CODEWITHSUNDEEP
javajson
klampo
klampo

Reputation: 135

how to remove a json object from a json file?

I want to remove age from this json file using org.json or com.googlecode.json-simple?

Suppose this json objects are in a file test.json?

    {
        "age":100,
        "name":"mkyong.com",
        "messages":["msg 1","msg 2","msg 3"]
    }

After removing the file test.json should be.

    {
        "name":"mkyong.com",
        "messages":["msg 1","msg 2","msg 3"]
    }

Please tell me how to take out the json object out of the json file?

Upvotes: 3

Views: 8063

Answers (3)

Allam Kumar
Allam Kumar

Reputation: 19

I tried the same but my output is different.

JSONObject getJsonResp = (JSONObject)obj; getJsonResp.remove("messages")

Original JSON{"name":"ALK","messages":["msg 1","msg 2","msg 3"],"age":100} After Removing ["msg 1","msg 2","msg 3"]

Upvotes: 0

Koffy
Koffy

Reputation: 768

This will traverse all of the top-most keys of the Json object, and remove those that pass condition. 

    try {
        JSONObject jsonObject = (JSONObject) new JSONParser().parse(new FileReader("test.json"));
        Set keys = jsonObject.keySet();
        Iterator iterator = keys.iterator();
        while (iterator.hasNext()) {
            String key = (String) iterator.next();          
            if (key.equals("age")) {
                System.out.println("REMOVING KEY:VALUE")
                System.out.println(key + ":" + jsonObject.get(key).toString());
                iterator.remove();
                jsonObject.remove(key);
            }
        }
        try (FileWriter file = new FileWriter("test.json")) { //store data
            file.write(jsonObject.toJSONString());
            file.flush();
        }
    } catch (IOException | ParseException ex) {
        System.out.println("Error: " + ex);
    }

iterator.remove() MUST come before jsonObject.remove(key)

Upvotes: 2

Adam
Adam

Reputation: 36703

Read from file and parse

Path file = Paths.get("test.json");
String input = new String(Files.readAllBytes(file), StandardCharsets.UTF_8);
JSONObject obj = (JSONObject) JSONValue.parse(input);

Remove the key you don't want, note JSONObject implements java.util.Map...

obj.remove("age");

Encode as as String and write back to the file

String output = JSONValue.toJSONString(obj);
Files.write(file, output.getBytes(StandardCharsets.UTF_8));

Input

{"age":100,"name":"mkyong.com","messages":["msg 1","msg 2","msg 3"]}

Output

{"name":"mkyong.com","messages":["msg 1","msg 2","msg 3"]}

Upvotes: 2

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