title: Why is using TextView to update int value and display it giving me a crash?
body: <p>Im trying to develop a text adventure for android. Already found a subtle way to change 'pages' without creating new Activity.</p>
  
  <p>Now I was trying to include permanent int values on each of my layouts that would get updated immediately when changed.</p>
  
  <p>I.e. gold/health values. Depending on the choice of player ingame, it would:
  - change the layout to the corresponding page
  - change int value of Gold +10, health -1</p>
  
  <p>I developed this code in the mainactivity class:</p>
  
  <pre><code>package com.example.textadventure;
  
  import android.app.Activity;
  import android.os.Bundle;
  import android.view.View;
  import android.widget.TextView;
  
  public class MainActivity extends Activity {
  
      private int int1 = 1;
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);
      }
  
      public void changelayout1(View view){
          setContentView(R.layout.activity_main2);
          int1 += 1;
      }
      public void changelayout2(View view){
          setContentView(R.layout.activity_main);
          int1 += 1;
      }
      public void changelayout3(View view){
          setContentView(R.layout.activity_main3);
          int1 += 1;
      }
  
  
  
      public void onResume() {
          super.onResume();
          TextView textView = (TextView) this.findViewById(R.id.mytextview1);
          textView.setText(String.valueOf(int1));
      }
  
  
  
