We'll design this type of sample Android App using Collapsing Toolbar Layout:

First of all add these dependencies to your gradle file:

dependencies {
    ...
    compile 'com.android.support:design:26.0.0-alpha1'
    ...
   }

Here I used version 26.0.0-alpha1 and it's the latest version (till 26th July, 2017), you should use the latest version.

Your XML file should contain a CoordinatorLayout to you CollapsingToolbarLayout.

Inside CoordinatorLayout take two widgets AppBarLayout and NestedScrollView as siblings. AppBarLayout contains a widget CollapsingToolbarLayout. Inside it I took an ImageView and my custom Toolbar.

NestedScrollView holds our rest of the contents. I used only a TextView to show an article.

AppBarStateChangeListener is an abstract class. It helps to listen the state change of AppBarLayout.

Inside the onCreate() method of MainActivity we can listen the state change by this method and take action:

appBarLayout.addOnOffsetChangedListener(new AppBarStateChangeListener() {
    @Override
    public void onStateChanged(AppBarLayout appBarLayout, State state) {
        if(state.equals(State.COLLAPSED)) {
            toolbar.setBackgroundResource(R.drawable.custom_toolbar);
            Toast.makeText(getApplicationContext(), "COLLAPSED", Toast.LENGTH_SHORT).show();
        }
        else if (state.equals(State.EXPANDED)) {
            toolbar.setBackgroundResource(R.color.transparent);
            Toast.makeText(getApplicationContext(), "EXPANDED", Toast.LENGTH_SHORT).show();
        }
        else if ((state.equals(State.IDLE))){
            Toast.makeText(getApplicationContext(), "IDLE", Toast.LENGTH_SHORT).show();
        }
    }
});

To get the whole project please clone it and run at your machine. If you see any error please let me know or send pull request.

Thank you. :-)