还是不怎么理解

Answer 3

GridLayout可以理解为行列式布局,GridBagLayout就是不规则行列式布局
weightx指出该组件跨越几行,weighty指出跨越几列.

Answer 4

楼上所说的应该有错把gridwidth,gridheight才是该组件所跨越的行和列把

Answer 5

我一直在关注这个贴 因为这也是我不明白的问题 楼主这个程序的源码出自core javaI 我也是看了书之后和楼主有了同样混乱的感觉，这个程序我也改了好几遍，找不到特别清晰的规律
现在有几个参数要区分，下面是书上的原话：
gridx,guidy/////////////////单元格的起始行列，左上角从0，0开始
gridwidth,gridheight////////单元格的行数和列数
weightx,weighty/////////////单元格放大时的增量
关于gridwidth和weightx的说法与wulemale(wulemale)说的就有点出入了
这是怎么回事呀

Answer 6

前面我写错了,是gridwidth和gridheight分别表示组件跨越的行数和列数.weightx和weighty规定组件的显示占据首选尺寸外的多少额外空间.
在你这个例子中,我觉得用BorderLayout比较好,将文本域放到center,用嵌套Panel进行North的布局

Answer 7

楼上的意思我明白，但是我刚开始学GridBagLayout，我做这个例子只是想自己熟悉这个布局