Java_随机生成4位验证码

import java.util.*;//导入java.util包下的类

public class JavaDemo10
{
	public static void main(String args[])
	{
		String str = "0,1,2,3,4,5,6,7,8,9,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z";
		String str2[] = str.split(",");//将字符串以,分割
		int sum = 0;//计数器
		for (int i=0; i