java - 如何更改 ViewPager 中幻灯片上的 fragment 内容？

Question

我已经实现了 THIS在我的 Activity 中，它工作得很好，但每次用户在屏幕上滑动手指时，我都想更改 fragment 的内容。现在它显示相同的文本而不考虑幻灯片(从左到右或从右到左)。我该如何处理？我知道我在这里遗漏了极小的一部分，但我无法理解发生了什么。我应该在哪里添加监听器并处理操作？

这是我目前所拥有的:

public class ViewrerAct extends FragmentActivity {

    private static final int NUM_PAGES = 5;
    private ViewPager mPager;
    private PagerAdapter mPagerAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_screen_slide);

        // Instantiate a ViewPager and a PagerAdapter.
        mPager = (ViewPager) findViewById(R.id.pager);
        mPagerAdapter = new ScreenSlidePagerAdapter(getSupportFragmentManager());
        mPager.setAdapter(mPagerAdapter);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.bulgarian_sayings, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    /**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment extends Fragment {

        public PlaceholderFragment() {
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            View rootView = inflater.inflate(
                    R.layout.fragment_viewer, container, false);
            return rootView;
        }
    }

    private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {
        public ScreenSlidePagerAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public Fragment getItem(int position) {
            System.out.println("inside!");
            return new ScreenSlidePageFragment();
        }

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

和

public class ScreenSlidePageFragment extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        ViewGroup rootView = (ViewGroup) inflater.inflate(
                R.layout.fragment_viewer, container, false);

        return rootView;
    }
}

Answer 1

您应该发布 ScreenSlidPagerAdapter 的代码。

但是，您需要重写寻呼机适配器的 setPrimaryItem 方法，每次滑动寻呼机并更改显示的页面时都会调用该方法。

例如:

   @Override
public void setPrimaryItem(ViewGroup container, int position, Object object) {
    super.setPrimaryItem(container, position, object);
    currentPage = position;
}

您可以将字符串存储在数组中并将其传递给适配器，在适配器内部您可以根据所选位置更改 fragment 的内容。

如果需要更合适的示例，也可以使用 Post 寻呼机适配器。

在您的情况下，假设您只想显示不同的测试，您可以简单地将字符串数组传递给 ex 的适配器:

   private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {
        String[] displayText;
        public ScreenSlidePagerAdapter(FragmentManager fm,String[] displayText) {
            super(fm);
            this.displayText=displayText;
        }

        @Override
        public Fragment getItem(int position) {
            System.out.println("inside!");
            ScreenSlidePageFragment fragment = new ScreenSlidePageFragment(); 
            fragment.setText(displayTest[position]);
            return fragment;
        }

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

您的 Fragment 类将更改为:

public class ScreenSlidePageFragment extends Fragment {
    private String text;    
    public void setText(String text){

     this.text=text;
     }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        ViewGroup rootView = (ViewGroup) inflater.inflate(
                R.layout.fragment_viewer, container, false);
        ((TextView)rootView.findViewById(textViewId)).setText(Text);
        return rootView;
    }
}