[disable/re-enable the expansion CoordinatorLayout behavior]#Android

DisableableAppBarLayoutBehavior.java

public class DisableableAppBarLayoutBehavior extends AppBarLayout.Behavior {
    private boolean mEnabled;

    public DisableableAppBarLayoutBehavior() {
        super();
    }

    public DisableableAppBarLayoutBehavior(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public void setEnabled(boolean enabled) {
        mEnabled = enabled;
    }

    @Override
    public boolean onStartNestedScroll(CoordinatorLayout parent, AppBarLayout child, View directTargetChild, View target, int nestedScrollAxes) {
        return mEnabled && super.onStartNestedScroll(parent, child, directTargetChild, target, nestedScrollAxes);
    }

    public boolean isEnabled() {
        return mEnabled;
    }
}

AppBarLayout myAppBar = ....;
CoordinatorLayout.LayoutParams layoutParams = (CoordinatorLayout.LayoutParams) myAppBar.getLayoutParams();
((DisableableAppBarLayoutBehavior) layoutParams.getBehavior()).setEnabled(false);