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How to increase speed of BLE scanning Android Studio?

I want make some application, it will scanning nearby BLE and sending to server via MQTT. But the scanning proccess to slow. I want to increase the speed of scanning.
mainActivity.java
package com.example.mqtt_active;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import android.Manifest;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import org.eclipse.paho.android.service.MqttAndroidClient;
import org.eclipse.paho.client.mqttv3.IMqttActionListener;
import org.eclipse.paho.client.mqttv3.IMqttToken;
import org.eclipse.paho.client.mqttv3.MqttException;
import java.nio.charset.StandardCharsets;
public class MainActivity extends AppCompatActivity {
private Button turnon, changeLayout;
MqttAndroidClient client;
private boolean state=false;
private BluetoothAdapter bluetoothAdapter;
public static final int REQUEST_ACCESS_COARSE_LOCATION = 1;
public static final int REQUEST_ENABLE_BLUETOOTH = 11;
public static String mqtt_server,mqtt_port,mqtt_id;
private TextView textView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getSupportActionBar().hide();
setContentView(R.layout.activity_main);
turnon = findViewById(R.id.turnon);
changeLayout = findViewById(R.id.mqttSet);
bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
textView = findViewById(R.id.textView4);
textView.setText("id "+mqtt_id+" port "+mqtt_port+" server "+mqtt_server);
client = new MqttAndroidClient(this.getApplicationContext(), "tcp://"+mqtt_server+":"+mqtt_port,mqtt_id);
final Handler handler = new Handler();
handler.postDelayed(new Runnable() {
#Override
public void run() {
stateCheck();
handler.postDelayed(this, 1000);
}
}, 1000);
final Handler handlerStop = new Handler();
handlerStop.postDelayed(new Runnable() {
#Override
public void run() {
bluetoothAdapter.cancelDiscovery();
handlerStop.postDelayed(this, 2000);
}
}, 2000);
turnon.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
if (!state){
turnon.setText("Turn Off");
// if (bluetoothAdapter!=null & bluetoothAdapter.isEnabled()) {
// if(checkCoarsePermission()){
// bluetoothAdapter.startDiscovery();
// }
// }
if(mqtt_server!=null||mqtt_id!=null||mqtt_port!=null){
try {
IMqttToken token = client.connect();
token.setActionCallback(new IMqttActionListener() {
#Override
public void onSuccess(IMqttToken asyncActionToken) {
Toast.makeText(MainActivity.this,"connected!!",Toast.LENGTH_LONG).show();
}
#Override
public void onFailure(IMqttToken asyncActionToken, Throwable exception) {
Toast.makeText(MainActivity.this,"connection failed!!",Toast.LENGTH_LONG).show();
}
});
} catch (MqttException e) {
e.printStackTrace();
}}
state = true;
}else{
turnon.setText("Turn On");
state = false;
// bluetoothAdapter.cancelDiscovery();
}
}
});
changeLayout.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
startActivity(new Intent(MainActivity.this,MqttActivity.class));
}
});
}
public void stateCheck(){
if (state){
if (bluetoothAdapter!=null & bluetoothAdapter.isEnabled()) {
if(checkCoarsePermission()){
bluetoothAdapter.startDiscovery();
}
}
}else {
bluetoothAdapter.cancelDiscovery();
}
}
private boolean checkCoarsePermission(){
if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION)
!= PackageManager.PERMISSION_GRANTED){
ActivityCompat.requestPermissions(this, new String[] {Manifest.permission.ACCESS_COARSE_LOCATION},
REQUEST_ACCESS_COARSE_LOCATION);
return false;
}else {
return true;
}
}
#Override
protected void onResume() {
super.onResume();
registerReceiver(devicesFoundReceiver, new IntentFilter(BluetoothDevice.ACTION_FOUND));
registerReceiver(devicesFoundReceiver, new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_STARTED));
registerReceiver(devicesFoundReceiver, new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED));
}
#Override
protected void onPause() {
super.onPause();
unregisterReceiver(devicesFoundReceiver);
}
private final BroadcastReceiver devicesFoundReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String action= intent.getAction();
if(BluetoothDevice.ACTION_FOUND.equals(action)){
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
int rssi = intent.getShortExtra(BluetoothDevice.EXTRA_RSSI,Short.MIN_VALUE);
String RSSI = String.valueOf(rssi);
Toast.makeText(context.getApplicationContext(),"rssi "+RSSI+" "+device.getAddress(),Toast.LENGTH_SHORT).show();
if(mqtt_server!=null||mqtt_id!=null||mqtt_port!=null){
try {
String payload = "rssi:"+RSSI+"mac:"+device.getAddress();
client.publish("test",payload.getBytes(),0,false);
} catch ( MqttException e) {
e.printStackTrace();
}}
}else if(BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)){
}else if(BluetoothAdapter.ACTION_DISCOVERY_STARTED.equals(action)){
}
}
};
#Override
public void onRequestPermissionsResult(int requestCode, #NonNull String[] permissions, #NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
switch (requestCode){
case REQUEST_ACCESS_COARSE_LOCATION:
if(grantResults.length>0 && grantResults[0] == PackageManager.PERMISSION_GRANTED){
Toast.makeText(this,"ALLOWED", Toast.LENGTH_SHORT).show();
}else {
Toast.makeText(this,"Forbidden",Toast.LENGTH_SHORT).show();
} break;
}
}
}
mqttActivity.java
package com.example.mqtt_active;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
public class MqttActivity extends AppCompatActivity {
private EditText server,port,id;
private Button save;
#Override
protected void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_mqtt);
server = findViewById(R.id.serverMQTT);
id = findViewById(R.id.mqttTopic);
port = findViewById(R.id.mqttPort);
save = findViewById(R.id.saveButton);
save.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
MainActivity.mqtt_id = id.getText().toString();
