java - 如何在 java 中使用 org.json.JSONObject 将值设置为 null？

Question

如何在 java 中使用 org.json.JSONObject 将值设置为 null？我当然可以通过使用 isNull 读取值是否为 null - 但似乎当我输入 null 时，它只是忽略了我:

JSONObject o = new JSONObject();
o.put("key",null);
o.isNull("key"); // returns true, buuuut...
o.has("key");    // returns false
o.isNull("somethingIHaventSetAtAll");    // also returns true, unfortunately

Answer 1

尝试设置JSONObject.NULL而不是 null:

A sentinel value used to explicitly define a name with no value. Unlike null, names with this value:

• show up in the names() array
• show up in the keys() iterator
• return true for has(String)
• do not throw on get(String)
• are included in the encoded JSON string.

This value violates the general contract of equals(Object) by returning true when compared to null. Its toString() method returns "null".