public static void main(String[] args) {
        System.out.println(toBin(6));
        System.out.println(toHex(0));
        System.out.println(toOct(8));
    }
    
    public static String toBin(int num){
        return trans(num,1,1);
    }

    public static String toHex(int num){
        return trans(num,15,4);
    }

    public static String toOct(int num){
        return trans(num,7,3);
    }

    public static String trans(int num, int base, int offset){
        if (num ==0)
            return "0";
        char[] chs = {'0','1','2','3','4','5','6','7','8','9','A','B','C','B','E','F'};
        char[] arr = new char[32];
        int pos=arr.length;
        while (num!=0){
            int temp = num & base;
            arr[--pos]=chs[temp];
            num = num >>> offset;
        }
        StringBuffer stringBuffer = new StringBuffer();
        for (int i = pos; i < arr.length; i++) {
            stringBuffer.append(arr[i]);
        }
        return stringBuffer.toString();
    }