Collections.sort排序的问题，请教

import java.util.Comparator;
import java.util.*;
public class SsvlistInfoCompare implements Comparator<String[]> {


    /**
     *
     */
    public int compare(String[] a, String[] b) {
        //如果a 大于b 返回 整数 1 、相等返回 0 、小于返回 -1
        //按升序排列 如果要设置成降序写成b.compareTo(a);
        int flag = a[0].compareTo(b[0]);
        return flag;
    }

    public static void main(String[] strs) {
        List<String[]> list = new ArrayList<String[]>();
        for(int i = 0 ; i < 20 ; i++){
            String[] ary = new String[1];
            ary[0] = String.valueOf(i);
            list.add(ary);

        }

        SsvlistInfoCompare s = new SsvlistInfoCompare();
        //实现顺序或者倒序排列
        Collections.sort(list, s);

        for (int i = 0; i < list.size(); i++) {
            String[] ary = list.get(i);
            System.out.println(ary[0]);

        }
    }
}

急 谢谢
[解决办法]

import java.util.Comparator;
import java.util.*;
public class SsvlistInfoCompare implements Comparator<String[]> {
 
 
    /**
     *
     */
    public int compare(String[] a, String[] b) {
        //如果a 大于b 返回 整数 1 、相等返回 0 、小于返回 -1
        //按升序排列 如果要设置成降序写成b.compareTo(a);
        int flag = Integer.parseInt(a[0]) - Integer.parseInt(b[0]);
        return flag;
    }
 
    public static void main(String[] strs) {
        List<String[]> list = new ArrayList<String[]>();
        for(int i = 0 ; i < 20 ; i++){
            String[] ary = new String[1];
            ary[0] = String.valueOf(i);
            list.add(ary);
 
        }
 
        SsvlistInfoCompare s = new SsvlistInfoCompare();
        //实现顺序或者倒序排列
        Collections.sort(list, s);
 
        for (int i = 0; i < list.size(); i++) {
            String[] ary = list.get(i);
            System.out.println(ary[0]);
 
        }
    }
}