MainActivity.mqtt_port = port.getText().toString();
MainActivity.mqtt_server = server.getText().toString();
startActivity(new Intent(MqttActivity.this,MainActivity.class));
}
});
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".MainActivity">
<Button
android:id="#+id/turnon"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Turn On"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.452" />
<Button
android:id="#+id/mqttSet"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Set MQTT"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.511"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/turnon"
app:layout_constraintVertical_bias="0.073" />
<TextView
android:id="#+id/textView4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="52dp"
android:text="TextView"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.524"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/mqttSet"
app:layout_constraintVertical_bias="0.0" />
</androidx.constraintlayout.widget.ConstraintLayout>
activity_mqtt.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<EditText
android:id="#+id/serverMQTT"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:ems="10"
android:inputType="textPersonName"
android:text="Server"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.497"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/textView" />
<TextView
android:id="#+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="60dp"
android:text="MQTT SERVER"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="24dp"
android:text="MQTT TOPIC"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.498"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/serverMQTT" />
<EditText
android:id="#+id/mqttTopic"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:ems="10"
android:inputType="textPersonName"
android:text="Topic"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/textView2" />
<TextView
android:id="#+id/textView3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="24dp"
android:text="MQTT PORT"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/mqttTopic" />
<EditText
android:id="#+id/mqttPort"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:ems="10"
android:inputType="textPersonName"
android:text="Port"
app:layout_constraintBottom_toTopOf="#+id/saveButton"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.497"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/textView3"
app:layout_constraintVertical_bias="0.0" />
<Button
android:id="#+id/saveButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Save"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.498"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="#+id/textView3"
app:layout_constraintVertical_bias="0.298" />
</androidx.constraintlayout.widget.ConstraintLayout>
How to increase speed of scanning nearby BLE? i expect from this forum, i can increase speed of scanning nearby BLE.

I am making OCR Reader Application. When I create the PDF of generated text, it is not saved as I want. There is one problem in the while loop

To save this PDF I have added a while loop where the last letter has added a specific number from 0 to n in parentheses. When I save the first PDF it is saved as myPDFfile.pdf then the second pdf will be saved as myPDFFile(1).pdf but when I save the third pdf it will be saved as myPDFFile(1)(1).pdf
but I want this pdf to save as myPDFfile(2).pdf.
import static android.Manifest.permission.CAMERA;
import android.Manifest;
import android.content.Context;
import android.content.pm.PackageManager;
import android.graphics.Paint;
import android.graphics.pdf.PdfDocument;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.Looper;
import android.speech.tts.TextToSpeech;
import android.util.SparseArray;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import com.google.android.gms.vision.CameraSource;
import com.google.android.gms.vision.Detector;
import com.google.android.gms.vision.text.TextBlock;
import com.google.android.gms.vision.text.TextRecognizer;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Locale;
public class MainActivity extends AppCompatActivity {
private TextView textView;
private SurfaceView surfaceView;
private CameraSource cameraSource;
private TextRecognizer textRecognizer;
Button button;
private TextToSpeech textToSpeech;
private String stringResult = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button = findViewById(R.id.btn);
button = findViewById(R.id.btn1);
ActivityCompat.requestPermissions(this, new String[]{CAMERA}, PackageManager.PERMISSION_GRANTED);
textToSpeech = new TextToSpeech(this, new TextToSpeech.OnInitListener() {
#Override
public void onInit(int status) {
textToSpeech.setLanguage(Locale.US);
}
});
}
#Override
protected void onDestroy() {
super.onDestroy();
cameraSource.release();
}
private void textRecognizer() {
textRecognizer = new TextRecognizer.Builder(getApplicationContext()).build();
cameraSource = new CameraSource.Builder(getApplicationContext(), textRecognizer)
.setRequestedPreviewSize(1280, 1024)
.setAutoFocusEnabled(true)
.build();
surfaceView = findViewById(R.id.surfaceView);
Context context = this;
surfaceView.getHolder().addCallback(new SurfaceHolder.Callback() {
#Override
public void surfaceCreated(SurfaceHolder holder) {
try {
if (ActivityCompat.checkSelfPermission(context, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
// TODO: Consider calling
// ActivityCompat#requestPermissions
// here to request the missing permissions, and then overriding
// public void onRequestPermissionsResult(int requestCode, String[] permissions,
// int[] grantResults)
// to handle the case where the user grants the permission. See the documentation
// for ActivityCompat#requestPermissions for more details.
