17-集合框架-25-常用对象API(集合框架-TreeSet集合练习-字符串长度排序)

package cn.itcast.comparator;

import java.util.Comparator;

public class ComparatorByLength implements Comparator {

public int compare(Object o1, Object o2) {

String s1 = (String)o1;
String s2 = (String)o2;

int temp = s1.length() - s2.length();

return temp==0?s1.compareTo(s2):temp;//这里的compareTo是String类自己的方法

}

}

===========================================分割线====================================

package cn.itcast.treeset.test;

import java.util.Iterator;

import java.util.TreeSet;

import cn.itcast.comparator.ComparatorByLength;

public class TreeSetTest {

public static void main(String[] args) {

/*

* 需求：对字符串长度进行排序

*/

TreeSet ts = new TreeSet(new ComparatorByLength());

ts.add("aaaaa");

ts.add("zz");

ts.add("nbaq");

ts.add("cba");

ts.add("abc");

Iterator it = ts.iterator();

while(it.hasNext())

{

System.out.println(it.next());

}

}

}