问题描述

怎样使界面成为下面的样子，求好心人帮帮忙。。

源程序：import java.awt.*;
import java.awt.event.*;

import javax.swing.*;
public class RecJFrame extends JFrame implements ActionListenerComponentListener {
private JRadioButton colorsbutton[]; //单选按钮组
private RecNCanvas canvas; //自定义画布组件
public RecJFrame()
{
super(""图画—颜色""); //框架边布局
Dimension dim=getToolkit().getScreenSize(); //获得屏幕分辨率
this.setBounds(dim.width/4dim.height/4dim.width/2dim.height/2); //窗口居中
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
this.addComponentListener(this); //注册组件事件监听器

    JToolBar toolbar=new JToolBar();                   //创建工具栏，默认水平方向    this.getContentPane().add(toolbarNorth"");        //工具栏添加到框架内容窗格北部    JButton button_color = new JButton(""选择颜色"");    toolbar.add(button_color);    button_color.addActionListener(this);    String colors[]={""红""黄""蓝""};    ButtonGroup bgroup = new ButtonGroup();            //按钮组    colorsbutton = new JRadioButton[colors.length];    //单选按钮数组    for (int i=0; i<colorsbutton.length; i++)    {        colorsbutton[i]=new JRadioButton(colors[i]);   //单选按钮        colorsbutton[i].addActionListener(this);        bgroup.add(colorsbutton[i]);                    //单选按钮添加到按钮组        toolbar.add(colorsbutton[i]);                   //单选按钮添加到工具栏    }    canvas = new RecNCanvas();                //创建自定义画布组件    this.getContentPane().add(canvasCenter"");    this.setVisible(true); //创建自定义画布组件this.getBackground()Color.yellow}    public void actionPerformed(ActionEvent e)             //按钮动作事件处理方法    {       if(e.getActionCommand().equals(""红""))        {            canvas.setColor(Color.red);            }       if(e.getActionCommand().equals(""蓝""))            {                canvas.setColor(Color.blue);                }        if(e.getActionCommand().equals(""黄""))            {                canvas.setColor(Color.yellow);                }       if (e.getActionCommand().equals(""选择颜色""))        {            Color c=JColorChooser.showDialog(this选择颜色""Color.blue); //弹出JColorChooser颜色选择对话框，返回选中颜色            canvas.setColor(c);        }            canvas.repaint();//需要在这里加上repaint    }    public void componentHidden(ComponentEvent arg0) {}    public void componentMoved(ComponentEvent arg0) {}    public void componentResized(ComponentEvent arg0) {}    public void componentShown(ComponentEvent arg0) {}    public static void main(String arg[])    {        new RecJFrame();    }

}
class RecNCanvas extends Canvas
{
private Color color;
public void setColor(Color color)
{
this.color=color;
}
public void paint(Graphics g)
{
int x0=this.getWidth()/4;
int y0=this.getHeight()/4;
g.setColor(this.color);
g.drawRect(x0y0250100);
}
}

解决方案

加一段代码。搜索canvas = new RecNCanvas(); //创建自定义画布组件，在这前后增加内容

 JPanel jp = new JPanel(new FlowLayout(FlowLayout.RIGHT));    jp.setPreferredSize(new Dimension(150 50));    JPanel jp2 = new JPanel();    jp2.setPreferredSize(new Dimension(50 100));    jp2.setBorder(BorderFactory.createLineBorder(Color.blue));//设置面板边框颜    ButtonGroup bgroup2 = new ButtonGroup();            //按钮组    JRadioButton[] colorsbutton2 = new JRadioButton[colors.length];    //单选按钮数组    for (int i=0; i<colorsbutton2.length; i++)    {        colorsbutton2[i]=new JRadioButton(colors[i]);   //单选按钮        colorsbutton2[i].addActionListener(this);        bgroup2.add(colorsbutton[i]);                    //单选按钮添加到按钮组        jp2.add(colorsbutton2[i]);    }    jp.add(jp2);    canvas = new RecNCanvas();                //创建自定义画布组件    this.getContentPane().add(jpWest"");    this.getContentPane().add(canvasCenter"");