Develop Reference

Getting java.lang.NullPointerException when trying to launch activity from presenter using view interface

I am trying to change from one screen to another after a user has signed up. The user is created but I get a java.lang.NullPointerException when I call the view interface from the presenter.
Here is the part in the presenter that creates the user and prompts the change to a login screen.
public void signUp() {
postUserUseCase.setWyat_user(user);
subscription = postUserUseCase
.execute()
.subscribeOn(rx.schedulers.Schedulers.newThread())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Subscriber<User>() {
#Override
public void onCompleted() {
Log.d("complete","complete");
signUpView.showLoginScreen();
}
#Override
public void onError(Throwable e) {
}
#Override
public void onNext(User user) {
Log.d("next",user.getEmail());
}
});
}
SignupActivity implements the view interface's showLoginScreen method.
public class SignUpActivity extends AppCompatActivity implements SignUpView {
#Override
public void showLoginScreen() {
Intent loginIntent = new Intent(this,LoginActivity.class);
startActivity(loginIntent);
}
}
The user is created but I get a null pointer onCompleted.
EDIT:
This is different from What is a NullPointerException, and how do I fix it? because if I did the initializing of an interface I get a whole class with the methods that my activity will override. This is a view interface not a variable or a class.I just want to call on method.
EDIT 2: Logcat for the error.
01-14 14:41:49.359 28309-28309/com.wyat.wyat E/AndroidRuntime: FATAL
EXCEPTION: main
java.lang.IllegalStateException: Fatal Exception thrown on
Scheduler.Worker thread.
at rx.internal.schedulers.ScheduledAction.run(ScheduledAction.java:62)
at android.os.Handler.handleCallback(Handler.java:605)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4517)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:995)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:762)
at dalvik.system.NativeStart.main(Native Method)
Caused by: rx.exceptions.OnCompletedFailedException
at rx.observers.SafeSubscriber.onCompleted(SafeSubscriber.java:90)
at rx.internal.operators.OperatorObserveOn$ObserveOnSubscriber.checkTerminated(OperatorObserveOn.java:272)
at rx.internal.operators.OperatorObserveOn$ObserveOnSubscriber.call(OperatorObserveOn.java:207)
at rx.internal.schedulers.ScheduledAction.run(ScheduledAction.java:55)
at android.os.Handler.handleCallback(Handler.java:605) 
at android.os.Handler.dispatchMessage(Handler.java:92) 
at android.os.Looper.loop(Looper.java:137) 
at android.app.ActivityThread.main(ActivityThread.java:4517) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:511) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:995) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:762) 
at dalvik.system.NativeStart.main(Native Method) 
Caused by: java.lang.NullPointerException
at com.wyat.wyat.accounts.presenters.SignUpPresenter$1.onCompleted(SignUpPresenter.java:92)
at rx.observers.SafeSubscriber.onCompleted(SafeSubscriber.java:84)
at rx.internal.operators.OperatorObserveOn$ObserveOnSubscriber.checkTerminated(OperatorObserveOn.java:272) 
at rx.internal.operators.OperatorObserveOn$ObserveOnSubscriber.call(OperatorObserveOn.java:207) 
at rx.internal.schedulers.ScheduledAction.run(ScheduledAction.java:55) 
at android.os.Handler.handleCallback(Handler.java:605) 
at android.os.Handler.dispatchMessage(Handler.java:92) 
at android.os.Looper.loop(Looper.java:137) 
at android.app.ActivityThread.main(ActivityThread.java:4517) 
at java.lang.reflect.Method.invokeNative(Native Method)

How can I change the volume properly?

