Programmatically collapse or expand CollapsingToolbarLayout

Question

Simple question, but I can't find an answer. How can I collapse or expand the CollapsingToolbarLayout programmatically?

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Answer 1

Using Support Library v23, you can call appBarLayout.setExpanded(true/false).

Further reading: AppBarLayout.setExpanded(boolean)

Answer 2

I use this code for collapsing toolbar. Still cannot find a way to expand it.

public void collapseToolbar(){
    CoordinatorLayout.LayoutParams params = (CoordinatorLayout.LayoutParams) appbarLayout.getLayoutParams();
    behavior = (AppBarLayout.Behavior) params.getBehavior();
    if(behavior!=null) {
        behavior.onNestedFling(rootLayout, appbarLayout, null, 0, 10000, true);
    }
}

Edit 1: The same function with negative velocityY but the toolbar is not expanded 100% and false for last param should work

public void expandToolbar(){
    CoordinatorLayout.LayoutParams params = (CoordinatorLayout.LayoutParams) appbarLayout.getLayoutParams();
    behavior = (AppBarLayout.Behavior) params.getBehavior();
    if(behavior!=null) {
        behavior.onNestedFling(rootLayout, appbarLayout, null, 0, -10000, false);
    }
}

Edit 2: This code do the trick for me

public void expandToolbar(){
    CoordinatorLayout.LayoutParams params = (CoordinatorLayout.LayoutParams) appbarLayout.getLayoutParams();
    behavior = (AppBarLayout.Behavior) params.getBehavior();
    if(behavior!=null) {
        behavior.setTopAndBottomOffset(0);
        behavior.onNestedPreScroll(rootLayout, appbarLayout, null, 0, 1, new int[2]);
    }
}

• setTopAndBottomOffset do expand the toolbar
• onNestedPreScroll do show the content inside expanded toolbar

Will try to implement Behavior by myself.