/*****************************************
展示JRadioButton與ButtonGroup，用在選顏色
*************************************************/
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
public class ui28 extends JFrame implements ActionListener,ItemListener 
{
    Container c;
    JButton bot0,bot1;
    Color pencolor[]=new Color[5];
    JRadioButton[] rb=new JRadioButton[5];
    ButtonGroup rg = new ButtonGroup();
    JLabel[] lab=new JLabel[5];
    int cpt=0;
    int clear_mode=1;//一開始先清除畫面
    int now_x=0,now_y=0;
    public ui28()
    {
        super("JRadioButton選顏色展示");
        int i;
        int x;
        c=getContentPane();
        pencolor[0]=Color.white;
        pencolor[1]=Color.green;
        pencolor[2]=Color.blue;
        pencolor[3]=Color.red;
        pencolor[4]=Color.yellow;
        c.setLayout(new FlowLayout(FlowLayout.CENTER));
        bot0=new JButton("結束");
        bot1=new JButton("清除");
        c.add(bot0);
        c.add(bot1);
        lab[0]=new JLabel("白色");
        lab[1]=new JLabel("綠色");
        lab[2]=new JLabel("藍色");
        lab[3]=new JLabel("紅色");
        lab[4]=new JLabel("黃色");
        for (i=0;i<5;i=i+1)
        {
            rb[i]=new JRadioButton();
            c.add(rb[i]);
            c.add(lab[i]);
            rg.add(rb[i]);
            rb[i].addItemListener(this);//設定顏色選擇
        }
        rb[0].setSelected(true);//先設定白色
        bot0.addActionListener(this);
        bot1.addActionListener(this);
        addMouseMotionListener(new checkmouse());//設定滑鼠
        setSize(350,500);
        setVisible(true);
    }
    public void paint(Graphics g)
    {
        if (clear_mode==1)   super.paint(g);
        g.setColor(pencolor[cpt]);
        g.drawLine(now_x,now_y,now_x,now_y);
    }
    /***按鈕事件的傾聽方法****/
    public void actionPerformed(ActionEvent e) //按鈕事件的處理方法
    { 
        if (e.getSource()==bot0)
        {
            System.exit(0);
        }
        else if (e.getSource()==bot1)
        {
            clear_mode=1;
        }//bot1
        repaint();
    }
    public void itemStateChanged(ItemEvent e)//item事件處理方法
    {
        int ii;
        for (ii=0;ii<5;ii=ii+1)
        {
            if (rb[ii].isSelected())
            cpt=ii;
        }
        repaint();    
    }
    /*****實作滑鼠移動事件處理物件 *******/
    class checkmouse extends MouseMotionAdapter
    {
        public void mouseDragged(MouseEvent e)
        { 
            now_x=e.getX();
            now_y=e.getY();
            clear_mode=0;//開始畫圖，不可以清掉舊資料
            repaint(); //重新顯示一次
        }	
    }//checkmouse 
    public static void main(String args[]) //程式起點
    {
        ui28 app=new ui28(); //畫圖
        //處理視窗關閉要求
        app.addWindowListener(
             new WindowAdapter()
             {
                public void windowClosing(WindowEvent e)
                {  System.exit(0);}
             });
    }
}