hashmap遍历实例

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package collection;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Calendar;

public class HashMapTest {

public static void main(String[] args) {
  HashMap hashmap = new HashMap();
  for (int i = 0; i < 1000; i++) {
   hashmap.put("" + i, "hello");
  }

  long bs = Calendar.getInstance().getTimeInMillis();
  Iterator iterator = hashmap.keySet().iterator();
  // String value = "";
  while (iterator.hasNext()) {
   // value = hashmap.get(iterator.next());
   System.out.println(hashmap.get(iterator.next()));
  }
  System.out.println(Calendar.getInstance().getTimeInMillis() - bs);
  listHashMap();
}

public static void listHashMap() {
  java.util.HashMap hashmap = new java.util.HashMap();
  for (int i = 0; i < 1000; i++) {
   hashmap.put("" + i, "hello");
  }
  long bs = Calendar.getInstance().getTimeInMillis();
  // Set set = hashmap.entrySet() ;
  java.util.Iterator it = hashmap.entrySet().iterator();
  while (it.hasNext()) {
   java.util.Map.Entry entry = (java.util.Map.Entry) it.next();
   // entry.getKey() 返回与此项对应的键
   // entry.getValue() 返回与此项对应的值
   System.out.println(entry.getValue());
  }
  System.out.println(Calendar.getInstance().getTimeInMillis() - bs);
}

}