I have been stuck on this for way too long (4 hours yesterday, 3 hours today!) now. In my main menu screen, I have a mute button. I want it to call a method in my background service, which mutes all of the MediaPlayer audio that would be played in the background of my game.
Full code here
Here is something that might be causing the issue:
I am getting the error whenever the audio plays (which plays fine):
QCMediaPlayer mediaplayer NOT present
E/MediaPlayer﹕ Should have subtitle controller already set
package com.example.USERNAME.buttonsmasher;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.media.MediaPlayer;
import android.os.CountDownTimer;
import android.os.IBinder;
import android.support.annotation.Nullable;
import android.util.Log;
public class TwentySeconds extends Service {
static MediaPlayer ten;
static MediaPlayer three;
final String TAG = "MyCountdown";
static CountDownTimer cdt;
double millisUntilFinishedRounded;
#Nullable
#Override
public IBinder onBind(Intent intent) {
return null;
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
Context context = this;
three = MediaPlayer.create(TwentySeconds.this, R.raw.threetwoone);
ten = MediaPlayer.create(TwentySeconds.this, R.raw.tenmoreseconds);
// ten = MediaPlayer.create(TwentySeconds.this, R.raw.tenmoreseconds);
// three = MediaPlayer.create(TwentySeconds.this, R.raw.threetwoone);
Log.v(TAG, "In start command");
cdt = new CountDownTimer(20000, 1000) {
#Override
public void onTick(long millisUntilFinished) {
Log.v(TAG, millisUntilFinished + "left");
millisUntilFinishedRounded = (millisUntilFinished / 1000) * 1000;
if (millisUntilFinishedRounded == 10000) { //TEN SECONDS
// ten = MediaPlayer.create(TwentySeconds.this, R.raw.tenmoreseconds);
// while(ten == null){
ten = MediaPlayer.create(TwentySeconds.this, R.raw.tenmoreseconds);
// }
ten.start();
}
if (millisUntilFinishedRounded == 3000) {
/* Context context = this;
three = MediaPlayer.create(TwentySeconds.this, R.raw.threetwoone);
*/
// while(three == null){
three = MediaPlayer.create(TwentySeconds.this, R.raw.tenmoreseconds);
//}
three.start();
}
}
#Override
public void onFinish() {
Log.v(TAG, "Finished");
Intent intent = new Intent(TwentySeconds.this, GameOver.class);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
Log.v(TAG, "About to start activity");
startActivity(intent);
}
};
cdt.start();
return START_STICKY;
}
public static void stopTimer() {
cdt.cancel();
}
public static void myMute() {
ten.setVolume(0, 0);
three.setVolume(0, 0);
}
public static void unMute() {
ten.setVolume(1, 1);
three.setVolume(1, 1);
}
#Override
public void onDestroy() {
stopSelf();
super.onDestroy();
}
}
_______________________________________________________________________________________________________________________________
Here is the method in Main_Menu (x starts as zero)
if ((x%2) == 0) { //If it's even
TwentySeconds.unMute();
Toast.makeText(Main_Menu.this, "UNMUTED", Toast.LENGTH_SHORT).show();
x++;
} else { //If its odd
TwentySeconds.myMute();
Toast.makeText(Main_Menu.this, "MUTED", Toast.LENGTH_SHORT).show();
x++;
}
__________________________________________________________________
Here is the stack trace:
java.lang.IllegalStateException: Could not execute method of the activity
at android.view.View$1.onClick(View.java:3842)
at android.view.View.performClick(View.java:4457)
at android.view.View$PerformClick.run(View.java:18491)
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:5272)
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:883)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at android.view.View$1.onClick(View.java:3837)
at android.view.View.performClick(View.java:4457)
at android.view.View$PerformClick.run(View.java:18491)
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:5272)
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:883)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.example.USERNAME.buttonsmasher.TwentySeconds.myMute(TwentySeconds.java:106)
at com.example.USERNAME.buttonsmasher.Main_Menu.mute(Main_Menu.java:103)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at android.view.View$1.onClick(View.java:3837)
at android.view.View.performClick(View.java:4457)
at android.view.View$PerformClick.run(View.java:18491)
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:5272)
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:883)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)
at dalvik.system.NativeStart.main(Native Method)
I would really appreciate any feedback (positive or negative)!
Let me know if you need any thing else. Thanks so much for everything, I hope I can solve this issue... :)

