Need to disable expand on CollapsingToolbarLayout for certain fragments

Question

I have a AppCompatActivity that controls replacing many fragments. Here is my layout for it.

activity_main.xml

Answer 1

You can lock appbarlayout expansion by resetting collapsing toolbar height to toolbar height

toolbarHeight = toolbar.getLayoutParams().height;

if (expand) {
    collapsingToolbar.getLayoutParams().height = getResources().getDimensionPixelOffset(R.dimen.collapsingToolbarDefaultHeight);
    appBarLayout.setExpanded(true, true);
} else {
    //collapse
    //** it is important you do this before resetting **
    appBarLayout.setExpanded(false, true);
    appBarLayout.postDelayed(new Runnable() {
        @Override
        public void run() {
            collapsingToolbar.getLayoutParams().height = toolbarHeight;
        }
     }, 700/* 600 is default animation time to collapse */);
}