Map的幾種迭代器遍歷方式

package day05;

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

/*
 * map 的迭代
 */
public class MapIteratorDemo {

 public static void main(String[] args) {
  Map<String, String> map = new HashMap<String, String>();
  map.put("key1", "value1");
  map.put("key2", "value2");
  map.put("key3", "value3");
  map.put("key4", "value4");
  // 獲得Entry的set方法
  Set<Entry<String, String>> set = map.entrySet();
  Iterator<Entry<String, String>> i = set.iterator();
  while (i.hasNext()) {
   Entry<String, String> e = i.next();
   System.out.println(e.getKey() + ":" + e.getValue());
  }
  // 另一種遍歷方式 keySet
  Set<String> key = map.keySet();
  Iterator<String> it = key.iterator();
  while (it.hasNext()) {
   String value = map.get(it.next());
   System.out.println(value);
  }
 }

}

//

key4:value4
key3:value3
key2:value2
key1:value1

value4
value3
value2
value1