把数组排成最小的数

import java.util.*;

public class Solution {
    public String PrintMinNumber(int [] numbers) {
        if(numbers == null || numbers.length <= 0)
            return new String();
        
        Integer[] nums = new Integer[numbers.length];
        
        for(int i=0; i<numbers.length; i++) {
            nums[i] = new Integer(numbers[i]);
        }
        
        
        Arrays.sort(nums, new Comparator<Integer>() {
            @Override
            public int compare(Integer o1, Integer o2) {

                int val1 = Integer.parseInt(String.valueOf(o1) + String.valueOf(o2));
                int val2 = Integer.parseInt(String.valueOf(o2) + String.valueOf(o1));

                return val1 > val2 ? 1 : -1;
            }
        });
        
        StringBuilder ret = new StringBuilder();
        
        for(int i=0; i<nums.length; i++) {
            ret.append(nums[i]);
        }
        
    return ret.toString();
    }
}