return;
}
cameraSource.start(surfaceView.getHolder());
} catch (IOException e) {
e.printStackTrace();
}
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
}
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
cameraSource.stop();
}
});
}
private void capture() {
textRecognizer.setProcessor(new Detector.Processor<TextBlock>() {
#Override
public void release() {
}
#Override
public void receiveDetections(Detector.Detections<TextBlock> detections) {
SparseArray<TextBlock> sparseArray = detections.getDetectedItems();
StringBuilder stringBuilder = new StringBuilder();
for (int i = 0; i < sparseArray.size(); ++i) {
TextBlock textBlock = sparseArray.valueAt(i);
if (textBlock != null && textBlock.getValue() != null) {
stringBuilder.append(textBlock.getValue() + " ");
}
}
final String stringText = stringBuilder.toString();
Handler handler = new Handler(Looper.getMainLooper());
handler.post(new Runnable() {
#Override
public void run() {
stringResult = stringText;
resultObtained();
}
});
}
});
}
private void resultObtained() {
setContentView(R.layout.activity_main);
textView = findViewById(R.id.textView);
textView.setText(stringResult);
textToSpeech.speak(stringResult, TextToSpeech.QUEUE_FLUSH, null, null);
}
public void buttonStart(View view) {
setContentView(R.layout.surface);
Button capture = findViewById(R.id.capture);
capture.setOnClickListener(v -> capture());
textRecognizer();
}
public void createMyPDF(View view) {
PdfDocument myPdfDocument = new PdfDocument();
PdfDocument.PageInfo myPageInfo = new PdfDocument.PageInfo.Builder(300, 600, 1).create();
PdfDocument.Page myPage = myPdfDocument.startPage(myPageInfo);
Paint myPaint = new Paint();
String myString = textView.getText().toString();
int x = 10, y = 25;
for (String line : myString.split("\n")) {
myPage.getCanvas().drawText(line, x, y, myPaint);
y += myPaint.descent() - myPaint.ascent();
}
myPdfDocument.finishPage(myPage);
String myFilePath = Environment.getExternalStorageDirectory().getPath() + "/myPDFFile.pdf";
File myFile = new File(myFilePath);
while (myFile.exists()) {
int i = 0;
i++;
myFile = new File(myFile.toString().replace("myPDFFile", "myPDFFile (" + i + ")"));
}
try {
myPdfDocument.writeTo(new FileOutputStream(myFile));
} catch (Exception e) {
e.printStackTrace();
textView.setText("ERROR");
}
myPdfDocument.close();
}
public void onPause() {
if (textToSpeech != null) {
textToSpeech.stop();
}
super.onPause();
}
}
XML Code:-
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
tools:context=".MainActivity"
android:layout_height="match_parent">
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_marginStart="-2dp"
android:layout_marginTop="-4dp">
<TextView
android:id="#+id/textView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentTop="true"
android:layout_marginStart="-4dp"
android:layout_marginTop="-2dp"
android:background="#color/black"
android:gravity="center"
android:text="OCR READER FOR VISUALLY IMPARED PEOPLES"
android:textColor="#color/white"
android:textIsSelectable="true"
android:textSize="20dp"
android:textStyle="bold"
tools:layout_editor_absoluteX="8dp" />
</ScrollView>
<Button
android:id="#+id/btn"
android:layout_width="407dp"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginStart="0dp"
android:layout_marginBottom="24dp"
android:onClick="buttonStart"
android:text="Click here"
android:textSize="20dp" />
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/btn1"
android:layout_alignBottom="#+id/btn"
android:layout_alignParentStart="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="45dp"
android:onClick="createMyPDF"
android:text="Create PDF"
android:textSize="20dp" />
</RelativeLayout>
surface.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto">
<SurfaceView
android:id="#+id/surfaceView"
android:layout_width="378dp"
android:layout_height="628dp"
android:layout_marginStart="16dp"
android:layout_marginTop="4dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent"
android:id="#+id/capture"
android:layout_marginHorizontal="32dp"
android:layout_marginBottom="32dp"
android:text="Capture"
app:layout_constraintEnd_toEndOf="parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>

How to fix activity not showing when run

I am creating a chat app in which you can create groups. to create groups I have created a new activity. it shows up in preview but won't show up when I run the app and open the activity. I tried on another phone and only the CircleImageView showed up. but it's OnClickListner won't work. there are no errors while compiling, logging or debbugging.
I have even tried breakpoints to check the error, but no output. Exept for the ad shows up. tried changing layouts but nothing shows up.
