JAVA 复制Map对象

一.创建复制Map对象方法

    /**
     * 复制map对象
     *
     * @param paramsMap 被拷贝对象
     * @param resultMap 拷贝后的对象
     * @explain 将paramsMap中的键值对全部拷贝到resultMap中；
     * paramsMap中的内容不会影响到resultMap（深拷贝）
     */
    public static void mapCopy(Map resultMap, Map paramsMap) {
        if (resultMap == null) resultMap = new HashMap();
        if (paramsMap == null) return;

        Iterator it = paramsMap.entrySet().iterator();
        while (it.hasNext()) {
            Map.Entry entry = (Map.Entry) it.next();
            Object key = entry.getKey();
            resultMap.put(key, paramsMap.get(key) != null ? paramsMap.get(key) : "");

        }
    }


public static void main(String[] args) {
   Map<String, String> map1 = new HashMap<String, String>(1);
        map1.put("name", "Marydon");
        Map<String, Object> map2 = new HashMap<String, Object>(1);
        map2.put("age", 20);
        // 测试一：是否实现拷贝
        mapCopy(map1, map2);
        System.out.println(map1);// {age=20, name=Marydon}
        System.out.println(map2);// {age=20}
        // 测试二：拷贝后的map对象是否受原map对象的影响
        map2.clear();
        System.out.println(map1);// {age=20, name=Marydon}
        System.out.println(map2);// {}

        System.out.println("================================");
        HashMap<String, Object> hm = new HashMap();
        HashMap<String, Object> hmCopy = new HashMap();
        hm.put("123", 123);
        System.out.println(hm.get("123")); //123
        hmCopy = hm;
        hmCopy.remove("123");
        System.out.println(hm.get("123"));//null  
}