how to find null pointer exception with logcat

I'm trying to build a small app that takes a data file in external storage and emails it. I keep getting 'null pointer exceptions' right away in logcat and then my app dies. I can't seem to locate my exception and I am wondering if there is a way to determine the line of code that is causing this. I have the MainActivity class and then a class called SendData- the code is below. I'm new at this so any help would be greatly appreciated- thank you.
private static final String TAG = "MainActivity_ErrorLog";
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
#Override
public boolean onCreateOptionsMenu(Menu menu)
{
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
// Create the getData intent
Intent intentgetData = new Intent(MainActivity.this, SendData.class);
public void onStart()
{
{
try
{
File sd = Environment.getExternalStorageDirectory();
File data = Environment.getDataDirectory();
if (sd.canWrite())
{
// verify the paths
String currentDBPath = "TLC_COMMON/database.db";
String backupDBPath = "database.db";
File currentDB = new File(data, currentDBPath);
File backupDB = new File(sd, backupDBPath);
if (currentDB.exists())
{
FileChannel src = new FileInputStream(currentDB).getChannel();
FileChannel dst = new FileOutputStream(backupDB).getChannel();
dst.transferFrom(src, 0, src.size());
src.close();
dst.close();
}
}
}
catch (Exception e)
{
// change the V below to E when complete
Log.v(TAG,"ERROR: Database file not created");
}
startActivity(intentgetData);
}
}
}
--new class
public class SendData extends Activity
{
private static final String TAG = "MainActivity";
/* Checks if external storage is available to read */
public boolean isExternalStorageReadable()
{
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state) ||
Environment.MEDIA_MOUNTED_READ_ONLY.equals(state))
{
return true;
}
return false;
}
/** Called when the user clicks the Send My Data button */
public SendData(View view)
{
// Send data by email
{
File root = Environment.getExternalStorageDirectory();
// verify it is saving as this file name; also path in previous class
String fileName = "database.db";
if (root.canWrite())
{
File attachment = new File(root, fileName);
Intent email = new Intent(Intent.ACTION_SENDTO);
email.putExtra(android.content.Intent.EXTRA_SUBJECT, "Exercise data");
email.putExtra(android.content.Intent.EXTRA_EMAIL, new String[]{"test#gmail.com"});
// is the Uri necessary?
email.putExtra(android.content.Intent.EXTRA_TEXT, Uri.fromFile(attachment));
// look at this VVV
startActivity(Intent.createChooser(email, "Send the data via Email"));}
else
{
// Change the V below to E when complete
Log.v(TAG, "Email send failed");
}
}
}
public void finish()
{
}
}
11-13 13:29:37.343: W/dalvikvm(3319): threadid=1: thread exiting with uncaught exception (group=0x418e3300)
11-13 13:29:37.343: E/AndroidRuntime(3319): FATAL EXCEPTION: main
11-13 13:29:37.343: E/AndroidRuntime(3319): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.va.datasender/com.example.va.datasender.MainActivity}: java.lang.NullPointerException
11-13 13:29:37.343: E/AndroidRuntime(3319): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1983)
11-13 13:29:37.343: E/AndroidRuntime(3319): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
11-13 13:29:37.343: E/AndroidRuntime(3319): at android.app.ActivityThread.access$600(ActivityThread.java:130)
11-13 13:29:37.343: E/AndroidRuntime(3319): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
11-13 13:29:37.343: E/AndroidRuntime(3319): at android.os.Handler.dispatchMessage(Handler.java:99)
11-13 13:29:37.343: E/AndroidRuntime(3319): at android.os.Looper.loop(Looper.java:137)
11-13 13:29:37.343: E/AndroidRuntime(3319): at android.app.ActivityThread.main(ActivityThread.java:4745)
11-13 13:29:37.343: E/AndroidRuntime(3319): at java.lang.reflect.Method.invokeNative(Native Method)
11-13 13:29:37.343: E/AndroidRuntime(3319): at java.lang.reflect.Method.invoke(Method.java:511)
11-13 13:29:37.343: E/AndroidRuntime(3319): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
11-13 13:29:37.343: E/AndroidRuntime(3319): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
11-13 13:29:37.343: E/AndroidRuntime(3319): at dalvik.system.NativeStart.main(Native Method)
11-13 13:29:37.343: E/AndroidRuntime(3319): Caused by: java.lang.NullPointerException
11-13 13:29:37.343: E/AndroidRuntime(3319): at android.content.ContextWrapper.getPackageName(ContextWrapper.java:127)
11-13 13:29:37.343: E/AndroidRuntime(3319): at android.content.ComponentName.<init>(ComponentName.java:75)
11-13 13:29:37.343: E/AndroidRuntime(3319): at android.content.Intent.<init>(Intent.java:3301)
11-13 13:29:37.343: E/AndroidRuntime(3319): at com.example.va.datasender.MainActivity.<init>(MainActivity.java:36)
11-13 13:29:37.343: E/AndroidRuntime(3319): at java.lang.Class.newInstanceImpl(Native Method)
11-13 13:29:37.343: E/AndroidRuntime(3319): at java.lang.Class.newInstance(Class.java:1319)
11-13 13:29:37.343: E/AndroidRuntime(3319): at android.app.Instrumentation.newActivity(Instrumentation.java:1053)
11-13 13:29:37.343: E/AndroidRuntime(3319): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1974)
11-13 13:29:37.343: E/AndroidRuntime(3319): ... 11 more

