java - 在android中创建静态类实例

Question

我在这里看到了一个代码。也如下图所示：

我对静态类在Fragment fragment = new DemoObjectFragment();哪里有点困惑。public static class DemoObjectFragment extends Fragment那么我们如何调用fragment.setArguments(args);

public class CollectionDemoActivity extends FragmentActivity {
    // When requested, this adapter returns a DemoObjectFragment,
    // representing an object in the collection.
    DemoCollectionPagerAdapter mDemoCollectionPagerAdapter;
    ViewPager mViewPager;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_collection_demo);

        // ViewPager and its adapters use support library
        // fragments, so use getSupportFragmentManager.
        mDemoCollectionPagerAdapter =
                new DemoCollectionPagerAdapter(
                        getSupportFragmentManager());
        mViewPager = (ViewPager) findViewById(R.id.pager);
        mViewPager.setAdapter(mDemoCollectionPagerAdapter);
    }
}

// Since this is an object collection, use a FragmentStatePagerAdapter,
// and NOT a FragmentPagerAdapter.
public class DemoCollectionPagerAdapter extends FragmentStatePagerAdapter {
    public DemoCollectionPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int i) {
        Fragment fragment = new DemoObjectFragment();
        Bundle args = new Bundle();
        // Our object is just an integer :-P
        args.putInt(DemoObjectFragment.ARG_OBJECT, i + 1);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public int getCount() {
        return 100;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return "OBJECT " + (position + 1);
    }
}

// Instances of this class are fragments representing a single
// object in our collection.
public static class DemoObjectFragment extends Fragment {
    public static final String ARG_OBJECT = "object";

    @Override
    public View onCreateView(LayoutInflater inflater,
            ViewGroup container, Bundle savedInstanceState) {
        // The last two arguments ensure LayoutParams are inflated
        // properly.
        View rootView = inflater.inflate(
                R.layout.fragment_collection_object, container, false);
        Bundle args = getArguments();
        ((TextView) rootView.findViewById(android.R.id.text1)).setText(
                Integer.toString(args.getInt(ARG_OBJECT)));
        return rootView;
    }
}