I don't know the error so I am pasting the CreateGroupActivity.java file as well as activity_create_group.xml
CreateGroupActivity.java:
package com.satyamedh.chitchatmessenger;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import com.google.android.gms.ads.AdListener;
import com.google.android.gms.ads.AdRequest;
import com.google.android.gms.ads.AdView;
import com.google.android.gms.ads.MobileAds;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.theartofdev.edmodo.cropper.CropImage;
import com.theartofdev.edmodo.cropper.CropImageView;
import de.hdodenhof.circleimageview.CircleImageView;
public class CreateGroupActivity extends AppCompatActivity
{
private CircleImageView circleImageView;
private EditText editText;
private Button buttonconf, buttoncanc;
private final static int chosenProfileImage = 1;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_create_group);
initializeFields();
buttoncanc.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent profileIntent = new Intent(CreateGroupActivity.this, MainActivity.class);
startActivity(profileIntent);
}
});
buttonconf.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (TextUtils.isEmpty(editText.getText())){
Toast.makeText(CreateGroupActivity.this, "Please enter text..", Toast.LENGTH_SHORT).show();
}
}
});
circleImageView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent galleryIntent = new Intent();
galleryIntent.setAction(Intent.ACTION_GET_CONTENT);
galleryIntent.setType("image/*");
startActivityForResult(galleryIntent, chosenProfileImage);
}
});
}
#Override
protected void onActivityResult(int requestCode, int resultCode, #Nullable Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if(requestCode == chosenProfileImage && resultCode == RESULT_OK && data != null)
{
Uri imageUri = data.getData();
CropImage
.activity()
.setGuidelines(CropImageView.Guidelines.ON)
.start(this);
}
if (requestCode == CropImage.CROP_IMAGE_ACTIVITY_REQUEST_CODE)
{
final CropImage.ActivityResult result = CropImage.getActivityResult(data);
if(resultCode == RESULT_OK) {
assert result != null;
Uri resultUri = result.getUri();
DatabaseReference rootref = FirebaseDatabase.getInstance().getReference();
Intent settingsIntent = new Intent(CreateGroupActivity.this, chooseUserActivity.class);
String key = rootref.push().getKey();
settingsIntent.putExtra("groupKey", key);
settingsIntent.putExtra("groupImage", resultUri);
settingsIntent.putExtra("groupName", editText.getText().toString());
startActivity(settingsIntent);
}
}
}
private void initializeFields()
{
MobileAds.initialize(this, "ca-app-pub-3127817354023186~6842500243");
final AdView mAdView;
mAdView = findViewById(R.id.my_adView_createGroup);
AdRequest adRequest = new AdRequest.Builder().build();
mAdView.loadAd(adRequest);
mAdView.setAdListener(new AdListener() {
#Override
public void onAdLoaded() {
// Code to be executed when an ad finishes loading.
}
#Override
public void onAdFailedToLoad(int errorCode) {
// Code to be executed when an ad request fails.
}
#Override
public void onAdOpened() {
// Code to be executed when an ad opens an overlay that
// covers the screen.
}
#Override
public void onAdClicked() {
// Code to be executed when the user clicks on an ad.
}
#Override
public void onAdLeftApplication() {
// Code to be executed when the user has left the app.
}
#Override
public void onAdClosed() {
// Code to be executed when the user is about to return
// to the app after tapping on an ad.
}
});
circleImageView = findViewById(R.id.create_group_image);
editText = findViewById(R.id.create_group_name);
buttonconf = findViewById(R.id.confirm_button);
buttoncanc = findViewById(R.id.cancel_button);
}
}
activity_create_group.xml:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".CreateGroupActivity">
<de.hdodenhof.circleimageview.CircleImageView
android:layout_width="100dp"
android:layout_height="100dp"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_alignParentEnd="true"
android:layout_alignParentBottom="true"
android:layout_marginStart="51dp"
android:layout_marginTop="87dp"
android:layout_marginEnd="259dp"
android:layout_marginBottom="551dp"
android:src="#drawable/profile_image"
android:id="#+id/create_group_image"/>
<EditText
android:layout_width="250dp"
android:layout_height="50dp"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_alignParentEnd="true"
android:layout_alignParentBottom="true"
android:layout_marginStart="167dp"
android:layout_marginTop="88dp"
android:layout_marginEnd="4dp"
android:layout_marginBottom="596dp"
android:background="#drawable/inputs"
android:id="#+id/create_group_name"
android:inputType="text"
android:hint="Group name here"/>
<Button
android:id="#+id/confirm_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_alignParentEnd="true"
android:layout_alignParentBottom="true"
android:layout_marginStart="168dp"
android:layout_marginTop="141dp"
android:layout_marginEnd="156dp"
android:layout_marginBottom="542dp"
android:text="Confirm"
android:background="#drawable/buttons"/>
<Button
android:id="#+id/cancel_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_alignParentEnd="true"
android:layout_alignParentBottom="true"
android:layout_marginStart="263dp"
android:layout_marginTop="140dp"
android:layout_marginEnd="60dp"
android:layout_marginBottom="546dp"
android:text="Cancel"
android:background="#drawable/buttons"/>
<com.google.android.gms.ads.AdView
xmlns:ads="http://schemas.android.com/apk/res-auto"
android:id="#+id/my_adView_createGroup"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_alignParentBottom="true"
ads:adSize="SMART_BANNER"
ads:adUnitId="ca-app-pub-3940256099942544/6300978111">
</com.google.android.gms.ads.AdView>
</RelativeLayout>
android phone(redmi 2) screenshot:
https://drive.google.com/file/d/18MMzLvcdIi8iLog1nR_NrJPcJf-NZG51/view?usp=sharing
pc android studio screenshot:
https://drive.google.com/file/d/1E3Suy967AS3aQS9TEkUlAh5kPjWr86u-/view?usp=sharing
I am newbie to stackoverflow so I can't attach images. sorry.
