Collections-sort

import java.util.ArrayList;

import java.util.Collections;

import java.util.List;

/*

* 1.Collections.sort(list);只能对List排序，注意：list中的

* 元素类型必须具备可比较性(继承Comparable)

2.Collections.sort(list,new StrLenComparator());//指定比较器升序

*/

public class CollectionsTest {

public static void main(String[] args) {

sortDemo();

}

public static void sortDemo(){

List<String> list=new ArrayList<String>();

list.add("aasd");

list.add("aaa");

list.add("aaa");

list.add("dd");

list.add("ss");

list.add("gg");

System.out.println(list.toString());

Collections.sort(list);//默认升序

System.out.println(list.toString());

Collections.sort(list,new StrLenComparator());//指定比较器升序

System.out.println(list.toString());

}

}

//**************************************************************

import java.util.Comparator;

public class StrLenComparator implements Comparator<String>{

@Override

public int compare(String s1, String s2) {

// TODO Auto-generated method stub

if(s1.length()>s2.length()){

return 1;

}

if(s1.length()<s2.length()){

return -1;

}

return s1.compareTo(s2);

}

}