How do I read from JSON File in Java?

Question

I've read some other questions about this, but they did not seem to help me. As the title says, I want to know how to read from .json files using Java. Eg. I want my program to read a boolean value. (That is what I want it to.)

I really hope you will be able to help me with this. I am able to use json-simple-1.1.1 if needed.

What I've found so far (That did not work):

    String str = "Name";
    JSONObject obj = new JSONObject();
    String n = (String) obj.get("Name");
    if (!n.equals("true")) {

    } else
    if (n.equals("true")) {
        ButtonsShow = true;
    } else if (n.equals("false")) {
        ButtonsShow = false;
    }

Click to view the .Json file

score 0 · Answer 1 · answered Nov 28 '15 at 10:19

0

you try it:

  import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.Iterator;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;

public class JsonSimpleExample {
     public static void main(String[] args) {

    JSONParser parser = new JSONParser();

    try {

        Object obj = parser.parse(new FileReader("c:\\test.json"));

        JSONObject jsonObject = (JSONObject) obj;

        String name = (String) jsonObject.get("name");
        System.out.println(name);

        long age = (Long) jsonObject.get("age");
        System.out.println(age);

        // loop array
        JSONArray msg = (JSONArray) jsonObject.get("messages");
        Iterator<String> iterator = msg.iterator();
        while (iterator.hasNext()) {
            System.out.println(iterator.next());
        }

    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } catch (ParseException e) {
        e.printStackTrace();
    }

     }

}

answered Nov 28 '15 at 10:19

Kumaresan Perumal

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take a look at it : http://www.mkyong.com/java/json-simple-example-read-and-write-json/ – Kumaresan Perumal Nov 28 '15 at 10:20
http://www.tutorialspoint.com/json/json_java_example.htm – Kumaresan Perumal Nov 28 '15 at 10:22
Read that link, I don't see it says anything about how to read JSON using Java? Can you please show me? – ApplePie Nov 28 '15 at 10:30
what do you mean? you read those things. do it yourself. it uses java – Kumaresan Perumal Nov 28 '15 at 10:31
Sorry. Alright so I am trying to read the JSON. Right now I use this code (Below). But when I try to toggle the buttons, it keeps doing as if it the boolean was set to true. By the way. I know the options.json is set to false. – ApplePie Nov 28 '15 at 10:35
JSONParser parser = new JSONParser(); Object obj = null; try { obj = parser.parse(new FileReader("Options.json")); } catch (ParseException e) { // TODO Auto-generated catch block e.printStackTrace(); } JSONObject jsonObject = (JSONObject) obj; Boolean truth = (Boolean) jsonObject.get("Button"); if (truth.valueOf(true)) { ButtonsShow = true; System.out.print(obj); } else if (truth.valueOf(false)) { ButtonsShow = false; System.out.print(obj); } – ApplePie Nov 28 '15 at 10:35
By the way, I use a loop that runs every 1ms. – ApplePie Nov 28 '15 at 10:35
https://www.dropbox.com/s/men3wt58wgkuvd6/Options.json?dl=1 – ApplePie Nov 28 '15 at 10:39
{"button":false} i have got on it. – Kumaresan Perumal Nov 28 '15 at 10:48
you can get it like String button = (String) jsonObject.get("button"); – Kumaresan Perumal Nov 28 '15 at 10:51
I get this error. Any idea why? java.lang.ClassCastException: java.lang.Boolean cannot be cast to java.lang.String - I can't see why myself.. – ApplePie Nov 28 '15 at 10:59
Nevermind - Fixed it. Thanks! – ApplePie Nov 28 '15 at 11:00

How do I read from JSON File in Java?

1 Answers1