no errors also.

it's normal because you used so much alignment value and attribute which made your layout not responsive , please use the xml below and don't forget to add the image:src and background you wanted
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".CreateGroupActivity">
<de.hdodenhof.circleimageview.CircleImageView
android:layout_width="100dp"
android:layout_height="100dp"
android:layout_margin="20dp"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:id="#+id/create_group_image"/>
<EditText
android:layout_toRightOf="#id/create_group_image"
android:layout_width="250dp"
android:layout_marginTop="20dp"
android:layout_height="wrap_content"
android:id="#+id/create_group_name"
android:inputType="text"
android:hint="Group name here"/>
<Button
android:layout_below="#id/create_group_name"
android:layout_toRightOf="#id/create_group_image"
android:id="#+id/confirm_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Confirm"/>
<Button
android:layout_below="#id/create_group_name"
android:layout_toRightOf="#id/confirm_button"
android:id="#+id/cancel_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Cancel"/>
<com.google.android.gms.ads.AdView
xmlns:ads="http://schemas.android.com/apk/res-auto"
android:id="#+id/my_adView_createGroup"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_alignParentBottom="true"
ads:adSize="SMART_BANNER"
ads:adUnitId="ca-app-pub-3940256099942544/6300978111">
</com.google.android.gms.ads.AdView>
</RelativeLayout>

NullPointerException in Android app (Bundle?) [duplicate]

This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 6 years ago.
In a class i am taking we have been learning some android app development and such, and i have managed to run into a problem that I, for the life of me, cannot figure out...
Basic background...
I get a nullpointerexception when I rotate the device... This error is located at Line 100 of QuizActivity.....
this Line is : mCheatButton.setOnClickListener(new View.OnClickListener() {//....
I suspect this has something to do with storing or retrieving information from the bundle...
Anyways here is the rest of The code....
Here is my quiz activity... Sorry for all the code blocks, I dont really know a better way to give you this information, or if you even need all of it.... But right now I just can figure out what is going on... so i have printed the error (stack trace? i think that is the right term...).. here as well...
03-02 09:49:28.858 7921-7921/com.example.ryan.ryans_quiz E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.ryan.ryans_quiz, PID: 7921
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.ryan.ryans_quiz/com.example.ryan.ryans_quiz.QuizActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at com.example.ryan.ryans_quiz.QuizActivity.onCreate(QuizActivity.java:100)
at android.app.Activity.performCreate(Activity.java:6237)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 
at android.app.ActivityThread.-wrap11(ActivityThread.java) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:148) 
at android.app.ActivityThread.main(ActivityThread.java:5417) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
QuizActivity
package com.example.ryan.ryans_quiz;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.TextView;
import android.widget.Toast;
public class QuizActivity extends AppCompatActivity {
private static final String TAG = "QuizActivity";
private static final String KEY_INDEX = "index";
private static final int REQUEST_CODE_CHEAT = 0;
private Button mTrueButton;
private Button mFalseButton;
private ImageButton mNextButton;
private Button mCheatButton;
private TextView mQuestionTextView;
private Question[] mQuestionBank = new Question[] {
new Question(R.string.question_oceans, true),
new Question(R.string.question_mideast, false),
new Question(R.string.question_africa, false),
new Question(R.string.question_americas, true),
new Question(R.string.question_asia, true)
};
private int mCurrentIndex = 0;
private boolean mIsCheater;
private void updateQuestion() {
int question = mQuestionBank[mCurrentIndex].getTextResId();
mQuestionTextView.setText(question);
}
private void checkAnswer(boolean userPressedTrue) {
boolean answerIsTrue = mQuestionBank[mCurrentIndex].isAnswerTrue();
int messageResId = 0;
if (mIsCheater) {
messageResId = R.string.judgment_toast;
} else {
if (userPressedTrue == answerIsTrue) {
