ANDROID - Send data through json response into API using HttpURLConnection

Question

I've a JSON like this:

{"AuditScheduleDetailID":12422,"AuditAnswerId":3,"LocalFindingID":9,"LocalMediaID":18,"Files":"adasdaf","ExtFiles":"jpg"}

then, when I'm Copy Paste into android project, that json is changing like :

"{\"AuditScheduleDetailID\":12422,\"AuditAnswerId\":3,\"LocalFindingID\":9," + "\"LocalMediaID\":18,\"Files\":\"adasdaf\",\"ExtFiles\":\"jpg\"}"

My Code to send data is:

public class MainActivity extends AppCompatActivity {
    String send = "{\"AuditScheduleDetailID\":12422,\"AuditAnswerId\":3,\"LocalFindingID\":9," +
            "\"LocalMediaID\":18,\"Files\":\"adasdaf\",\"ExtFiles\":\"jpg\"}";
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        uploadMedia(send);
        }
}
public void uploadMedia(String value){
        Log.d("uploading ", "test");
        Log.d("Test value : ", value);
        String urlString = "myURL"; // URL to call

        try {
            URL url = new URL(urlString);
            HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.setDoOutput(true);
            urlConnection.setChunkedStreamingMode(0);
            urlConnection.setRequestProperty("Content-Type","application/json;charset=UTF-8");
            urlConnection.setRequestProperty("Accept", "application/json");
            urlConnection.connect();

            OutputStream out = urlConnection.getOutputStream();
            BufferedWriter writer = new BufferedWriter (new OutputStreamWriter(out, "UTF-8"));
            writer.write(URLEncoder.encode(value, "UTF-8"));
            writer.flush();
            writer.close();
            out.close();
            urlConnection.connect();
        } catch (Exception e) {
            Log.d("error upload", e.getMessage());
        }
    }

but I get an error in logcat like below:

FATAL EXCEPTION: main
Process: com.example.nawadata.sqllite, PID: 8750
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.nawadata.sqllite/com.example.nawadata.sqllite.MainActivity}: java.lang.NullPointerException: println needs a message
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2193)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2243)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5019)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException: println needs a message
at android.util.Log.println_native(Native Method)
at android.util.Log.d(Log.java:139)
at com.example.nawadata.sqllite.MainActivity.uploadMedia(MainActivity.java:125)
at com.example.nawadata.sqllite.MainActivity.onCreate(MainActivity.java:51)
at android.app.Activity.performCreate(Activity.java:5231)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1104)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2157)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2243) 
at android.app.ActivityThread.access$800(ActivityThread.java:135) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:136) 
at android.app.ActivityThread.main(ActivityThread.java:5019) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:515) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 
at dalvik.system.NativeStart.main(Native Method) 

can someone help me why I keep getting error java.lang.NullPointerException: println needs a message? and how to fix it?

when im using postman to send data into api, the return message is success like this:

this

Answer 1

Try this because it seems like value is null.

Log.d("uploading ", "test");

if( !value.equals("") || !value.eqauls(" ") )

{

Log.d("Test value : ", value);

}

if this solution is not working then try Log.e instead of Log.d because Log.e is for use error purposes.

Also change this line in catch.

Log.e("error upload", e.getMessage());

Answer 2

Note: Whenever you paste a JSON response in a string variable, Android Studio automatically do the formatting which is android readable.

Change your activity code like below:

String send = "{\"AuditScheduleDetailID\":12422,\"AuditAnswerId\":3,\"LocalFindingID\":9," +
            "\"LocalMediaID\":18,\"Files\":\"adasdaf\",\"ExtFiles\":\"jpg\"}";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        uploadMedia(send);
    }

    public void uploadMedia(String value) {
        Log.e("uploading ", "test");
        Log.e("Test value : ", value);
        String urlString = "myURL"; // URL to call

        try {
            URL url = new URL(urlString);
            HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.setDoOutput(true);
            urlConnection.setChunkedStreamingMode(0);
            urlConnection.setRequestProperty("Content-Type", "application/json;charset=UTF-8");
            urlConnection.setRequestProperty("Accept", "application/json");
            urlConnection.connect();

            OutputStream out = urlConnection.getOutputStream();
            BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(out, "UTF-8"));
            writer.write(URLEncoder.encode(value, "UTF-8"));
            writer.flush();
            writer.close();
            out.close();
            urlConnection.connect();
        } catch (Exception e) {
            Log.e("error upload", e.getMessage());
        }
    }

Now run and check, if it works then please let me know.

Your logcat will be like below image.

Answer 3

use Log.e for printing error as per guide see this
Replace those lines

 Log.d("Test value : ", ""+value);


 catch (Exception e) {
            e.printStackTrace();
        }

Answer 4

replace log with this line:

   Log.d("Test value : ", value+" ");

and

  Log.d ("error upload",e.getMessage()+" ");