  }
  </code></pre>
  
  <p><strong>with the following result:</strong></p>
  
  <p>My LogCat</p>
  
  <pre><code>04-19 16:09:57.446: E/Trace(3204): error opening trace file: No such file or directory (2)
  04-19 16:09:59.016: D/AndroidRuntime(3204): Shutting down VM
  04-19 16:09:59.016: W/dalvikvm(3204): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
  04-19 16:09:59.036: E/AndroidRuntime(3204): FATAL EXCEPTION: main
  04-19 16:09:59.036: E/AndroidRuntime(3204): java.lang.RuntimeException: Unable to resume activity {com.example.textadventure/com.example.textadventure.MainActivity}: java.lang.NullPointerException
  04-19 16:09:59.036: E/AndroidRuntime(3204):     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2742)
  04-19 16:09:59.036: E/AndroidRuntime(3204):     at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2771)
  04-19 16:09:59.036: E/AndroidRuntime(3204):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2235)
  04-19 16:09:59.036: E/AndroidRuntime(3204):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
  04-19 16:09:59.036: E/AndroidRuntime(3204):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
  04-19 16:09:59.036: E/AndroidRuntime(3204):     at android.os.Handler.dispatchMessage(Handler.java:99)
  04-19 16:09:59.036: E/AndroidRuntime(3204):     at android.os.Looper.loop(Looper.java:137)
  04-19 16:09:59.036: E/AndroidRuntime(3204):     at android.app.ActivityThread.main(ActivityThread.java:5041)
  04-19 16:09:59.036: E/AndroidRuntime(3204):     at java.lang.reflect.Method.invokeNative(Native Method)
  04-19 16:09:59.036: E/AndroidRuntime(3204):     at java.lang.reflect.Method.invoke(Method.java:511)
  04-19 16:09:59.036: E/AndroidRuntime(3204):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
  04-19 16:09:59.036: E/AndroidRuntime(3204):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
  04-19 16:09:59.036: E/AndroidRuntime(3204):     at dalvik.system.NativeStart.main(Native Method)
  04-19 16:09:59.036: E/AndroidRuntime(3204): Caused by: java.lang.NullPointerException
  04-19 16:09:59.036: E/AndroidRuntime(3204):     at com.example.textadventure.MainActivity.onResume(MainActivity.java:28)
  04-19 16:09:59.036: E/AndroidRuntime(3204):     at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1185)
  04-19 16:09:59.036: E/AndroidRuntime(3204):     at android.app.Activity.performResume(Activity.java:5182)
  04-19 16:09:59.036: E/AndroidRuntime(3204):     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2732)
  04-19 16:09:59.036: E/AndroidRuntime(3204):     ... 12 more
  04-19 16:10:02.386: I/Process(3204): Sending signal. PID: 3204 SIG: 9
  04-19 16:15:42.576: D/AndroidRuntime(3292): Shutting down VM
  04-19 16:15:42.586: W/dalvikvm(3292): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
  04-19 16:15:42.596: E/AndroidRuntime(3292): FATAL EXCEPTION: main
  04-19 16:15:42.596: E/AndroidRuntime(3292): java.lang.RuntimeException: Unable to resume activity {com.example.textadventure/com.example.textadventure.MainActivity}: java.lang.NullPointerException
  04-19 16:15:42.596: E/AndroidRuntime(3292):     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2742)
  04-19 16:15:42.596: E/AndroidRuntime(3292):     at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2771)
  04-19 16:15:42.596: E/AndroidRuntime(3292):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2235)
  04-19 16:15:42.596: E/AndroidRuntime(3292):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
  04-19 16:15:42.596: E/AndroidRuntime(3292):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
  04-19 16:15:42.596: E/AndroidRuntime(3292):     at android.os.Handler.dispatchMessage(Handler.java:99)
  04-19 16:15:42.596: E/AndroidRuntime(3292):     at android.os.Looper.loop(Looper.java:137)
  04-19 16:15:42.596: E/AndroidRuntime(3292):     at android.app.ActivityThread.main(ActivityThread.java:5041)
  04-19 16:15:42.596: E/AndroidRuntime(3292):     at java.lang.reflect.Method.invokeNative(Native Method)
  04-19 16:15:42.596: E/AndroidRuntime(3292):     at java.lang.reflect.Method.invoke(Method.java:511)
  04-19 16:15:42.596: E/AndroidRuntime(3292):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
  04-19 16:15:42.596: E/AndroidRuntime(3292):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
  04-19 16:15:42.596: E/AndroidRuntime(3292):     at dalvik.system.NativeStart.main(Native Method)
  04-19 16:15:42.596: E/AndroidRuntime(3292): Caused by: java.lang.NullPointerException
  04-19 16:15:42.596: E/AndroidRuntime(3292):     at com.example.textadventure.MainActivity.onResume(MainActivity.java:31)
  04-19 16:15:42.596: E/AndroidRuntime(3292):     at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1185)
  04-19 16:15:42.596: E/AndroidRuntime(3292):     at android.app.Activity.performResume(Activity.java:5182)
  04-19 16:15:42.596: E/AndroidRuntime(3292):     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2732)
  04-19 16:15:42.596: E/AndroidRuntime(3292):     ... 12 more
  04-19 16:18:00.358: E/Trace(3350): error opening trace file: No such file or directory (2)
  04-19 16:18:01.796: D/AndroidRuntime(3350): Shutting down VM
  04-19 16:18:01.810: W/dalvikvm(3350): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
  04-19 16:18:01.866: E/AndroidRuntime(3350): FATAL EXCEPTION: main
  04-19 16:18:01.866: E/AndroidRuntime(3350): java.lang.RuntimeException: Unable to resume activity {com.example.textadventure/com.example.textadventure.MainActivity}: java.lang.NullPointerException
  04-19 16:18:01.866: E/AndroidRuntime(3350):     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2742)
  04-19 16:18:01.866: E/AndroidRuntime(3350):     at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2771)
  04-19 16:18:01.866: E/AndroidRuntime(3350):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2235)
  04-19 16:18:01.866: E/AndroidRuntime(3350):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
  04-19 16:18:01.866: E/AndroidRuntime(3350):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
  04-19 16:18:01.866: E/AndroidRuntime(3350):     at android.os.Handler.dispatchMessage(Handler.java:99)
  04-19 16:18:01.866: E/AndroidRuntime(3350):     at android.os.Looper.loop(Looper.java:137)
  04-19 16:18:01.866: E/AndroidRuntime(3350):     at android.app.ActivityThread.main(ActivityThread.java:5041)
