如何更改FragmentStatePagerAdapter的getItem中的片段

public class CustomPagerAdapter extends FragmentStatePagerAdapter {
    private static final int FRAGMENT_ONE = 0;
    private static final int FRAGMENT_TWO = 1;
    private static final int FRAGMENT_THREE = 2;

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

    @Override
    public Fragment getItem(int position) {
        switch (position) {
            case FRAGMENT_ONE:
                return new FragmentOne();
            case FRAGMENT_TWO:
                return new FragmentTwo();
            case FRAGMENT_THREE:
                return new FragmentThree();
            default:
                return null;
        }
    }

    @Override
    public int getCount() {
        return 3; // 返回片段的数量
    }
}