Check if JSON response contains certain value

Question

So I'm building an Android app in Android Studio for an excisting webpage with a login feature. I connected the app succesfully to the websites database already and I can login and get a response from the server. The app is looking for an error value in the response, but the response contains no error value.

This is the code in my app:

public void onResponse(String response) {
            Log.d(TAG, "Login Response: " + response.toString());
            hideDialog();

            try {
                JSONObject jObj = new JSONObject(response);
                boolean error = jObj.getBoolean("error");

                // Check for error node in json
                if (!error) {
                    // user successfully logged in
                    // Create login session
                    session.setLogin(true);


                    // Launch main activity
                    Intent intent = new Intent(LoginActivity.this,
                            MainActivity.class);
                    startActivity(intent);
                    finish();

This is the response the server gives when the login was succesfull:

Login Response: {"howislife":1,"rekeningnummer":"212220","soortuser":"student","datum":"05 Sep 2017"}

So when the login was succesfull it says "howislife:1", when the password or username is incorrect it says "howislife:2" or "howislife:3". So the code in my Android app needs to check what value "howislife" is . How can I do that? Thanks in advance!

Answer 1

Try this code,

int howislife = (!jsonObjects.isNull("howislife")) ?
                                        jsonObjects.optInt("howislife") : 0;
            if (howislife == 1) {
                //login sucess
            } else {
               //login failed
            }

Answer 2

I assume your api gives response always with those parameters and if the response comes empty or null then check for it before converting to JSONObject , then you could try below code, it will work.

JSONObject jObj = new JSONObject(response);
            if(jObj.getInt("howislife")==1){
                  System.out.println("Login success");
            }else{
                  System.out.println("Login fail");
            }

Answer 3

There is a function "has()" to check keys for JSONObject in Android.

boolean has (String name) Returns true if this object has a mapping for name. The mapping may be NULL.

More details:

https://developer.android.com/reference/org/json/JSONObject.html#has(java.lang.String)

Answer 4

I solved it using this code already, thanks!

public void onResponse(String response) {
            Log.d(TAG, "Login Response: " + response.toString());
            hideDialog();

            try {
                JSONObject jObj = new JSONObject(response);
                int login1 = jObj.getInt("howislife");
                System.out.println(login1);
                //Check for error node in json
                if (login1 == 1) {
                    // user successfully logged in
                    // Create login session
                    session.setLogin(true);


                    // Launch main activity
                    Intent intent = new Intent(LoginActivity.this,
                            MainActivity.class);
                    startActivity(intent);
                    finish();
                } else if(login1 == 2) {
                    Toast.makeText(getApplicationContext(), "Wachtwoord verkeerd", Toast.LENGTH_LONG).show();
                } else if(login1 == 3) {
                    Toast.makeText(getApplicationContext(), "Gebruikersnaam of/en wachtwoord verkeerd", Toast.LENGTH_LONG).show();
                } else {
                    Toast.makeText(getApplicationContext(), "Er is iets fout gegaan, probeer opnieuw.", Toast.LENGTH_LONG).show();
                }
            } catch (JSONException e) {
                // JSON error
                e.printStackTrace();

            }

        }