java 进制转化

     public static void toBinary(int num){
         trans(num,1,1);
     }
     public static void toHex(int num){
         trans(num,15,4);
     }
     public static void toOctal(int num){
         trans(num,7,3);
     }
     public static void trans(int num,int base,int offset){
         if(num==0){
             System.out.println('0');
             return;
         }
         char[] chs={'0','1','2','3',
                     '4','5','6','7',
                     '8','9','A','B',
                     'C','D','E','F'};
         char[] ch = new char[32];
         int pos=ch.length;
         while(num!=0){

             int temp = num & base;
             ch[--pos] = chs[temp];
             num = num >>> offset;
         }
         //System.out.println("pos="+pos);
         for(int x=pos;x<ch.length;x++){
             System.out.print(ch[x]);
         }
         System.out.println();
     }