android - 如何通过 Viewpager 的 setCurrentItem 方法使我的箭头不可见？

Question

在我的 MainActivity 的 Oncreate 中，我添加了这段代码:

mDateAreaSlider.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageSelected(int arg0) {

                    // Hide right arrow if reach last position 
                    if (arg0 == adapter.DateList.length - 1) {
                        mButtonNext.setVisibility(View.INVISIBLE);
                        mButtonBack.setVisibility(View.VISIBLE);
                    }

                    // Hide left arrow if reach first position 
                    else if (arg0 == 0) {
                        mButtonBack.setVisibility(View.INVISIBLE);
                        mButtonNext.setVisibility(View.VISIBLE);
                    }

                    // Else show both arrows
                    else {
                        mButtonBack.setVisibility(View.VISIBLE);
                        mButtonNext.setVisibility(View.VISIBLE);
                    }
                }
            }

            @Override
            public void onPageScrolled(int arg0, float arg1, int arg2) {
                // TODO Auto-generated method stub
                ifSingding = true;
            }

            @Override
            public void onPageScrollStateChanged(int arg0) {
                // TODO Auto-generated method stub
            }
        });

然后在按钮上单击我添加此代码:

mDateAreaSlider.setCurrentItem(0);

但问题是它可以滑动到我选择的页面，但不会让我的箭头不可见。

注意:这两个箭头是主布局中的ImageView，不是膨胀布局。所以它与适配器无关。

Answer 1

将您的原始代码替换为:

final ViewPager.OnPageChangeListener onPageChangeListener = new ViewPager.OnPageChangeListener() {
        @Override
        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

        }

        @Override
        public void onPageSelected(int position) {
            if (position == adapter.DateList.length - 1) {
                    mButtonNext.setVisibility(View.INVISIBLE);
                    mButtonBack.setVisibility(View.VISIBLE);
                }

                // Hide left arrow if reach first position 
                else if (position == 0) {
                    mButtonBack.setVisibility(View.INVISIBLE);
                    mButtonNext.setVisibility(View.VISIBLE);
                }

                // Else show both arrows
                else {
                    mButtonBack.setVisibility(View.VISIBLE);
                    mButtonNext.setVisibility(View.VISIBLE);
                }
        }

        @Override
        public void onPageScrollStateChanged(int state) {

        }
};
mDateAreaSlider.addOnPageChangeListener(onPageChangeListener);

在您的按钮点击时执行此代码

mDateAreaSlider.setCurrentItem(0);
mDateAreaSlider.post(new Runnable() {
        @Override
        public void run() {
            onPageChangeListener.onPageSelected(0);
        }
});