当到达底部时，移除底部的ScrollView渐变淡出

<ScrollView
    android:id="@+id/scrollView"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    
    <!-- 添加需要滚动的内容 -->
    
</ScrollView>

ScrollView scrollView = findViewById(R.id.scrollView);
scrollView.getViewTreeObserver().addOnScrollChangedListener(new ViewTreeObserver.OnScrollChangedListener() {
    @Override
    public void onScrollChanged() {
        if (scrollView.getChildAt(0).getBottom() <= (scrollView.getHeight() + scrollView.getScrollY())) {
            // 到达底部，执行渐变淡出效果
            ObjectAnimator fadeOut = ObjectAnimator.ofFloat(scrollView, "alpha", 1f, 0f);
            fadeOut.setDuration(500);
            fadeOut.start();
        }
    }
});