Find the lowest "Caused by" and continue down until you reach a line from your code:
Caused by: java.lang.NullPointerException
at android.content.ContextWrapper.getPackageName(ContextWrapper.java:127)
at android.content.ComponentName.<init>(ComponentName.java:75)
at android.content.Intent.<init>(Intent.java:3301)
at com.example.va.datasender.MainActivity.<init>(MainActivity.java:36)
The <init> means you are doing something as a class variable or inside a constructor before the Activity has a valid Context... But the specific problem is on line 36.
I would guess that you are trying to create an Intent with this. Initialize your Intent inside onCreate() instead.
Found it. Change this:
// Create the getData intent
Intent intentgetData = new Intent(MainActivity.this, SendData.class);
to:
Intent intentgetData;
and inside onCreate() (or onStart() just before calling startActivity()) add:
intentgetData = new Intent(MainActivity.this, SendData.class);

Your problem comes from line 36 on your MainActivity. Check there for the problem.
11-13 13:29:37.343: E/AndroidRuntime(3319): at com.example.va.datasender.MainActivity.<init>(MainActivity.java:36)

The exeption from line number 36: at com.example.va.datasender.MainActivity.<init>(MainActivity.java:36).

Since the error log also shows android.content.Intent.<init> after the MainActivity.java:36, I would check the value for the first parameter in the following line, when instantiating intentgetData:
Intent intentgetData = new Intent(MainActivity.this, SendData.class);
Instead of having the instatiation done there, try doing it in the onStart() method just before calling startActivity(intentgetData);:
Intent intentgetData = new Intent(MainActivity.this, SendData.class);
startActivity(intentgetData);

