使用ViewPager时getActivity可以返回null吗？

Question

  public class SectionsPagerAdapter extends FragmentStatePagerAdapter {

    private int numOfTabs;

    SectionsPagerAdapter(FragmentManager fm, int numOfTabs) {
        super(fm);
        this.numOfTabs = numOfTabs;
    }

    @Override
    public Fragment getItem(int position) {
        switch (position){
            case 0:
                Log.i(TAG, "Fragment Pos: "+ position);
                return new Tab1();
            case 1:
                Log.i(TAG, "Fragment Pos: "+ position);
                return new Tab2();
            case 2:
                Log.i(TAG, "Fragment Pos: "+ position);
                return new Tab3();
            case 3:
                Log.i(TAG, "Fragment Pos: "+ position);
                return new Tab4();
            case 4:
                Log.i(TAG, "Fragment Pos: "+ position);
                return new Tab5();
            case 5:
                Log.i(TAG, "Fragment Pos: "+ position);
                return new Tab6();
                default:
                    return null;
        }
    }

    @Override
    public int getCount() {
        // Get total pages
        return numOfTabs;
    }
}

setupViewPager（）方法：

mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager(), tabLayout.getTabCount());

    // Set up the ViewPager with the sections adapter
    mViewPager = findViewById(R.id.viewPager);

    mViewPager.setAdapter(mSectionsPagerAdapter);

    mViewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));

Answer 1

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u始终可以使用视图本身的上下文viewpager.getcontext()

使用getactivity()是可以的，只要您确定在这一点上活动不是空的，例如在onactivitycreated中。

如果您想摆脱lint警告，只需对getactivityvar进行null检查即可。