How to implement Custom Collapsable Toolbar in android?

The AppBarComponentprovides a method called .setExpanded(boolean expanded), which allows you to expand your AppBarComponent.

But keep in mind, that this method relies on this layout being a direct child of a CoordinatorLayout.

You can read this for more information.

If you want to animate to a custom offset, try using the setTopAndBottomOffset(int) method.

CoordinatorLayout.LayoutParams params = (CoordinatorLayout.LayoutParams) appBar.getLayoutParams();
final AppBarLayout.Behavior behavior = (AppBarLayout.Behavior) params.getBehavior();
if (behavior != null) {
    ValueAnimator valueAnimator = ValueAnimator.ofInt();
    valueAnimator.setInterpolator(new DecelerateInterpolator());
    valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
        @Override
        public void onAnimationUpdate(ValueAnimator animation) {
            behavior.setTopAndBottomOffset((Integer) animation.getAnimatedValue());
            appBar.requestLayout();
        }
    });
    valueAnimator.setIntValues(0, -900);
    valueAnimator.setDuration(400);
    valueAnimator.start();
}