Question

The books I have are abysmal at explaining how to work with the lifecycle, there’s a lot I’m missing that I’m hoping somebody can fill in.

My app structure is that when it’s first started, it starts an activity full of legalbabble that the user has to accept. When he says ‘ok’, I start my main activity and then I call finish like this:

public void onClick(View view) { //as a result of "I accept"
    Intent mainIntent = new Intent(mParent, EtMain.class);
    startActivity(mainIntent); // Start the main program
    finish();
}

Then in EtMain in the onCreate method, I’ve got some tabs and I instantiate some classes:

super.onCreate(savedInstanceState);
setContentView(R.layout.main);

mTabHost = (TabHost)findViewById(android.R.id.tabhost);
SetupTabs.setMyTabs(mTabHost, this);

mComData = new ComFields(this); // Create the objects
mDepWx = new WxFields(this, DepArr.Departure);
mArrWx = new WxFields(this, DepArr.Arrival);
mDepVs = new DepFields(this);
mArrVs = new ArrFields(this);
mTabHost.setOnTabChangedListener(new OnTabChangeListener(){
}

Questions:
The ‘finish’ in the first fragment should terminate the legalbabble activity so it’ll never be restarted, right? And the EtMain one will remain forever (until killed externally), even if my app gets pushed to the background, right?

The way it is now, when EtMain gets pushed and later brought to the foreground (by tapping on the icon), it goes through the legalbabble screen as though it’s a complete start – that’s what I’d like to prevent – going thru the legalbabble screen again.

It would seem that I’d want to override onRestart in the second code fragment and put something in there to restart the app, right? That’s the part I’m unclear about.

My question then is what needs to be done in onRestart. Do I have to recreate all the tabs and data in the tabs and all my object instantiations? Or is the memory state of the app saved someplace and then is restored back to the state that it was in before something else was brought to the foreground in which case not much needs to be done because all the objects and listeners will still be there?

Answer 1

I think the problem is that the launch activity in your manifest is the legalbabble activity, so when you click on the icon, the system launches another one. A better architecture would be to launch the legalbabble activity it from your EtMain activity in the onCreate method of the latter, using startActivityForResult. From the docs:

As a special case, if you call startActivityForResult() with a requestCode >= 0 during the initial onCreate(Bundle savedInstanceState)/onResume() of your activity, then your window will not be displayed until a result is returned back from the started activity.

When you get the result in onActivityResult, you can call finish() if the legal stuff was declined; otherwise everything will proceed normally.

This avoids the problem that the launch activity defined in your manifest finishes when the legal stuff is accepted.