JSONObject put,accumulate,element的區別

public Object put (Object key, Object value) 將value映射到key下。若是此JSONObject對象以前存在一個value在這個key下，當前的value會替換掉以前的value

Associates the specified value with the specified key in this map(optional operation). If the map previously contained . a mapping for this key, the old value is replaced by the specified value. (A map m is said to contain a mapping for a key k if and only if m.containsKey(k) would return true .))

 

public JSONObject accumulate (String key, Object value) 累積value到這個key下。這個方法同element()方法相似，特殊的是，若是當前已經存在一個value在這個key下那麼一個JSONArray將會存儲在這個key下來保存全部累積的value。若是已經存在一個JSONArray，那麼當前的value就會添加到這個JSONArray中

。相比之下replace方法會替代先前的value

Accumulate values under a key. It is similar to the element method except that if there is already an object stored 

under the key then a JSONArray is stored under the key to hold all of the accumulated values. If there is already a 

JSONArray, then the new value is appended to it. In contrast, the replace method replaces the previous value.

 

public JSONObject element (String key, Object value) 將鍵/值對放到這個JSONObject對象裏面。若是當前value爲空(null)，那麼若是這個key存在的話，這個key就會移除掉。若是這

個key以前有value值，那麼此方法會調用accumulate()方法。

Put a key/value pair in the JSONObject. If the value is null, then the key will be removed from the JSONObject if it is 

present. If there is a previous value assigned to the key, it will call accumulate.