passing JSON array from JavaScript to java and convert JSON array to java array

Question

In my application, I need to pass JSON array to java then convert that array to java array using java as a language. Here is the code.

JavaScript

  function arraytofile(rans)
  {
      myData.push(rans); // rans is the random number
      var arr = JSON.stringify(myData);// converting to json array
      android.arraytofile(arr); // passing to java
  }

Java

  public void arraytofile(String newData) throws JSONException {
      Log.d(TAG, "MainActivity.setData()");
      System.out.println(newData);
  }

newData is printing data as [[2],[3],[4]]... I want in regular java array. How I can achieve this?

Answer 1

You can use Google gson . An excellent Java library to work with JSON.

Find it here: https://code.google.com/p/google-gson/

Using gson library classes you can do something like this:

    // I took a small sample of your sample json
    String json = "[[2],[3],[4]]";
    JsonElement je = new JsonParser().parse(json);
    JsonArray jsonArray = je.getAsJsonArray();
    // I'm assuming your values are in String, you can change this if not
    List<String> javaArray = new ArrayList<String>();
    for(JsonElement jsonElement : jsonArray) {
        JsonArray individualArray = jsonElement.getAsJsonArray();
        JsonElement value = individualArray.get(0);
        // Again, I'm assuming your values are in String
        javaArray.add(value.getAsString());
    }

Now you have your json as Java List<String>. That's basically as array.

If you know exact number of results, you can surely define an array of fix size and then assign values to it.

If you know Java, than you already know how to go from here.

I hope this helps.