GUI GirdBagLayout布局 显示

Question

第二个JButton和第三个JButton重叠  
代码如下：
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;public class test2  extends JApplet //implements ActionListener,ItemListener
{
JButton bt1=new JButton("K"),
bt2=new JButton("安全"),
bt3=new JButton("设置");

JFrame jf=null; public test2()
{
jf=new JFrame("QQ用户登录");
Container cp=jf.getContentPane();

GridBagLayout grid=new GridBagLayout();
GridBagConstraints c=null;
int gridx,gridy,gridwidth,gridheight,anchor,fill,ipadx,ipady;
double weightx,weighty;
Insets inset;

cp.setLayout(grid);

gridx=0;
gridy=0;
gridwidth=4;
gridheight=1;
weightx=0;
weighty=0;
anchor=GridBagConstraints.NORTH;
fill=GridBagConstraints.NONE;
inset = new Insets(0,0,0,0); 
ipadx=10;
ipady=10;

c = new GridBagConstraints(gridx,gridy,gridwidth,gridheight,
            weightx,weighty,anchor,fill,inset,ipadx,ipady);
grid.setConstraints(bt3, c);
cp.add(bt3);

gridy=1;
gridheight=2;
c = new GridBagConstraints(gridx,gridy,gridwidth,gridheight,
            weightx,weighty,anchor,fill,inset,ipadx,ipady);
grid.setConstraints(bt1, c);
cp.add(bt1);

gridy=2;
gridheight=1;
c = new GridBagConstraints(gridx,gridy,gridwidth,gridheight,
            weightx,weighty,anchor,fill,inset,ipadx,ipady);
grid.setConstraints(bt2, c);
cp.add(bt2);

jf.setBounds(300,400,400,300);
jf.setVisible(true);}public static void main(String[]args)
{
new test2(); }}

Answer 1

个人认为最好的布局就是没有布局，JPanel都设为setLayout（null）
在通过每个component的setBounds(new Rectangle(int x, int y, int width, int height))方法来设置其位置、大小。非常的好用
不过最好是要有一个Visual Editor配合使用

Answer 2

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;public class test2 extends JApplet // implements ActionListener,ItemListener
{
    JButton bt1 = new JButton("K"), bt2 = new JButton("security"), bt3 = new JButton("set");    JFrame jf = null;    public test2() {
        jf = new JFrame("login");
        JPanel panel = new JPanel();
        GridBagLayout grid = new GridBagLayout();
        GridBagConstraints c = null;
        int gridx, gridy, gridwidth, gridheight, anchor, fill, ipadx, ipady;
        double weightx, weighty;
        Insets inset;        panel.setLayout(grid);        gridx = 0;
        gridy = 0;
        gridwidth = 4;
        gridheight = 1;
        weightx = 0;
        weighty = 0;
        anchor = GridBagConstraints.CENTER;
        fill = GridBagConstraints.NONE;
        inset = new Insets(0, 0, 0, 0);
        ipadx = 10;
        ipady = 10;        c = new GridBagConstraints(
            gridx,
            gridy,
            gridwidth,
            gridheight,
            weightx,
            weighty,
            anchor,
            fill,
            inset,
            ipadx,
            ipady);
        grid.setConstraints(bt3, c);
        panel.add(bt3);        gridx = 1;
        gridy = 1;
        gridheight = 2;
        c = new GridBagConstraints(
            gridx,
            gridy,
            gridwidth,
            gridheight,
            weightx,
            weighty,
            anchor,
            fill,
            inset,
            ipadx,
            ipady);
        grid.setConstraints(bt1, c);
        panel.add(bt1);        gridy = 3;
        gridheight = 1;
        c = new GridBagConstraints(
            gridx,
            gridy,
            gridwidth,
            gridheight,
            weightx,
            weighty,
            anchor,
            fill,
            inset,
            ipadx,
            ipady);
        grid.setConstraints(bt2, c);
        panel.add(bt2);
        jf.setContentPane(panel);
        jf.setBounds(300, 400, 400, 300);
        jf.setVisible(true);
        jf.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    }    public static void main(String[] args) {
        new test2();    }}

Answer 3

SAGEM_M() ： 可能这gridwidth个设的太大了
和gridwidth没有关系，我试着将gridheight改小后，就可以显示出来，但是问题是我想让bt1占的高度是bt3、bt2的两倍亚；zwgs1985(流氓狗) ：为什么要使用面板？即便是用了，bt1组件的高度也不是bt2的两倍；如果将bt1组件的gridheight改为大于2的数，则bt1和bt2又会重叠；希望大家能说明原因，谢谢

Answer 4

import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;import javax.swing.JApplet;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.WindowConstants;public class test2 extends JApplet // implements ActionListener,ItemListener
{
    JButton bt1 = new JButton("K"), bt2 = new JButton("security"), bt3 = new JButton("set");    JFrame jf = null;    public test2() {
        jf = new JFrame("login");
        JPanel panel = new JPanel();
        GridBagLayout grid = new GridBagLayout();
        GridBagConstraints c = new GridBagConstraints();
        // int gridx, gridy, gridwidth, gridheight, anchor, fill, ipadx, ipady;
        // double weightx, weighty;
        // Insets inset;        panel.setLayout(grid);        c.gridx = 0;
        c.gridy = 0;
        c.weightx = 1.0;
        c.weighty = 1.0;
        // gridwidth = 4;
        // gridheight = 1;
        // weightx = 0;
        // weighty = 0;
        // anchor = GridBagConstraints.CENTER;
        c.fill = GridBagConstraints.VERTICAL;
        // inset = new Insets(0, 0, 0, 0);
        // ipadx = 10;
        // ipady = 10;        // c = new GridBagConstraints(
        // gridx,
        // gridy,
        // gridwidth,
        // gridheight,
        // weightx,
        // weighty,
        // anchor,
        // fill,
        // inset,
        // ipadx,
        // ipady);
        grid.setConstraints(bt3, c);
        panel.add(bt3);        c.weighty = 2.0;
        c.gridy = 1;
        c.gridheight = 2;
        // c = new GridBagConstraints(
        // gridx,
        // gridy,
        // gridwidth,
        // gridheight,
        // weightx,
        // weighty,
        // anchor,
        // fill,
        // inset,
        // ipadx,
        // ipady);
        grid.setConstraints(bt1, c);
        panel.add(bt1);        c.weighty = 1.0;
        c.gridy = 3;
        c.gridheight = 1;
        // c = new GridBagConstraints(
        // gridx,
        // gridy,
        // gridwidth,
        // gridheight,
        // weightx,
        // weighty,
        // anchor,
        // fill,
        // inset,
        // ipadx,
        // ipady);
        grid.setConstraints(bt2, c);
        panel.add(bt2);
        jf.setContentPane(panel);
        jf.setBounds(300, 400, 400, 300);
        jf.setVisible(true);
        jf.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    }    public static void main(String[] args) {
        new test2();
    }}

Answer 5

c.fill = GridBagConstraints.VERTICAL;
让控件能够在纵向上填满整个空间，
如果不设置这个的话，可能控件没有办法调整高度
只是可能，我也没深看底层的实现，自己看看吧

Answer 6

其实你把cp.add(bt1);后面的gridy=2改成3就可以了