android - "This type is final so it cannot be inherited from"-ViewPager2

我正在尝试扩展 ViewPager2 类，以便可以左右拖动我的SeekBarPreference。

class ViewPager2Custom(context: Context) : ViewPager2(context) {

}

但是我在ViewPager2(context)上得到了“此类型是最终类型，因此不能从它继承”红线。

任何想法？

最佳答案

NestedScrollableHost类完全可以满足您的需求:https://github.com/android/views-widgets-samples/blob/master/ViewPager2/app/src/main/java/androidx/viewpager2/integration/testapp/NestedScrollableHost.kt
基本想法是，您重写onInterceptTouchEvent并通过ViewPager2方法请求NestedScrollableHost的父级(在本例中为requestDisallowInterceptTouchEvent)不允许其拦截触摸事件。

// Pseudo-code for NestedScrollableHost

@Override
public boolean onInterceptTouchEvent(MotionEvent event) {
    handleInterceptTouchEvent(event);
    return super.onInterceptTouchEvent(event);
}

private void handleInterceptTouchEvent(MotionEvent event) {
    // Early return if parent viewpager is null or child can't scroll in same direction as parent
    if (getParentViewPager() == null ||
            (!canChildScrollVertically(-1f) && !canChildScrollVertically(1f))) {
        return;
    }

    switch (event.getAction()) {
        // You can tailor your class to handle the event in the way you want to,
        // e.g. do something on down and move events:
        case MotionEvent.ACTION_DOWN:
            // Disallow the parent (and all subsequent parents) to intercept touch events.
            getParent().requestDisallowInterceptTouchEvent(disallow);
        case MotionEvent.ACTION_MOVE:
            // Some other logic.
    }
}

您可以将NestedScrollableHost放在XML中的ViewPager2和(在您的情况下)SeekBarPreference之间。