按字符串长度排序——TreeSet练习

import java.util.*;
/*
练习：按照字符串长度排序
*/
class TreeSetDemo
{
public static void main(String [] args)
{
TreeSet ts=new TreeSet(new Mycompare());

ts.add("acdf");
ts.add("ab");
ts.add("bd");
ts.add("c");

Iterator it= ts.iterator();

while(it.hasNext())
{
System.out.println(it.next());
}

}
}
class Mycompare implements Comparator<String >
{
public int compare(String s1,String s2)
{
int a=new Integer(s1.length()).compareTo(new Integer(s2.length()));
if(a==0)
return s1.compareTo(s2);
return a;
}
}