Code keeps thowing a NPE, cannot find the cause

i cannot find the null pointer exception in my code, i was wondering if anyone could help me find what is giving an error.
code:
package com.dingle.ubat;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.os.PowerManager;
import android.view.Display;
import android.view.MotionEvent;
import android.widget.Toast;
public class UltraBrightAndroidTorchActivity extends Activity {
/** Called when the activity is first created. */
PowerManager pm;
PowerManager.WakeLock wl;
public boolean flash = false;
public boolean enableFlash = false;
public boolean dimDisplay = false;
Display display = getWindowManager().getDefaultDisplay();
public int windowWidth = display.getWidth();
public int windowHeight = display.getHeight();
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
wl = pm.newWakeLock(PowerManager.FULL_WAKE_LOCK, "My Tag");
flash = this.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA_FLASH);
if(flash == true && enableFlash == true){
try {
DroidLED led = new DroidLED();
led.enable(!led.isEnabled());
}
catch(Exception e) {
Toast.makeText(this, "Error interacting with LED.", Toast.LENGTH_SHORT).show();
throw new RuntimeException(e);
} }
wl.acquire();
}
#Override
public boolean onTouchEvent(MotionEvent event) {
//int tx = (int) event.getRawX();
int ty = (int) event.getRawY();
if (ty <= (windowHeight/2)){
dimDisplay = !dimDisplay;
}
if (ty >= (windowHeight/2)){
enableFlash = !enableFlash;
}
return super.onTouchEvent(event);
}
#Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
wl.release();
}
#Override
protected void onNewIntent(Intent intent) {
// TODO Auto-generated method stub
super.onNewIntent(intent);
wl.release();
}
#Override
protected void onPause() {
// TODO Auto-generated method stub
super.onPause();
wl.release();
}
#Override
protected void onStop() {
// TODO Auto-generated method stub
super.onStop();
wl.release();
}
}
Error list:
12-10 20:40:42.224: W/dalvikvm(274): threadid=3: thread exiting with uncaught exception (group=0x4001b188)
12-10 20:40:42.232: E/AndroidRuntime(274): Uncaught handler: thread main exiting due to uncaught exception
12-10 20:40:42.282: E/AndroidRuntime(274): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.dingle.ubat/com.dingle.ubat.UltraBrightAndroidTorchActivity}: java.lang.NullPointerException
12-10 20:40:42.282: E/AndroidRuntime(274): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2417)
12-10 20:40:42.282: E/AndroidRuntime(274): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2512)
12-10 20:40:42.282: E/AndroidRuntime(274): at android.app.ActivityThread.access$2200(ActivityThread.java:119)
12-10 20:40:42.282: E/AndroidRuntime(274): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1863)
12-10 20:40:42.282: E/AndroidRuntime(274): at android.os.Handler.dispatchMessage(Handler.java:99)
12-10 20:40:42.282: E/AndroidRuntime(274): at android.os.Looper.loop(Looper.java:123)
12-10 20:40:42.282: E/AndroidRuntime(274): at android.app.ActivityThread.main(ActivityThread.java:4363)
12-10 20:40:42.282: E/AndroidRuntime(274): at java.lang.reflect.Method.invokeNative(Native Method)
12-10 20:40:42.282: E/AndroidRuntime(274): at java.lang.reflect.Method.invoke(Method.java:521)
12-10 20:40:42.282: E/AndroidRuntime(274): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
12-10 20:40:42.282: E/AndroidRuntime(274): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
12-10 20:40:42.282: E/AndroidRuntime(274): at dalvik.system.NativeStart.main(Native Method)
12-10 20:40:42.282: E/AndroidRuntime(274): Caused by: java.lang.NullPointerException
12-10 20:40:42.282: E/AndroidRuntime(274): at com.dingle.ubat.UltraBrightAndroidTorchActivity.<init>(UltraBrightAndroidTorchActivity.java:20)
12-10 20:40:42.282: E/AndroidRuntime(274): at java.lang.Class.newInstanceImpl(Native Method)
12-10 20:40:42.282: E/AndroidRuntime(274): at java.lang.Class.newInstance(Class.java:1479)
12-10 20:40:42.282: E/AndroidRuntime(274): at android.app.Instrumentation.newActivity(Instrumentation.java:1021)
12-10 20:40:42.282: E/AndroidRuntime(274): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2409)
12-10 20:40:42.282: E/AndroidRuntime(274): ... 11 more
any help and criticism is greatly appreciated
code is being compiled for android 2.1. code is a basic, crappily coded torch app.
thanx

The code is bailing out on one of these two lines:
Display display = getWindowManager().getDefaultDisplay();
public int windowWidth = display.getWidth();
Either getWindowManager() is returning a null and that first initializer will fail, or getDefaultDisplay() is, and the second one will.
You should probably move these initializations to the onCreate handler. Having them at instance initialization sounds a bit risky - the activity's "environment" might not be completely set up yet at that point.
(And check the return values.)

Activity is full available only after it has been created. This line does not do the intended purpose:
 Display display = getWindowManager().getDefaultDisplay();
Move this line and subsequent ones inside onCreate method.

