android - 如何在按下按钮时使 ScrollView 滚动？

Question

我的问题实际上很简单，我找不到解决我问题中提到的问题的方法。我尝试了 AsyncTask，它根本不起作用，还尝试了按钮的 OnFocusChange 事件……我现在有点绝望。

希望大家帮帮忙! :)

异步任务版本:

private void creationVoid(){
    (...)
    btScrollDown.setOnTouchListener(new View.OnTouchListener() {
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            if(event.getAction() == MotionEvent.ACTION_DOWN)
                downPressed = true;
            if(event.getAction() == MotionEvent.ACTION_UP)
                downPressed = false;
            new ScrollDownTask().execute();
            return true;
        }
    });
(...)
}


private void scrollDown(){
    btScrollUp.setVisibility(View.VISIBLE);
    scrollView.scrollTo(scrollView.getScrollX(), scrollView.getScrollY() + 15);
    if(scrollView.getScrollY() == scrollView.getChildAt(scrollView.getChildCount()-1).getBottom() - 763) {
        btScrollDown.setVisibility(View.GONE);
    }
}

private class ScrollDownTask extends AsyncTask<String, Void, String>{
    @Override
    protected String doInBackground(String... params) {return null;}

    @Override
    protected void onPostExecute(String s) {
        while(downPressed)
            scrollDown();
    }
}

OnFocusChange 版本:

private void creationVoid(){
    (...)
    btScrollDown.setOnFocusChangeListener(new View.OnFocusChangeListener() {
        @Override
        public void onFocusChange(View v, boolean hasFocus) {
            while(hasFocus)
                scrollDown();
        }
    });
    (...)
}

Answer 1

按下按钮时，可以调用smoothScrollBy 或smoothScrollTo 方法。但是，您必须根据您的要求计算 ScrollView 的量。希望这可以帮助。

https://developer.android.com/reference/android/widget/ScrollView.html#smoothScrollBy(int,%20int)