messageResId = R.string.correct_toast;
} else {
messageResId = R.string.incorrect_toast;
}
}
Toast.makeText(this, messageResId, Toast.LENGTH_SHORT)
.show();
}
#Override
protected void onCreate(Bundle savedInstanceState) {
if (savedInstanceState != null) {
mCurrentIndex = savedInstanceState.getInt(KEY_INDEX, 0);
}
super.onCreate(savedInstanceState);
Log.d(TAG, "onCreate(Bundle) called");
setContentView(R.layout.activity_quiz);
mQuestionTextView = (TextView) findViewById(R.id.question_text_view);
mTrueButton = (Button) findViewById(R.id.trueButton);
mTrueButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
checkAnswer(true);
}
});
mFalseButton = (Button) findViewById(R.id.falseButton);
mFalseButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
checkAnswer(false);
}
});
mNextButton = (ImageButton) findViewById(R.id.nextButton);
mNextButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
mCurrentIndex = (mCurrentIndex + 1) % mQuestionBank.length;
mIsCheater = false;
updateQuestion();
}
});
mCheatButton = (Button)findViewById(R.id.cheatButton);
mCheatButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
boolean answerIsTrue = mQuestionBank[mCurrentIndex].isAnswerTrue();
Intent i = CheatActivity.newIntent(QuizActivity.this, answerIsTrue);
startActivityForResult(i, REQUEST_CODE_CHEAT);
}
});
updateQuestion();
}
#Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putInt(KEY_INDEX, mCurrentIndex);
}
#Override
protected void onStart() {
super.onStart();
Log.d(TAG, "onStart() called");
}
#Override
protected void onPause() {
super.onPause();
Log.d(TAG, "onPause() called");
}
#Override
protected void onResume() {
super.onResume();
Log.d(TAG, "onResume() called");
}
#Override
protected void onStop() {
super.onStop();
Log.d(TAG, "onStop() called");
}
#Override
protected void onDestroy() {
super.onDestroy();
Log.d(TAG, "onDestroy() called");
}
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (resultCode != Activity.RESULT_OK) {
return;
}
if (requestCode == REQUEST_CODE_CHEAT) {
if (data == null) {
return;
}
mIsCheater = CheatActivity.wasAnswerShown(data);
}
}
}
My CheatActivity class
package com.example.ryan.ryans_quiz;
import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.content.Context;
import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewAnimationUtils;
import android.widget.Button;
import android.widget.TextView;
public class
CheatActivity extends AppCompatActivity {
private static final String EXTRA_ANSWER_IS_TRUE =
"com.bignerdranch.android.geoquiz.answer_is_true";
private static final String EXTRA_ANSWER_SHOWN =
"com.bignerdranch.android.geoquiz.answer_shown";
private boolean mAnswerIsTrue;
private TextView mAnswerTextView;
private Button mShowAnswer;
public static Intent newIntent(Context packageContext, boolean answerIsTrue) {
Intent i = new Intent(packageContext, CheatActivity.class);
i.putExtra(EXTRA_ANSWER_IS_TRUE, answerIsTrue);
return i;
}
public static boolean wasAnswerShown(Intent result) {
return result.getBooleanExtra(EXTRA_ANSWER_SHOWN, false);
}
private void setAnswerShownResult(boolean isAnswerShown) {
Intent data = new Intent();
data.putExtra(EXTRA_ANSWER_SHOWN, isAnswerShown);
setResult(RESULT_OK, data);
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_cheat);
mAnswerIsTrue = getIntent().getBooleanExtra(EXTRA_ANSWER_IS_TRUE, false);
mAnswerTextView = (TextView)findViewById(R.id.answer_text_view);
mShowAnswer = (Button)findViewById(R.id.show_answer_button);
mShowAnswer.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (mAnswerIsTrue) {
mAnswerTextView.setText(R.string.trueButton);
} else {
mAnswerTextView.setText(R.string.falseButton);
}
setAnswerShownResult(true);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
int cx = mShowAnswer.getWidth() / 2;
int cy = mShowAnswer.getHeight() / 2;
float radius = mShowAnswer.getWidth();
Animator anim = ViewAnimationUtils
.createCircularReveal(mShowAnswer, cx, cy, radius, 0);
anim.addListener(new AnimatorListenerAdapter() {
#Override
public void onAnimationEnd(Animator animation) {
super.onAnimationEnd(animation);
mAnswerTextView.setVisibility(View.VISIBLE);
mShowAnswer.setVisibility(View.INVISIBLE);
}
});
anim.start();
} else {
mAnswerTextView.setVisibility(View.VISIBLE);
mShowAnswer.setVisibility(View.INVISIBLE);
}
}
});
}
my Question Class
package com.example.ryan.ryans_quiz;
/**
* Created by Ryan on 1/20/2016.
*/
public class Question {
private int mTextResId;
private boolean mAnswerTrue;
public Question(int _textResId, boolean _answerTrue) {
mTextResId = _textResId;
mAnswerTrue = _answerTrue;
}
public int getTextResId() {
return mTextResId;
}
public void setTextResId(int textResId) {
mTextResId = textResId;
}
public boolean isAnswerTrue() {
return mAnswerTrue;
}
public void setAnswerTrue(boolean answerTrue) {
mAnswerTrue = answerTrue;
}
}
And finally my xml Files....
activity_cheat
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:orientation="vertical"
tools:context="com.example.ryan.ryans_quiz.CheatActivity">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:padding="24dp"
android:text="#string/warning_text"/>
<TextView
android:id="#+id/answer_text_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:padding="24dp"
tools:text="Answer"/>
<Button
android:id="#+id/show_answer_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="#string/show_answer_button"/>
</LinearLayout>
LandLayout - activity_quiz
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:orientation="vertical">
<TextView
android:id="#+id/question_text_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:padding="24dp"/>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal|center_vertical"
android:orientation="vertical">
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal|center_vertical"
android:orientation="horizontal">
<Button
android:id="#+id/trueButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/trueButton"/>
<Button
android:id="#+id/falseButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/falseButton"/>
</LinearLayout>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|center"
android:text="#string/cheat_button"/>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal|center_vertical"
android:orientation="horizontal">
<ImageButton
android:id="#+id/previousButton"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:contentDescription="#string/previousButton"
android:src="#drawable/arrow_left"/>
<ImageButton
android:id="#+id/nextButton"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="center_horizontal|center_vertical"
android:contentDescription="#string/nextButton"
android:src="#drawable/arrow_right"/>
</LinearLayout>
</LinearLayout>
</FrameLayout>
vertical layout- activity_quiz
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:orientation="vertical">
<TextView
android:id="#+id/question_text_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="24dp"/>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal">
<Button
android:id="#+id/trueButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/trueButton"/>
<Button
android:id="#+id/falseButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/falseButton"/>
</LinearLayout>
<Button
android:id="#+id/cheatButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/cheat_button"/>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal">
<ImageButton
android:id="#+id/previousButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:contentDescription="#string/previousButton"
android:src="#drawable/arrow_left"/>
<ImageButton
android:id="#+id/nextButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:contentDescription="#string/nextButton"
android:src="#drawable/arrow_right"/>
</LinearLayout>
</LinearLayout>
Strings..
<resources>
<string name="app_name">RyanHull_Quiz</string>
<string name="action_settings">Settings</string>
<string name="trueButton">True</string>
<string name="falseButton">False</string>
<string name="nextButton">Next</string>
<string name="previousButton">Previous</string>
<string name="cheat_button">Cheat!</string>
<string name="correct_toast">Correct! :)</string>
<string name="incorrect_toast">Incorrect! :(</string>"
<string name="question_oceans">The Pacific Ocean is larger than the Atlantic Ocean.</string>
<string name="question_mideast">The Suez Canal connects the Red Sea and the Indian Ocean.</string>
<string name="question_africa">The source of the Nile River is in Egypt.</string>
<string name="question_americas">The Amazon River is the longest river in the Americas.</string>
<string name="question_asia">Lake Baikal is the world\'s oldest and deepest freshwater lake.</string>
<string name="warning_text">Are you sure you want to do this??</string>
<string name="show_answer_button">Show Answer</string>
<string name="judgment_toast">Cheating is Wrong 8/</string>
<string name="title_activity_cheat">Cheat</string>
and finally manifest....
<?xml version="1.0" encoding="utf-8"?>
<manifest package="com.example.ryan.ryans_quiz"
xmlns:android="http://schemas.android.com/apk/res/android">
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity android:name=".QuizActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
<!--
ATTENTION: This was auto-generated to add Google Play services to your project for
App Indexing. See https://g.co/AppIndexing/AndroidStudio for more information.
-->
<meta-data
android:name="com.google.android.gms.version"
android:value="#integer/google_play_services_version"/>
<activity
android:name=".CheatActivity"
android:label="#string/title_activity_cheat"
android:theme="#style/AppTheme.NoActionBar">
</activity>
</application>
EDIT: its not a matter of me know what the exception is.. More of the matter of find where and why...

The lookup is failing for mCheatButton because you forgot to assign it an id in the landscape version of the activity_quiz.xml layout file.
When you then try to set a ClickListener on a null object that is where the NullPointerException is coming from.

when you rotate the device,the QuizActivity will destroy and then call onCreate，but your LandLayout file has no Button called 'cheatButton',so findViewById(R.id.cheatButton) will return null to mCheatButton, it can not call any method.

