Programmatically show Toolbar after hidden by scrolling (Android Design Library)

Question

I have the following layout: a drawer, with the main content view having a AppBarLayout, RecyclerView and a TextView. When I scroll the recycler, the toolbar is correctly hi

Answer 1

You need to put header to the RecyclerView to the height of the AppBarLayout. I.e at position 0 of the RecyclerView you need to add the header and then the rest of the elements.

If you want to forcefully show the Toolbar, actually the AppBarLayout with offsetting top and bottom of the AppBarLayout dependent views (it is called Behavoir) . You need to keep reference of height of the AppBarLayout, as we know that height is the distance between top and bottom of view Rect.

Assuming that your AppBarLayout hold only a Toolbar:

int mAppBarLayoutHeight = mAppBarLayout.getBottom() - mAppBarLayout.getTop(); //initial, normal height

 private void showToolbar(){
        if(this.mAnimator == null) {
            this.mAnimator = new ValueAnimator();
            this.mAnimator.setInterpolator(new DecelerateInterpolator());
            this.mAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                @Override
                public void onAnimationUpdate(ValueAnimator animation) {
                 int animatedOffset = (int) animation.getAnimatedValue();
                 mToolbar.offsetTopBottom(animatedOffset/2);
                }
            });
        } else {
            this.mAnimator.cancel();
        }

        this.mAnimator.setIntValues(0, mAppBarLayoutHeight);
        this.mAnimator.start();
    }