Android program problem, NullPointerExc

Well, my program keeps giveing me a null point exception and I don't know why? I know it has something to do with the lvl variable, but I don't know what? What can I do to fix this problem?
Logcat:
03-18 16:14:55.852: ERROR/AndroidRuntime(277): FATAL EXCEPTION: main
03-18 16:14:55.852: ERROR/AndroidRuntime(277): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.games.think/com.games.think.Think}: java.lang.NullPointerException
03-18 16:14:55.852: ERROR/AndroidRuntime(277): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
03-18 16:14:55.852: ERROR/AndroidRuntime(277): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
03-18 16:14:55.852: ERROR/AndroidRuntime(277): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
03-18 16:14:55.852: ERROR/AndroidRuntime(277): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
03-18 16:14:55.852: ERROR/AndroidRuntime(277): at android.os.Handler.dispatchMessage(Handler.java:99)
03-18 16:14:55.852: ERROR/AndroidRuntime(277): at android.os.Looper.loop(Looper.java:123)
03-18 16:14:55.852: ERROR/AndroidRuntime(277): at android.app.ActivityThread.main(ActivityThread.java:4627)
03-18 16:14:55.852: ERROR/AndroidRuntime(277): at java.lang.reflect.Method.invokeNative(Native Method)
03-18 16:14:55.852: ERROR/AndroidRuntime(277): at java.lang.reflect.Method.invoke(Method.java:521)
03-18 16:14:55.852: ERROR/AndroidRuntime(277): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
03-18 16:14:55.852: ERROR/AndroidRuntime(277): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
03-18 16:14:55.852: ERROR/AndroidRuntime(277): at dalvik.system.NativeStart.main(Native Method)
03-18 16:14:55.852: ERROR/AndroidRuntime(277): Caused by: java.lang.NullPointerException
03-18 16:14:55.852: ERROR/AndroidRuntime(277): at com.games.think.Think.onCreate(Think.java:38)
03-18 16:14:55.852: ERROR/AndroidRuntime(277): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
03-18 16:14:55.852: ERROR/AndroidRuntime(277): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
03-18 16:14:55.852: ERROR/AndroidRuntime(277): ... 11 more
Here is some of my code:
package com.games.think;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.RadioButton;
public class Think extends Activity implements OnClickListener{
int question = 1, lvl;
/** Called when the activity is first created. */
RadioButton lvl1;
RadioButton lvl2;
RadioButton lvl3;
RadioButton lvl4;
RadioButton lvl5;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button play = (Button)findViewById(R.id.play);
play.setOnClickListener(this);
Button level = (Button)findViewById(R.id.level);
level.setOnClickListener(this);
Button exit = (Button)findViewById(R.id.exit);
exit.setOnClickListener(this);
Button setLevel = (Button)findViewById(R.id.setLevel);
setLevel.setOnClickListener(this);
lvl1 = (RadioButton)findViewById(R.id.lvl1);
lvl2 = (RadioButton)findViewById(R.id.lvl2);
lvl3 = (RadioButton)findViewById(R.id.lvl3);
lvl4 = (RadioButton)findViewById(R.id.lvl4);
lvl5 = (RadioButton)findViewById(R.id.lvl5);
lvl = getLevel();
if(lvl == -1) {
lvl=getLevel();
}
}
#SuppressWarnings("null")
private int getLevel() {
String FILENAME = "think_level";
FileInputStream fis;
byte[] buffer = new byte[1000];
try {
fis = openFileInput(FILENAME);
} catch (FileNotFoundException e) {
setLevel("1");
return -1;
}
try {
fis.read(buffer,0,1000);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
fis.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
String level = buffer.toString();
int iLevel = Integer.valueOf(level);
return iLevel;
}
private void setLevel(String level) {
String FILENAME = "think_level";
String string = level;
FileOutputStream fos;
try {
fos = openFileOutput(FILENAME, Context.MODE_PRIVATE);
fos.write(string.getBytes());
fos.close();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
#Override
public void onClick(View v) {
switch( v.getId()){
case R.id.play:
setContentView(R.layout.play);
setQuestion();
case R.id.level:
setContentView(R.layout.level);
switch(getLevel()) {
case 1:
lvl1.setChecked(true);
case 2:
lvl2.setChecked(true);
case 3:
lvl3.setChecked(true);
case 4:
lvl4.setChecked(true);
case 5:
lvl5.setChecked(true);
}
case R.id.setLevel:
if(lvl1.isChecked()) {
setLevel("1");
}
if(lvl2.isChecked()) {
setLevel("2");
}
if(lvl3.isChecked()) {
setLevel("3");
}
if(lvl4.isChecked()) {
setLevel("4");
}
if(lvl5.isChecked()) {
setLevel("5");
}
}
}
private void setQuestion() {
}
}

Check if the button with id "setLevel" is in your main.xml. If it is somewhere else, you can not find it like this:
Button setLevel = (Button)findViewById(R.id.setLevel);
But you need an inflater.

If iunderstand this is 37-38 lines
Button setLevel = (Button)findViewById(R.id.setLevel);
setLevel.setOnClickListener(this);
Seems like setLevel is null. Is button with id setLevel described in xml layout ?

Button setLevel = (Button)findViewById(R.id.setLevel);
This line is not returning an object. Make sure you have the id right and that there is a button registered with it.