java - What is causing this runnable thread to be skipped -

i have attempted follow examples have found on implementing runnable thread, reason code skipped.

for sake of having better understanding, can tell me preventing thread code executing?

mainactivity.java:

import android.os.bundle; import android.support.v4.app.fragment; import android.support.v7.app.actionbaractivity; import android.view.layoutinflater; import android.view.menu; import android.view.menuitem; import android.view.view; import android.view.viewgroup; import android.widget.textview;  public class mainactivity extends actionbaractivity {      @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_main);          if (savedinstancestate == null) {             getsupportfragmentmanager().begintransaction()                     .add(r.id.container, new placeholderfragment()).commit();         }     }      @override     public boolean oncreateoptionsmenu(menu menu) {          string textinfo = "";          getmenuinflater().inflate(r.menu.main, menu);         textview tv = (textview) findviewbyid(r.id.infotext);         textinfo += "testing android runnable thread.\n";         tv.settext(textinfo);          runnable runnable = new runnable() {             public void run() {                  global.classtext += "running in thread!\n";                  long endtime = system.currenttimemillis() + 20 * 1000;                  while (system.currenttimemillis() < endtime) {                     synchronized (this) {                         try {                             wait(endtime - system.currenttimemillis());                         } catch (exception e) {                         }                     }                  }             }         };          thread mythread = new thread(runnable);         mythread.start();          textinfo += global.classtext;         textinfo += "finished.\n";         tv.settext(textinfo);          return true;     }      @override     public boolean onoptionsitemselected(menuitem item) {         // handle action bar item clicks here. action bar         // automatically handle clicks on home/up button, long         // specify parent activity in androidmanifest.xml.         int id = item.getitemid();         if (id == r.id.action_settings) {             return true;         }         return super.onoptionsitemselected(item);     }      /**      * placeholder fragment containing simple view.      */     public static class placeholderfragment extends fragment {          public placeholderfragment() {         }          @override         public view oncreateview(layoutinflater inflater, viewgroup container,                 bundle savedinstancestate) {             view rootview = inflater.inflate(r.layout.fragment_main, container,                     false);             return rootview;         }     } } 

fragment_main.xml:

<linearlayout xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:tools="http://schemas.android.com/tools"     android:layout_width="fill_parent"     android:layout_height="fill_parent"     android:orientation="vertical"      >      <textview         android:id="@+id/infotext"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:text="@string/infotext" /> </linearlayout> 

strings.xml:

<?xml version="1.0" encoding="utf-8"?> <resources>      <string name="app_name">andorid thread test</string>     <string name="action_settings">settings</string>     <string name="infotext">android thread test</string> </resources> 

androidmanifest.xml:

<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android"     package="com.apollo.androidthreadtest"     android:versioncode="1"     android:versionname="1.0" >      <uses-sdk         android:minsdkversion="8"         android:targetsdkversion="19" />      <application         android:allowbackup="true"         android:icon="@drawable/ic_launcher"         android:label="@string/app_name"         android:theme="@style/apptheme" >         <activity             android:name="com.apollo.androidmysqltest.mainactivity"             android:label="@string/app_name" >             <intent-filter>                 <action android:name="android.intent.action.main" />                  <category android:name="android.intent.category.launcher" />             </intent-filter>         </activity>     </application>  </manifest> 

the code doesn't produce errors. runs on android output:

testing androd runnable thread. finished.

the lines in thread ("running in thread!") never displays , debug shows whole block skipped.

since running different thread, cannot expect code execute sequentially like:

        thread mythread = new thread(runnable);         mythread.start();          textinfo += global.classtext;         textinfo += "finished.\n";         tv.settext(textinfo);          return true; 

by time main thread hits return true, global.classtext may have not been changed parallel thread yet

to see mean, try changing code this:

            thread mythread = new thread(runnable);             mythread.start();              while(mythread.isalive()){                 //wait till thread finishes             }              textinfo += global.classtext;             textinfo += "finished.\n";             tv.settext(textinfo);              return true;