android - 是否可以知道ViewPager中显示的是哪张图片？

Question

我有两张图片。我使用 ViewPager 来单独显示它们。我想知道屏幕上显示的是哪些。你能帮我解决吗？例如，当我滚动屏幕时，第一张图片将显示并 toast 一条消息，例如“这是第一张图片”，对第二张图片做同样的事情。提前致谢。这是我的代码

public class ViewPagerExample extends FragmentActivity{

    private MyAdapter mAdapter;
    private ViewPager mPager;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    mAdapter = new MyAdapter(getSupportFragmentManager());

    mPager = (ViewPager) findViewById(R.id.pager);
    mPager.setAdapter(mAdapter);
    }

    public static class MyAdapter extends FragmentPagerAdapter {
    public MyAdapter(FragmentManager fm) {
    super(fm);
    }

    @Override
    public int getCount() {
    return 2;
    }

    @Override
    public Fragment getItem(int position) {
    switch (position) {
    case 0:
    {
    return new ImageFragment(R.drawable.image1);
    }
    case 1:
    {
    return new ImageFragment(R.drawable.image2);
    }

    default:
    return null;
    }
    }
    }
    }

和 ImageFragment 类

public class ImageFragment extends Fragment {
    private final int imageResourceId;

    public ImageFragment(int imageResourceId) {
    this.imageResourceId = imageResourceId;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Log.e("Test", "hello");
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);

    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
    Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.image_layout, container, false);
    ImageView imageView = (ImageView) view.findViewById(R.id.imageView1);
    imageView.setImageResource(imageResourceId);
    return view;
    }
    }

Answer 1

尝试这样的事情

mPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }

            @Override
            public void onPageSelected(int pager_position) {

                // show toast here for images
            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });