测试Set的打印输出

/*
*此测试程序的目的是检测Set的toString()方法是否是由叠代器来遍历集合的
*顺便检测低层存储顺序（Set提供的toString()方法应该是反映的底层结构）
*/

//PrintSet.java

package com.msn.spaces.bryantd001;
import java.util.*;

class MyHashSet extends HashSet{
      public String toString(){
            String result = "{";
            Iterator it = iterator();
            while (it.hasNext()){
                  result += it.next().toString() + ' ';
            }
            result += "}";
            return result;
      }
}

class  MyTreeSet extends TreeSet{
      public String toString(){
            String result = "{";
            Iterator it = iterator();
            while (it.hasNext()){
                  result += it.next().toString() + ' ';
            }
            result += "}";
            return result;
      }
}

class MyLinkedHashSet extends LinkedHashSet{
      public String toString(){
            String result = "{";
            Iterator it = iterator();
            while (it.hasNext()){
                  result += it.next().toString() + ' ';
            }
            result += "}";
            return result;
      }
}

public class PrintSet{
      static void fill(Set set){
            for (int i = 0; i < 5; i++){
                  set.add(new Integer(i));
            }
      }
     

      public static void main(String[] args){
            HashSet hs = new HashSet();
            TreeSet ts = new TreeSet();
            LinkedHashSet lhs = new LinkedHashSet();
            fill(hs);
            fill(ts);
            fill(lhs);

            System.out.println("Show the order of the Sets by the default toStrintg() way.");
            System.out.println(hs);
            System.out.println(ts);
            System.out.println(lhs);
            System.out.println();

           MyHashSet mhs = new MyHashSet();
           MyTreeSet mts = new MyTreeSet();
           MyLinkedHashSet mlhs = new MyLinkedHashSet();
           fill(mhs);
           fill(mts);
           fill(mlhs);
           System.out.println("Show the order of the Customized Sets by my toString() way.");
           System.out.println(mhs);
           System.out.println(mts);
           System.out.println(mlhs);  
     }
}