ViewPager与FragmentPagerAdapter不显示内容 [英] ViewPager with FragmentPagerAdapter does not show content

问题描述

我试图使用片段，ViewPager和放大器;合。从Android支持库V4。片段似乎当我听页面变化事件的寻呼机，但内容是不可见的滚动。我基本上已经是：

I'm trying to use the Fragment, ViewPager & co. from the Android support library v4. Fragments seem to scroll when I listen to page change events from the pager but the content is not visible. What I basically have is:

一个FragmentActivity：

A FragmentActivity:

public class MyActivity extends FragmentActivity
{
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        FragmentPagerAdapter fpa = new MyPagerAdapter(this, createFragments());

        ViewPager vp = (ViewPager) findViewById(R.id.pager);
        vp.setAdapter(fpa);
    }

    private List<Fragment> createFragments() {
        List<Fragment> list = new ArrayList<Fragment>();
        list.add(Fragment.instantiate(this, First.class.getName()));
        list.add(Fragment.instantiate(this, Second.class.getName()));
        list.add(Fragment.instantiate(this, Third.class.getName()));

        return list;
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {

    }

一个FragmentPagerAdapter：

A FragmentPagerAdapter:

public class MyPagerAdapter extends FragmentPagerAdapter {
    private List<Fragment> fragments;

    public MyPagerAdapter(FragmentActivity activity, List<Fragment> fragments) {
        super(activity.getSupportFragmentManager());
        this.fragments = fragments;
    }

    @Override
    public Fragment getItem(int i) {
        return fragments.get(i);
    }

    @Override
    public int getCount() {
        return fragments.size();
    }

    @Override
    public boolean isViewFromObject(View view, Object o) {
        return view.equals(o);
    }

}

和三个片段看起来是这样的：

And three Fragments that look like this:

public class First extends Fragment {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

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

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

和他们有这样的布局：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="fill_parent"
              android:layout_height="fill_parent">
    <TextView android:layout_height="fill_parent"
              android:layout_width="fill_parent"
              android:text="First Fragment"
              android:id="@+id/firstText"/>
</LinearLayout>

我原来忘了加上主要布局，这里说到：

I originally forgot to add the main layout, here it comes:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
    <android.support.v4.view.ViewPager
            android:id="@+id/pager"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:layout_width="fill_parent"/>
</LinearLayout>

我会AP preciate如果有人能告诉我什么，我做错了。

I would appreciate if someone can tell me what I am doing wrong.

推荐答案

这是因为你已经在覆盖 isViewFromObject MyPagerAdapter 。

This is because you have overridden isViewFromObject in MyPagerAdapter.

FragmentPagerAdapter 手柄 isViewFromObject ，所以你不应该忽略它。

FragmentPagerAdapter handles isViewFromObject, so you shouldnt override it.

至于我，我估计大多数游客到这个帖子开始一个基本的 PagerAdapter ，他们意识到他们需要页面片段，并改变了他们的基类没有意识到后果。不幸的，但我不能批评Android团队这一点。

As with me, I reckon most visitors to this post started with a basic PagerAdapter, them realised they needed to page fragments and changed their base class without realising the consequences. Unfortunate, but I couldn't criticise the Android team for this.

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