把数组排成最小的数

题目描述
输入一个正整数数组，把数组里所有数字拼接起来排成一个数，打印能拼接出的所有数字中最小的一个。例如输入数组{3，32，321}，则打印出这三个数字能排成的最小数字为321323。

package alex.jzoffer;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Scanner;

public class PrintMinNumberOfArray {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner scanner = new Scanner(System.in);
        System.out.println("please input the size of array:");
        int n = scanner.nextInt();
        System.out.println("please input an array:");
        int a[] = new int[n];
        for(int i = 0;i < n;i++){
            a[i] = scanner.nextInt();
        }
        System.out.println("minNumberOfArray is:" + PrintMinNumber(a));
    }

    public static String PrintMinNumber(int[] numbers) {
        int len = numbers.length;
        if (len == 0) {
            return "";
        }
        ArrayList<Integer> list = new ArrayList<Integer>();
        for (int i = 0; i < len; i++) {
            list.add(numbers[i]);
        }
        Collections.sort(list, new Comparator<Integer>() {
            @Override
            public int compare(Integer o1, Integer o2) {
                String str1 = o1 + "" + o2;
                String str2 = o2 + "" + o1;
                return str1.compareTo(str2);
            }
        });
        String s = "";
        for(int i=0;i<len;i++){
            s += list.get(i);
        }
        return s;
    }

}