Question

我正在使用ViewPager类制作具有水平页面的应用。目前，在正确显示页面时遇到问题。此代码主要来自示例，几乎没有任何修改。我不确定片段“切换”应该如何发生，但我在onCreateView上进行了半工作。现在，当我启动应用程序时，我得到欢迎屏幕，下一页再次欢迎屏幕，然后是第1/2/3页。当“向后移动”时，它会像第3页，第2页，第3页，第2页，第1页那样。可能是mViewPager.getCurrentItem（）存在问题，但我为何无能为力。

    public class MainActivity extends ActionBarActivity {

        SectionsPagerAdapter mSectionsPagerAdapter;
        static ViewPager mViewPager;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);

            getWindow().requestFeature(Window.FEATURE_ACTION_BAR);

            final ActionBar actionBar = getSupportActionBar();
            actionBar.hide(); 
            setContentView(R.layout.activity_main);
            actionBar.setCustomView(R.layout.custom_actionbar);
            actionBar.setDisplayShowTitleEnabled(false);
            actionBar.setDisplayShowCustomEnabled(true); 
            actionBar.setDisplayUseLogoEnabled(false);
            actionBar.setDisplayShowHomeEnabled(false);

            mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

            mViewPager = (ViewPager) findViewById(R.id.pager);
            mViewPager.setAdapter(mSectionsPagerAdapter);

        }

        public class SectionsPagerAdapter extends FragmentPagerAdapter {

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

            @Override
            public Fragment getItem(int position) {
                return PlaceholderFragment.newInstance(position + 1);
            }

            @Override
            public int getCount() {
                return 5;
            }    
        }
        public static class PlaceholderFragment extends Fragment {

            private static final String ARG_SECTION_NUMBER = "section_number";

            public static PlaceholderFragment newInstance(int sectionNumber) {
                PlaceholderFragment fragment = new PlaceholderFragment();
                Bundle args = new Bundle();
                args.putInt(ARG_SECTION_NUMBER, sectionNumber);
                fragment.setArguments(args);
                return fragment;
            }

            public PlaceholderFragment() {
            }

            @Override
            public View onCreateView(LayoutInflater inflater, ViewGroup container,
                    Bundle savedInstanceState) {
                int page = mViewPager.getCurrentItem();
                View rootView;
                switch (page) {
                    case 0: rootView = inflater.inflate(R.layout.welcome_screen, container, false);
                        break;
                    case 1: rootView = inflater.inflate(R.layout.page1, container, false);
                        break;
                    case 2: rootView = inflater.inflate(R.layout.page2, container, false);
                        break;
                    case 3: rootView = inflater.inflate(R.layout.page3, container, false);
                        break;
                    case 4: rootView = inflater.inflate(R.layout.page4, container, false);
                        break;
                    case 5: rootView = inflater.inflate(R.layout.page5, container, false);
                        break;
                    default: rootView = inflater.inflate(R.layout.welcome_screen, container, false);
                }
            }
        }
    }

Answer 1

问题是您根据用户正在查看的视图在ViewPager中创建视图。这显然不是您的意图，因为ViewPager会在认为最适合时生成视图，这与用户正在查看的内容无关。

为了说明这一点，假设应用程序启动，用户将查看第1页.ViewPager准备：

索引编号为0的页面，因为它是当前显示的页面
索引＃1处的页面，因为当用户滑动时，应该可以显示该页面。

但是，由于您根据显示的项目对视图进行了充气，因此这两个视图都将成为欢迎页面：

public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    int page = mViewPager.getCurrentItem();
    View rootView;
    switch (page) {
        ...
    }
}

您应该选择页面索引，因为它是从片段的参数中提供的：

public static class PlaceholderFragment extends Fragment {

    private static final String ARG_SECTION_NUMBER = "section_number";

    private int mPage;

    public static PlaceholderFragment newInstance(int sectionNumber) {
        PlaceholderFragment fragment = new PlaceholderFragment();
        Bundle args = new Bundle();
        args.putInt(ARG_SECTION_NUMBER, sectionNumber);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        Bundle args = getArguments();
        mPage = args.getInt(ARG_SECTION_NUMBER);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView;
        switch (mPage) {
            case 0:
                rootView = inflater.inflate(R.layout.welcome_screen, container, false);
                break;
            case 1:
                rootView = inflater.inflate(R.layout.page1, container, false);
                break;
            case 2:
                rootView = inflater.inflate(R.layout.page2, container, false);
                break;
            case 3:
                rootView = inflater.inflate(R.layout.page3, container, false);
                break;
            case 4:
                rootView = inflater.inflate(R.layout.page4, container, false);
                break;
            case 5:
                rootView = inflater.inflate(R.layout.page5, container, false);
                break;
            default:
                rootView = inflater.inflate(R.layout.welcome_screen, container, false);
                break;
        }
    }
}

Answer 2

简单地传递ArrayList＆lt;整数＆GT;布局xml文件id的内容和扩展PagerAdapter

       public class SectionsPagerAdapter extends PagerAdapter{

        ArrayList<Integer> objects=null;

        public SectionsPagerAdapter(Context ctx,ArrayList<Integer> objects) {

         this.objects = objects;
        }

        @Override
        public Integer getItem(int position) {
            return objects.get(position);
        }

        @Override
        public int getCount() {
            return 5;
        }    




@Override
public View instantiateItem(ViewGroup container, final int position) {

    View convertView = LayoutInflater.from(mContext).inflate(
            this.objects.get(position), null);




    ((ViewPager) container).addView(convertView);

    return convertView;

}

    }

也可以在谷歌上搜索这样的样本。

Answer 3

你只需要一个Bundle来保存你的数据。例如：这是一个实例化的listfragment，它包含两个参数，然后我们需要使用这两个参数来实例化viewpager中的第一页

public static TitleFragment newInstance(int i,int k){
    TitleFragment fragment = new TitleFragment();
    //add Bundle
    PAGE = k;
    NTYPE = i;
    Bundle args = new Bundle();
    args.putInt("PAGE", PAGE);
    args.putInt("NTYPE", NTYPE);
    fragment.setArguments(args);
    Log.d("list", "list" + i);
    return fragment;
}

我们在onCreate Method

中获取数据

@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    int SomeInt = getArguments().getInt("PAGE", 1);
    int someTitle = getArguments().getInt("NTYPE", NTYPE);
    list = getNewList(someTitle,SomeInt);
    myAdapter = new MyAdapter(getActivity(),list,R.layout.news_item);
}

它正常工作。

ViewPager页面错误

3 个答案: