Entrypoint Of Android Application

When we develop an Android application, we always start from the onCreate() method of the main activity. It is obvious that there are some initializations that should be done befor

Solution 1:

The first "entry" point is the application class as Kingston pointed out.

However, the easiest thing to get the very first starting point is to check the stack when debugging onCreate.

You may check Instrumentation, this sound somewhat like what you want.

http://developer.android.com/reference/android/app/Instrumentation.html

MainActivity.onCreate(Bundle)line:12Instrumentation.callActivityOnCreate(Activity,Bundle)line:1047ActivityThread.performLaunchActivity(ActivityThread$ActivityRecord,Intent)line:2627ActivityThread.handleLaunchActivity(ActivityThread$ActivityRecord,Intent)line:2679ActivityThread.access$2300(ActivityThread,ActivityThread$ActivityRecord,Intent)line:125ActivityThread$H.handleMessage(Message)line:2033ActivityThread$H(Handler).dispatchMessage(Message)line:99Looper.loop()line:123ActivityThread.main(String[])line:4627Method.invokeNative(Object,Object[],Class,Class[],Class,int,boolean)line:notavailable [nativemethod]  
Method.invoke(Object,Object...)line:521ZygoteInit$MethodAndArgsCaller.run()line:868ZygoteInit.main(String[])line:626NativeStart.main(String[])line:notavailable [nativemethod]  

Solution 2:

You should extend the Application class and override the onCreate method.

For reference:Application class

Solution 3:

I don't know it myself, but it sounds an interesting question. This is the code that fires a new Activity and following the code, you'll end up in JNI code

publicvoidstartActivityForResult(Intent intent, int requestCode) {
        if (mParent == null) {
            Instrumentation.ActivityResultar=
                mInstrumentation.execStartActivity(
                    this, mMainThread.getApplicationThread(), mToken, this,
                    intent, requestCode);
            if (ar != null) {
                mMainThread.sendActivityResult(
                    mToken, mEmbeddedID, requestCode, ar.getResultCode(),
                    ar.getResultData());
            }
            if (requestCode >= 0) {
                // If this start is requesting a result, we can avoid making// the activity visible until the result is received.  Setting// this code during onCreate(Bundle savedInstanceState) or onResume() will keep the// activity hidden during this time, to avoid flickering.// This can only be done when a result is requested because// that guarantees we will get information back when the// activity is finished, no matter what happens to it.
                mStartedActivity = true;
            }
        } else {
            mParent.startActivityFromChild(this, intent, requestCode);
        }
    }

Android source code is available, but it's a bit tricky to get it because it's poorly documented. You'll have to install repo and then download the framework/base project