JAVA 復制Map對象

一.創建復制Map對象方法

    /**
     * 復制map對象
     *
     * @param paramsMap 被拷貝對象
     * @param resultMap 拷貝后的對象
     * @explain 將paramsMap中的鍵值對全部拷貝到resultMap中；
     * paramsMap中的內容不會影響到resultMap（深拷貝）
     */
    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);
        // 測試一：是否實現拷貝
        mapCopy(map1, map2);
        System.out.println(map1);// {age=20, name=Marydon}
        System.out.println(map2);// {age=20}
        // 測試二：拷貝后的map對象是否受原map對象的影響
        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  
}