java 随机函数初试,输出一个32位的随机数

import java.util.Random;

class t1{
public static void main(String[] args)
{
         Random random1 = new Random();
         char a;
         String b="";
         for(int j=0;j<100;j++)
         {
          for(int i=0;i<10000;i++)
          {
           a=(char)Math.abs(random1.nextInt()%122);
           if( (a>=\'0\' && a<=\'9\') || (a>=\'A\' && a<=\'Z\') || ( a>=\'a\' && a<=\'z\'))
           {
           // System.out.println(a);
            b=b+a;
           }
           if(b.length()==32)
           {
            break;
           }
          
          }
          System.out.println(b);
          b="";
         }
       
}
        
        
  
   
}