  04-19 16:18:01.866: E/AndroidRuntime(3350):     at java.lang.reflect.Method.invokeNative(Native Method)
  04-19 16:18:01.866: E/AndroidRuntime(3350):     at java.lang.reflect.Method.invoke(Method.java:511)
  04-19 16:18:01.866: E/AndroidRuntime(3350):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
  04-19 16:18:01.866: E/AndroidRuntime(3350):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
  04-19 16:18:01.866: E/AndroidRuntime(3350):     at dalvik.system.NativeStart.main(Native Method)
  04-19 16:18:01.866: E/AndroidRuntime(3350): Caused by: java.lang.NullPointerException
  04-19 16:18:01.866: E/AndroidRuntime(3350):     at com.example.textadventure.MainActivity.onResume(MainActivity.java:31)
  04-19 16:18:01.866: E/AndroidRuntime(3350):     at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1185)
  04-19 16:18:01.866: E/AndroidRuntime(3350):     at android.app.Activity.performResume(Activity.java:5182)
  04-19 16:18:01.866: E/AndroidRuntime(3350):     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2732)
  04-19 16:18:01.866: E/AndroidRuntime(3350):     ... 12 more
  04-19 16:22:06.477: E/Trace(3412): error opening trace file: No such file or directory (2)
  04-19 16:22:08.086: D/AndroidRuntime(3412): Shutting down VM
  04-19 16:22:08.116: W/dalvikvm(3412): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
  04-19 16:22:08.207: E/AndroidRuntime(3412): FATAL EXCEPTION: main
  04-19 16:22:08.207: E/AndroidRuntime(3412): java.lang.RuntimeException: Unable to resume activity {com.example.textadventure/com.example.textadventure.MainActivity}: java.lang.NullPointerException
  04-19 16:22:08.207: E/AndroidRuntime(3412):     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2742)
  04-19 16:22:08.207: E/AndroidRuntime(3412):     at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2771)
  04-19 16:22:08.207: E/AndroidRuntime(3412):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2235)
  04-19 16:22:08.207: E/AndroidRuntime(3412):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
  04-19 16:22:08.207: E/AndroidRuntime(3412):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
  04-19 16:22:08.207: E/AndroidRuntime(3412):     at android.os.Handler.dispatchMessage(Handler.java:99)
  04-19 16:22:08.207: E/AndroidRuntime(3412):     at android.os.Looper.loop(Looper.java:137)
  04-19 16:22:08.207: E/AndroidRuntime(3412):     at android.app.ActivityThread.main(ActivityThread.java:5041)
  04-19 16:22:08.207: E/AndroidRuntime(3412):     at java.lang.reflect.Method.invokeNative(Native Method)
  04-19 16:22:08.207: E/AndroidRuntime(3412):     at java.lang.reflect.Method.invoke(Method.java:511)
  04-19 16:22:08.207: E/AndroidRuntime(3412):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
  04-19 16:22:08.207: E/AndroidRuntime(3412):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
  04-19 16:22:08.207: E/AndroidRuntime(3412):     at dalvik.system.NativeStart.main(Native Method)
  04-19 16:22:08.207: E/AndroidRuntime(3412): Caused by: java.lang.NullPointerException
  04-19 16:22:08.207: E/AndroidRuntime(3412):     at com.example.textadventure.MainActivity.onResume(MainActivity.java:35)
  04-19 16:22:08.207: E/AndroidRuntime(3412):     at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1185)
  04-19 16:22:08.207: E/AndroidRuntime(3412):     at android.app.Activity.performResume(Activity.java:5182)
  04-19 16:22:08.207: E/AndroidRuntime(3412):     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2732)
  04-19 16:22:08.207: E/AndroidRuntime(3412):     ... 12 more
  04-19 16:22:10.786: I/Process(3412): Sending signal. PID: 3412 SIG: 9
  04-19 16:25:22.020: D/AndroidRuntime(3477): Shutting down VM
  04-19 16:25:22.020: W/dalvikvm(3477): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
  04-19 16:25:22.026: E/AndroidRuntime(3477): FATAL EXCEPTION: main
  04-19 16:25:22.026: E/AndroidRuntime(3477): java.lang.RuntimeException: Unable to resume activity {com.example.textadventure/com.example.textadventure.MainActivity}: java.lang.NullPointerException
  04-19 16:25:22.026: E/AndroidRuntime(3477):     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2742)
  04-19 16:25:22.026: E/AndroidRuntime(3477):     at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2771)
  04-19 16:25:22.026: E/AndroidRuntime(3477):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2235)
  04-19 16:25:22.026: E/AndroidRuntime(3477):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
  04-19 16:25:22.026: E/AndroidRuntime(3477):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
  04-19 16:25:22.026: E/AndroidRuntime(3477):     at android.os.Handler.dispatchMessage(Handler.java:99)
  04-19 16:25:22.026: E/AndroidRuntime(3477):     at android.os.Looper.loop(Looper.java:137)
  04-19 16:25:22.026: E/AndroidRuntime(3477):     at android.app.ActivityThread.main(ActivityThread.java:5041)
  04-19 16:25:22.026: E/AndroidRuntime(3477):     at java.lang.reflect.Method.invokeNative(Native Method)
  04-19 16:25:22.026: E/AndroidRuntime(3477):     at java.lang.reflect.Method.invoke(Method.java:511)
  04-19 16:25:22.026: E/AndroidRuntime(3477):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
  04-19 16:25:22.026: E/AndroidRuntime(3477):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
  04-19 16:25:22.026: E/AndroidRuntime(3477):     at dalvik.system.NativeStart.main(Native Method)
  04-19 16:25:22.026: E/AndroidRuntime(3477): Caused by: java.lang.NullPointerException
  04-19 16:25:22.026: E/AndroidRuntime(3477):     at com.example.textadventure.MainActivity.onResume(MainActivity.java:36)
  04-19 16:25:22.026: E/AndroidRuntime(3477):     at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1185)
  04-19 16:25:22.026: E/AndroidRuntime(3477):     at android.app.Activity.performResume(Activity.java:5182)
  04-19 16:25:22.026: E/AndroidRuntime(3477):     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2732)
  04-19 16:25:22.026: E/AndroidRuntime(3477):     ... 12 more
  </code></pre>
  
  <p>As i said i want to have something like this:</p>
  
  <p><a href="http://postimg.org/image/dy7g2ts6v/" rel="nofollow">http://postimg.org/image/dy7g2ts6v/</a></p>
  
  <p>I already know how to make buttons to switch layouts, but I can't display the integers without crash. :(</p>