Collections工具类

import java.util.*;

public class file {

    public static void main(String[] args) {
        stringReader();
    }

    private static void stringReader() {
        List list = new ArrayList();
        list.add("1");
        list.add("2");
        list.add("3");
        Collections.sort(list);
//        Collections.sort(list,Collections.reverseOrder());
        System.out.println(list);
    }
}