You haven't assigned any id to cheat button in LandLayout - activity_quiz
Change
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|center"
android:text="#string/cheat_button"/>
to
<Button
android:id="#+id/cheatButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|center"
android:text="#string/cheat_button"/>

NullPointerException MainFragment facebook login

Pretty new to this. I am trying to make a simple facebook login app that once logged in show a few basic user details. When I try to run the app I get the message 'Unfortunately FacebookTest has stopped'. I seem to be getting a NullPointerException but can't for the life of me work out why. Here is my logcat output:
03-25 12:01:16.850 919-919/com.example.robert.facebooktest E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.robert.facebooktest, PID: 919
java.lang.NullPointerException
at com.example.robert.facebooktest.MainFragment$2.onCompleted(MainFragment.java:87)
at com.facebook.Request$1.onCompleted(Request.java:283)
at com.facebook.Request$4.run(Request.java:1668)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
My code is as follows:
MainActivity.java
package com.example.robert.facebooktest;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
public class MainActivity extends FragmentActivity {
private MainFragment mainFragment;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (savedInstanceState == null) {
// Add the fragment on initial activity setup
mainFragment = new MainFragment();
getSupportFragmentManager().beginTransaction()
.add(android.R.id.content, mainFragment).commit();
} else {
// Or set the fragment from restored state info
mainFragment = (MainFragment) getSupportFragmentManager()
.findFragmentById(android.R.id.content);
}
}
}
MainFragment.java
package com.example.robert.facebooktest;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import com.facebook.Request;
import com.facebook.Response;
import com.facebook.Session;
import com.facebook.SessionState;
import com.facebook.UiLifecycleHelper;
import com.facebook.model.GraphUser;
import com.facebook.widget.LoginButton;
public class MainFragment extends Fragment {
TextView name;
TextView location;
TextView gender;
private static final String TAG = "MainFragment";
// Create, automatically open (if applicable), save, and restore the
// Active Session in a way that is similar to Android UI lifecycles.
private UiLifecycleHelper uiHelper;
private View otherView;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// To maintain FB Login session
uiHelper = new UiLifecycleHelper(getActivity(), callback);
uiHelper.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.activity_main, container, false);
// Looks for Login button
LoginButton authButton = (LoginButton) view.findViewById(R.id.authButton);
authButton.setFragment(this);
// Set View that should be visible after log-in invisible initially
otherView = view.findViewById(R.id.other_views);
otherView.setVisibility(View.GONE);
//authButton.setReadPermissions(Arrays.asList("user_likes", "user_status","email","user_birthday"));
return view;
}
// Called when session changes
private Session.StatusCallback callback = new Session.StatusCallback() {
#Override
public void call(Session session, SessionState state,
Exception exception) {
onSessionStateChange(session, state, exception);
}
};
// When session is changed, this method is called from callback method
private void onSessionStateChange(Session session, SessionState state,Exception exception) {
final TextView name = (TextView) getView().findViewById(R.id.name);
final TextView gender = (TextView) getView().findViewById(R.id.gender);
final TextView location = (TextView) getView().findViewById(R.id.location);
if (state.isOpened()) {
Log.i(TAG, "Logged in...");
// make request to the /me API to get Graph user
Request.newMeRequest(session, new Request.GraphUserCallback() {
// callback after Graph API response with user
// object
#Override
public void onCompleted(GraphUser user, Response response) {
if (user != null) {
// Set view visibility to true
otherView.setVisibility(View.VISIBLE);
// Set User name
name.setText("Hello " + user.getName());
// Set Gender
gender.setText("Your Gender: "
+ user.getProperty("gender").toString());
location.setText("Your Current Location: "
+ user.getLocation().getProperty("name").toString());
}else{
return;
}
}
}).executeAsync();
} else if (state.isClosed()) {
Log.i(TAG, "Logged out...");
otherView.setVisibility(View.GONE);
}
}
#Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
uiHelper.onActivityResult(requestCode, resultCode, data);
Log.i(TAG, "OnActivityResult...");
}
#Override
public void onResume() {
super.onResume();
uiHelper.onResume();
}
#Override
public void onPause() {
super.onPause();
uiHelper.onPause();
}
#Override
public void onDestroy() {
super.onDestroy();
uiHelper.onDestroy();
}
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
uiHelper.onSaveInstanceState(outState);
}
}
activity_main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#drawable/bg_gradient"
android:orientation="vertical"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.example.robert.facebooktest.MainActivity" >
<ImageView
android:layout_width="300dp"
android:layout_height="100dp"
android:layout_gravity="center"
android:src="#drawable/voyager_logo" />
<LinearLayout
android:id="#+id/other_views"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:orientation="vertical"
android:padding="5dp" >
<TextView
android:id="#+id/name"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="10dip"
android:gravity="left"
android:text="Name"
android:textColor="#color/white"
android:textSize="30dp" />
<TextView
android:id="#+id/gender"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="10dip"
android:gravity="left"
android:text="Gender"
android:textColor="#color/white"
android:textSize="15dp" />
<TextView
android:id="#+id/location"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="10dip"
android:gravity="left"
android:text="Location"
android:textColor="#color/white"
android:textSize="15dp" />
</LinearLayout>
<LinearLayout
android:id="#+id/fb_view"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:gravity="bottom"
android:orientation="vertical"
android:padding="5dp" >
<com.facebook.widget.LoginButton
android:id="#+id/authButton"
android:layout_width="250dp"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_marginTop="30dp" />
</LinearLayout>

Which is the line no 87 exactly? Somewhere in onCompleted()