Question

I’m trying to create a new thread in the onCreate() of an activity, but instead of creating a new thread and executing the runnable’s code in it, the runnable code is executing in the main thread of my program. A new thread never seems to be created.

The onCreate() code:

@Override
protected void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    setContentView(R.layout.monster_layout);
    runningMonsterViewActivity = this;
    Thread.currentThread().setName("Main Thread");
    Log.v(TAG, "onCreate() has run");
    Thread genThread = new Thread(new TestRunnable());
    genThread.run();
}

The runnable code:

import android.os.Handler;
import android.util.Log;

public class TestRunnable implements Runnable{
String TAG = "TestRunnable";

    public TestRunnable()
    {
    //  mainThreadHandler = h;
    }
    @Override
    public void run() {
        for(int i=0; i < 1000; i++){
            Log.v(TAG, new Integer(i).toString());
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }

    }
}

The stack trace I got when I paused the code when it was executing:

DalvikVM[localhost:8621] (Suspended)    
    Thread [<1> Main Thread] (Suspended)    
        VMThread.sleep(long, int) line: not available [native method]   
        Thread.sleep(long, int) line: 1306  
        Thread.sleep(long) line: 1286   
        TestRunnable.run() line: 18 
        Thread.run() line: 1096 
        MonsterViewActivity.onCreate(Bundle) line: 49   
        Instrumentation.callActivityOnCreate(Activity, Bundle) line: 1047   
        ActivityThread.performLaunchActivity(ActivityThread$ActivityRecord, Intent) line: 2627  
        ActivityThread.handleLaunchActivity(ActivityThread$ActivityRecord, Intent) line: 2679   
        ActivityThread.access$2300(ActivityThread, ActivityThread$ActivityRecord, Intent) line: 125 
        ActivityThread$H.handleMessage(Message) line: 2033  
        ActivityThread$H(Handler).dispatchMessage(Message) line: 99 
        Looper.loop() line: 123 
        ActivityThread.main(String[]) line: 4627    
        Method.invokeNative(Object, Object[], Class, Class[], Class, int, boolean) line: not available [native method]  
        Method.invoke(Object, Object...) line: 521  
        ZygoteInit$MethodAndArgsCaller.run() line: 868  
        ZygoteInit.main(String[]) line: 626 
        NativeStart.main(String[]) line: not available [native method]  
    Thread [<6> Binder Thread #2] (Suspended)   
    Thread [<5> Binder Thread #1] (Suspended)   
    Daemon System Thread [<3> Signal Catcher] (Suspended)   
    Daemon System Thread [<2> HeapWorker] (Suspended)   

Answer 1

You just need to change genThread.run(); to genThread.start();

Right now, your code calls the run() method from the main thread. start() will actually start a new thread and will execute the run() method on that thread, which is the desired behaviour.