Question

我有以下代码尝试使用ViewPager。

问题是图像没有显示，我猜问题是片段没有被访问（或“被叫”）你能找出原因吗？

我在Fragment方法中添加了一个打印件来检查它是否已被访问。

这个ViewPager适配器，getItem应该返回片段的值，还是有问题？

 public class DemoCollectionPagerAdapter extends FragmentStatePagerAdapter {
     public static final String ARG_OBJECT = "Person_List";
     private ArrayList<Listitem> personArrayList;

     public DemoCollectionPagerAdapter(FragmentManager fm, ArrayList<Listitem> personArrayList)
     {
         super(fm);
         Log.d("s", "adapterview");
         this.personArrayList = personArrayList;
     }

     @Override
     public Fragment getItem(int i) {
         return DemoObjectFragment.newInstance(this.personArrayList.get(i));
     }

     @Override
     public int getCount() {
         return 1;
     }

这是代码的其余部分

public class SingleViewActivity extends FragmentActivity {
    ImageView imageView;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_page_view);

        ArrayList<Listitem> personArrayList = new ArrayList<Listitem>();

        ViewPager mViewPager = (ViewPager) findViewById(R.id.pager);
        Log.d("s", "singleview");
        Listitem item = new Listitem("1", "http://developer.android.com/assets/images/android_logo.png");
        personArrayList.add(item);

        DemoCollectionPagerAdapter mDemoCollectionPagerAdapter = new DemoCollectionPagerAdapter(getSupportFragmentManager(), personArrayList);
        mViewPager.setAdapter(mDemoCollectionPagerAdapter);
    }
}

public static class DemoObjectFragment extends Fragment {
    public static final String ARG_PERSON_LIST = "Person_List";
    private Listitem person;

    public static DemoObjectFragment newInstance(Listitem  items) {
        DemoObjectFragment f = new DemoObjectFragment();
        Bundle args = new Bundle();
        args.putParcelable(ARG_PERSON_LIST, items);
        f.setArguments(args);
        System.out.print("instance1");
        return f;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Bundle args = getArguments();

        if (args.containsKey(ARG_PERSON_LIST)) {
            this.person = args.getParcelable(ARG_PERSON_LIST);
        } else {
            this.person = null;
        }

    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        View rootView = inflater.inflate(
                        R.layout.fragment_collection_object, container, false);
        ImageView imageView = (ImageView) rootView.findViewById(R.id.funnyimage);

        Bundle args = new Bundle();

        this.person = args.getParcelable("Person_List");

        System.out.print("here1");

        if (person != null) {
            Picasso.with(getActivity())
                .load(person.url)
                .placeholder(R.drawable.logo)
                .fit()
                .noFade()
                .into(imageView);
            Log.i("PersonsActivity", String.valueOf(person.url));
        }

        return rootView;

    }
}

Answer 1

删除这些行

Bundle args = new Bundle();

this.person = args.getParcelable("Person_List");

this.person将为null，因为您正试图从空Parcelable获取Bundle。

因此，不会输入。

if (person != null) {

您不需要这些行的原因是因为this.person正确加载onCreate。您不需要使用onCreateView分配它。

使用viewpager，图像不显示

1 个答案: