yanzhengma.java

IO流的项目好

package myQQ;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.Random;


class YanZhengMa extends JPanel
{
	private	String []s ={"1","2","3","4","5","6","7","8","9",
	"A","B","C","D","E","F","G","H","J","K","L","M",
	"N","P","Q","R","S","T","U","V","W","X","Y","Z",
	"a","b","c","d","e","f","g","h","i","j","k","m",
	"n","p","q","r","s","t","u","v","w","x","y","z"};
	
	String s1;
	public YanZhengMa()
	{
		s1 = rand();
		System.out.println (s1);
	}
	
	public void paintComponent(Graphics g)
	{
		super.paintComponent(g);
		g.setFont(new Font("隶书",Font.BOLD+Font.ITALIC,26));
		g.setColor(Color.red);
		g.drawString(s1,20,20);
	}
	private String rand()
	{
		int m1,m2,m3,m4;
		Random r1 = new Random();
		m1 = r1.nextInt(s.length);
		while(true)
		{
			m2 = r1.nextInt(s.length);
			if(m1!=m2)
			break;
		}
		while(true)
		{
			m3 = r1.nextInt(s.length);
			if(m3!=m1&&m3!=m2)
			break;
		}
		while(true)
		{
			m4 = r1.nextInt(s.length);
			if(m4!=m1&&m4!=m2&&m4!=m3)
			break;
		}
		String sm = s[m1]+s[m2]+s[m3]+s[m4];
		return sm; 
	}
	public void again()
	{
		s1 = rand();
		repaint();
	}
}