CODEWITHSUNDEEP
javaarraysjson
th3l0n3r4n93r
th3l0n3r4n93r

Reputation: 105

Put JSONObjet into JSONArray

I have a problem putting JSONObject into JSONArray.

Here is my code:

String strObject = "{\"Code\":\"a\", \"Name\": \"b\"}";
JSONObject anExistedObject = new JSONObject(strObject);
JSONArray myArray = new JSONArray();

for(int count = 0; count < 2; count++){
    JSONObject myObject = new JSONObject;
    myObject = anExistedObject;

    myObject.put("Count", count);
    myArray.put(myObject);
}

System.out.println(myArray.toString());

Result:

[
    {
        "Code": "a",
        "Name": "b",
        "Count": 1
    },
    {
        "Code": "a",
        "Name": "b",
        "Count": 1
    }
]

What I expected:

[
    {
        "Code": "a",
        "Name": "b",
        "Count": 0
    },
    {
        "Code": "a",
        "Name": "b",
        "Count": 1
    }
]

I've read this post but still don't know how to fix mine. Did I missed something?

Upvotes: 0

Views: 81

Answers (3)

Gelldur
Gelldur

Reputation: 11558

You each time modify same object because of line: myObject = anExistedObj; You need make copy of that object instead.

Correct code:

JSONObject anExistedObj = new JSONObject();
myObject.put("Code", "a");
myObject.put("Name", "a");

JSONArray myArray = new JSONArray();
String[] keys = JSONObject.getNames(anExistedObj);

for(int count = 0; count < 2; count++){
    JSONObject myObject = new JSONObject(anExistedObj, keys);
    //anExistedObj = {"Code":"a", "Name": "b"}

    myObject.put("Count", count);
    myArray.put(myObject);
}

System.out.println(myArray.toString());

Checkout documentation of copy constructor JSONObject

Upvotes: 2

Sven Hakvoort
Sven Hakvoort

Reputation: 3621

This happens because the line myObject.put("Count", count); always modifies the same object since the variable is only a reference to the object itself. Meaning that myObject and anExistedObject point to the same object.

You should create a copy with:

JSONObject copy = new JSONObject(original, JSONObject.getNames(original));

Instead of using:

JSONObject myObject = new JSONObject;
myObject = anExistedObj;

Upvotes: 1

Elgayed
Elgayed

Reputation: 1219

You are updating and reusing anExistedObject everytime

String strObject = "{\"Code\":\"a\", \"Name\": \"b\"}";
JSONArray myArray = new JSONArray();

for(int count = 0; count < 2; count++){
    JSONObject myObject = new JSONObject(strObject);

    myObject.put("Count", count);
    myArray.put(myObject);
}

System.out.println(myArray.toString());

Upvotes: 1

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