Question

与ScrollView .scrollTo not working? Saving ScrollView position on rotation

相同的问题

我在onCreate中向scrollView动态添加项目。添加完所有项目后，我尝试以下操作：

    // no effect
    ScrollView mainScroll = (ScrollView) findViewById(R.id.average_scroll_mainScroll);

    // no effect
    ScrollView mainScroll = (ScrollView) findViewById(R.id.average_scroll_mainScroll);
    mainScroll.post(new Runnable() {
        public void run(){
            ScrollView mainScroll = (ScrollView) findViewById(R.id.average_scroll_mainScroll);
            mainScroll.scrollTo(0, 0);
        } 
    });

    // works like a charm
    ScrollView mainScroll = (ScrollView) findViewById(R.id.average_scroll_mainScroll);
    mainScroll.postDelayed(new Runnable() {
        public void run(){
            ScrollView mainScroll = (ScrollView) findViewById(R.id.average_scroll_mainScroll);
            mainScroll.scrollTo(0, 0);
        } 
    }, 30);

我的结论是有一些像'DOM-ready'这样的事件？有没有回调？

Answer 1

您不需要扩展ScrollView并根据David Daudelin为this question提供的答案创建自己的。

获取ViewTreeObserver的{{1}}并向ScrollView添加OnGlobalLayoutListener。然后从ViewTreeObserver的{{1}}方法调用ScrollView.scrollTo(x,y)方法。代码：

onGlobalLayout()

Answer 2

这对我有用，将scrollView.scrollTo()替换为

     scrollView.post(new Runnable() {
        @Override
        public void run() {
            scrollView.scrollTo(0, ScrollViewYPosition);//0 is x position
        }
    });

Vasily Kabunov在

中的回答得到了帮助

ScrollView .scrollTo not working? Saving ScrollView position on rotation

Answer 3

当您对ScrollView进行一些更改时，它需要一段时间才能将布局更改复制到显示列表，并通知ScrollView它确实允许滚动到某个位置。

我已经设法通过使用我自己的ScrollView扩展ScrollView并添加一个根据需要添加OnGlobalLayoutListener（由MH建议）并稍后滚动的方法。它比将它应用于您需要它的每个案例都要自动化一些（但是您需要使用新的ScrollView）。无论如何，这是相关的代码：

public class ZScrollView extends ScrollView {

    // Properties
    private int desiredScrollX = -1;
    private int desiredScrollY = -1;
    private OnGlobalLayoutListener gol;

    // ================================================================================================================
    // CONSTRUCTOR ----------------------------------------------------------------------------------------------------

    public ZScrollView(Context __context) {
        super(__context);
    }

    public ZScrollView(Context __context, AttributeSet __attrs) {
        super(__context, __attrs);
    }

    public ZScrollView(Context __context, AttributeSet __attrs, int __defStyle) {
        super(__context, __attrs, __defStyle);
    }

    // ================================================================================================================
    // PUBLIC INTERFACE -----------------------------------------------------------------------------------------------

    public void scrollToWithGuarantees(int __x, int __y) {
        // REALLY Scrolls to a position
        // When adding items to a scrollView, you can't immediately scroll to it - it takes a while
        // for the new addition to cycle back and update the scrollView's max scroll... so we have
        // to wait and re-set as necessary

        scrollTo(__x, __y);

        desiredScrollX = -1;
        desiredScrollY = -1;

        if (getScrollX() != __x || getScrollY() != __y) {
            // Didn't scroll properly: will create an event to try scrolling again later

            if (getScrollX() != __x) desiredScrollX = __x;
            if (getScrollY() != __y) desiredScrollY = __y;

            if (gol == null) {
                gol = new OnGlobalLayoutListener() {
                    @Override
                    public void onGlobalLayout() {
                        int nx = desiredScrollX == -1 ? getScrollX() : desiredScrollX;
                        int ny = desiredScrollY == -1 ? getScrollY() : desiredScrollY;
                        desiredScrollX = -1;
                        desiredScrollY = -1;
                        scrollTo(nx, ny);
                    }
                };

                getViewTreeObserver().addOnGlobalLayoutListener(gol);
            }
        }
    }
}

对我来说非常有用，因为我想在添加它之后立即滚动到ScrollView中的给定视图。

Answer 4

尝试使用此功能：（kotlin）

             myScrollView.post(Runnable {
                 myScrollView.scrollTo(0, scrollValue)
             })

ScrollView scrollTo不起作用

4 个答案: