Question

我正在关注视图页面，但我不知道如何调用该类。

这是片段

public class FirstFragment extends Fragment {
    // Store instance variables
    private String title;
    private int page;

    // newInstance constructor for creating fragment with arguments
    public static FirstFragment newInstance(int page, String title) {
        FirstFragment fragmentFirst = new FirstFragment();
        Bundle args = new Bundle();
        args.putInt("someInt", page);
        args.putString("someTitle", title);
        fragmentFirst.setArguments(args);
        return fragmentFirst;
    }

    // Store instance variables based on arguments passed
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        page = getArguments().getInt("someInt", 0);
        title = getArguments().getString("someTitle");
    }

    // Inflate the view for the fragment based on layout XML
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
            Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_first, container, false);
        TextView tvLabel = (TextView) view.findViewById(R.id.tvLabel);
        tvLabel.setText(page + " -- " + title);
        return view;
    }
}

这里我试着打电话给班级

public class MainActivity extends AppCompatActivity {
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.register);
    toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);

MyPagerAdapter.getItem(1);
}

    public static class MyPagerAdapter extends FragmentPagerAdapter {
    private static int NUM_ITEMS = 3;

        public MyPagerAdapter(FragmentManager fragmentManager) {
            super(fragmentManager);
        }

        // Returns total number of pages
        @Override
        public int getCount() {
            return NUM_ITEMS;
        }

        // Returns the fragment to display for that page
        @Override
        public Fragment getItem(int position) {
            switch (position) {
            case 0: // Fragment # 0 - This will show FirstFragment
                return FirstFragment.newInstance(0, "Page # 1");
            case 1: // Fragment # 0 - This will show FirstFragment different title
                return FirstFragment.newInstance(1, "Page # 2");
            case 2: // Fragment # 1 - This will show SecondFragment
                return SecondFragment.newInstance(2, "Page # 3");
            default:
                return null;
            }
        }

        // Returns the page title for the top indicator
        @Override
        public CharSequence getPageTitle(int position) {
            return "Page " + position;
        }

    }

}

Answer 1

当应用于类时，static表示内部类不保留对外部环境的引用。它的行为与static方法不同。如果要调用静态类的方法，则仍需要该类的有效对象引用。 E.g。

  MyPagerAdapter adapter = new MyPagerAdapter(getSupportFragmentManager());
  adapter.getItem(1);

在这种特殊情况下，我强烈反对您使用此方法。 ViewPager调用getItem来实例化Fragment。在Adapter的引用上显式调用它不会返回该Fragment

的相同实例

为view pager调用静态类

1 个答案: