android – FragmentPagerAdapter – 当用户转到新标签时,如何检测到滑动或标签点击？

我有@L_180_1@mainActivity,在FragmentPagerAdapter中有三个片段,如下所示.如何查看用户从第一个片段到第二个片段,或从第二个到第三个,通过滑动或点击标签？我看到getItem()方法总是没有被调用,因为我已经声明了mViewPager.setOffscreenPageLimit(2);

public class MainThreeTabAdapter extends FragmentPagerAdapter {

    private final String[] CONTENT = new String[]{"News","ReWARDs","Me"};

    public MainThreeTabAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        if (position == 0) {
            return NewsFragment.newInstance();
        } else if (position == 1) {
            return ReWARDsFragment.newInstance();
        } else if (position == 2) {
            return MeFragment.newInstance(true,App.getAccountData().getId());
        } else {
            return null;
        }

    }

    @Override
    public CharSequence getPagetitle(int position) {
        return CONTENT[position % CONTENT.length];
    }

    @Override
    public int getCount() {
        return CONTENT.length;
    }
}

在MainActivity的onCreate()

@H_956_2@mainThreeTabAdapter = new MainThreeTabAdapter(getFragmentManager()); // Set up the ViewPager with the sections adapter. // this ensures that 2 tabs on each side of current are kept in memory,which is all we need for our case. Default = 1 // this is all taken from the Quickreturn facebook sample app mViewPager.setOffscreenPageLimit(2); mViewPager.setAdapter(mainThreeTabAdapter);