Cannot resolve method 'addOnPageChangeListener(com.lhh.apst.library.AdvancedPagerSlidingTabStrip.PageListener)'

[pjxianga]

`public void setViewPager(ViewPager pager) { this.pager = pager;

    if (pager.getAdapter() == null) {
        throw new IllegalStateException("ViewPager does not have adapter instance.");
    }

    pager.addOnPageChangeListener(pageListener); // 这句代码有错误 错误信息:Cannot resolve method 'addOnPageChangeListener(com.lhh.apst.library.AdvancedPagerSlidingTabStrip.PageListener)'

    notifyDataSetChanged();
}`

[pjxianga]

21的ViewPager没有addOnPageChangeListener这个方法....