Only the original thread that created a view hierarchy can touch its views. On android [duplicate]

Question

I'm only a beginner so please forgive me for asking possibly a stupid question

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I don't understand the meaning of Only the original thread that created a view hierarchy can touch its views.

Please can someone teach me why this error is occurring and how to solve this problem.

ThankYou

This is my class

public class MainActivity extends Activity {     TextView title;     Random   random  = new Random();     int      counter = 1;      @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.startup);         startingUp();     }      private void startingUp() {         Thread timer = new Thread() { //new thread                      public void run() {                 Boolean b = true;                 try {                     do {                         counter++;                         title();                         sleep(1000);                         title.clearComposingText();                      }                     while (b == true);                 } catch (IntruptedException e) {                     e.printStackTrace();                 }                 finally {                 }             };         };         timer.start();     }      public void title() {         title = (TextView) findViewById(R.id.tvTitle);         switch (random.nextInt(2)) {             case 0:                 title.setGravity(Gravity.RIGHT);                 break;             case 1:                 title.setGravity(Gravity.CENTER);                 break;             case 2:                 title.setGravity(Gravity.LEFT);                 break;         }         title.setTextColor(Color.rgb(random.nextInt(250), random.nextInt(250), random.nextInt(250)));         title.setTextSize(random.nextInt(55) + 10);     } } 

And this is my LogCat

02-20 10:53:19.293: I/Adreno200-EGLSUB(5816): <ConfigWindowMatch:2078>: Format RGBA_8888. 02-20 10:53:19.303: D/memalloc(5816): /dev/pmem: Mapped buffer base:0x5c914000 size:14135296 offset:10366976 fd:64 02-20 10:53:19.303: E/(5816): Can't open file for reading 02-20 10:53:19.303: E/(5816): Can't open file for reading 02-20 10:53:19.303: D/OpenGLRenderer(5816): Enabling debug mode 0 02-20 10:53:19.373: D/memalloc(5816): /dev/pmem: Mapped buffer base:0x5db58000 size:3768320 offset:0 fd:67 02-20 10:53:20.143: W/dalvikvm(5816): threadid=11: thread exiting with uncaught exception (group=0x40abc210) 02-20 10:53:20.143: E/AndroidRuntime(5816): FATAL EXCEPTION: Thread-3102 02-20 10:53:20.143: E/AndroidRuntime(5816): android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views. 02-20 10:53:20.143: E/AndroidRuntime(5816):     at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:4039) 02-20 10:53:20.143: E/AndroidRuntime(5816):     at android.view.ViewRootImpl.invalidateChild(ViewRootImpl.java:722) 02-20 10:53:20.143: E/AndroidRuntime(5816):     at android.view.ViewRootImpl.invalidateChildInParent(ViewRootImpl.java:771) 02-20 10:53:20.143: E/AndroidRuntime(5816):     at android.view.ViewGroup.invalidateChild(ViewGroup.java:4112) 02-20 10:53:20.143: E/AndroidRuntime(5816):     at android.view.View.invalidate(View.java:8639) 02-20 10:53:20.143: E/AndroidRuntime(5816):     at android.view.View.invalidate(View.java:8590) 02-20 10:53:20.143: E/AndroidRuntime(5816):     at android.widget.TextView.setGravity(TextView.java:2538) 02-20 10:53:20.143: E/AndroidRuntime(5816):     at com.example.saikoro.MainActivity.title(MainActivity.java:58) 02-20 10:53:20.143: E/AndroidRuntime(5816):     at com.example.saikoro.MainActivity$1.run(MainActivity.java:36) 

Answer 1

Change your startingUp() to this.

 private void startingUp() {     Thread timer = new Thread() { //new thread                  public void run() {             Boolean b = true;             try {                 do {                     counter++;                     title();                     sleep(1000);                      runOnUiThread(new Runnable() {                       @Override                     public void run() {                         // TODO Auto-generated method stub                          title.clearComposingText();                     }                 });                   }                 while (b == true);             } catch (IntruptedException e) {                 e.printStackTrace();             }             finally {             }         };     };     timer.start(); } 

You can't modify views from non-UI thread.