About next() of HashMap keySet

Note:
If you found all of the a4 values are the same as a1, please change the init value of h4 such as：
  static HashMap<String, String> h4 = new HashMap<String, String>(1);

package test;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map.Entry;

public class Testor {
  static Testor t = new Testor();
  class T1{
    String s;
    T1(String pS){
      s = pS;
    }
    @Override
    public int hashCode() {
      return (int)(Math.random()*1000);
    }
    @Override
    public String toString() {
      return s;
    }
  }
  class T2{
    String s;
    T2(String pS){
      s = pS;
    }
    @Override
    public int hashCode() {
      return s.hashCode();
    }
    @Override
    public String toString() {
      return s;
    }
  }
  static HashMap<String, String> h1 = new HashMap<String, String>(50);
  static {
    for (int i = 0; i < 20; i++) {
      h1.put(String.valueOf(i), String.valueOf(i));
    }
  }
  static HashMap<T1, String> h2 = new HashMap<T1, String>();
  static {
    Testor t = new Testor();
    for (int i = 0; i < 20; i++) {
      h2.put(t.new T1(String.valueOf(i)), String.valueOf(i));
    }
  }
  static HashMap<T2, String> h3 = new HashMap<T2, String>();
  static {
    for (int i = 0; i < 20; i++) {
      h3.put(t.new T2(String.valueOf(i)), String.valueOf(i));
    }
  }

  static HashMap<String, String> h4 = new HashMap<String, String>(1);
  static {
    for (int i = 0; i < 20; i++) {
      h4.put(String.valueOf(i), String.valueOf(i));
    }
  }
  
  public static void main(String[] args) {
    Iterator<Entry<String,String>> it = h1.entrySet().iterator();
    Iterator<Entry<T2,String>> it3 = h3.entrySet().iterator();
    Iterator<Entry<T1,String>> it2 = h2.entrySet().iterator();
    Iterator<Entry<String,String>> it4 = h4.entrySet().iterator();
    while (it.hasNext()) {
      String a1 = it.next().getKey();
      T1 a2 = it2.next().getKey();
      T2 a3 = it3.next().getKey();
      String a4 = it4.next().getKey();
      System.out.print(a1 + "|" + a3 + "|" + a2 + "|" + a4 + " ");
    }
  }
}