import java.util.HashMap;

import java.util.Iterator;

public class JavaHashMap {

  public static void main(String[] args) {

  //定义HashMap

  HashMap<String, String> hm = new HashMap<String, String>();

  //添加字典

  hm.put("username", "password");

  hm.put("Jim", "1155689");

  hm.put("Jane", "1255669");

  hm.put("Kevin", "1165669");

  //测试 key 是否包含 username,返回值为 true/false

  System.out.println(hm.containsKey("username"));

  System.out.println("===================>");

  //获取 key 所对应的 vlaue

  System.out.println(hm.get("Jim"));

  System.out.println("===================>");

  //获取整个字典数据

  System.out.println(hm.entrySet());

  System.out.println("===================>");

  //循环打印每一对 key:value

  Iterator<?> it = hm.entrySet().iterator();

  while (it.hasNext()) {

  System.out.println(it.next());

  }

  System.out.println("===================>");

  //分别获取 key 的值， 和 value 的值。

  Iterator<String> it2 = hm.keySet().iterator();

  while (it2.hasNext()) {

  //获得字典的 key(username)

  String username = (String) it2.next();

  System.out.println(username);

  //获得字典的 value(节点)

  String password = hm.get(username);

  System.out.println(password);

  }

  }

}