PagerAdapter 总是返回空白

问题描述

我正在尝试制作一个图像寻呼机，看起来我已经按照我查找的所有教程正确地完成了它，但我得到的只是一个空白屏幕.适配器的 instantiateItem 方法上的断点告诉我它正在被调用，并且所有正确的信息都被设置到视图中，并且滑动甚至可以工作，但我仍然什么也没看到.这是我的代码

I'm trying to make an image pager and it looks like I've done it correct according to all the tutorials that I've looked up, but all I get is a blank screen. A breakpoint on the adapter's instantiateItem method tells me that it is being called and all the right information is getting set into the views, and swiping even works, but I still don't see anything. Here is my code

activity_photos.xml

<RelativeLayout> // I'm not including that code, irrelevant.
<android.support.v4.view.ViewPager
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/imagePager"
    android:background="@android:color/black"/>
</RelativeLayout>

viewpager_itemx.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:orientation="vertical"
              android:layout_width="match_parent"
              android:layout_height="match_parent">

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:id="@+id/imageView"/>

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/imageLabel"
        android:textColor="@android:color/white"/>
</LinearLayout>

PhotosActivity.java

    final String[] images = getResources().getStringArray(R.array.tips_images);
    final String[] labels = getResources().getStringArray(R.array.tips_text);

    final ViewPager viewPager = (ViewPager) findViewById(R.id.imagePager);
    final ViewPagerAdapter viewPagerAdapter = new ViewPagerAdapter(PhotoTipsActivity.this, images, labels);

    viewPager.setAdapter(viewPagerAdapter);

最后是 ViewPagerAdapter.java

and finally, ViewPagerAdapter.java

公共类 ViewPagerAdapter 扩展 PagerAdapter {

public class ViewPagerAdapter extends PagerAdapter {

private Context context;
private String[] images;
private String[] labels;

public ViewPagerAdapter(Context context, String[] images, String[] labels) {
    this.context = context;
    this.images = images;
    this.labels = labels;
}

@Override
public int getCount() {
    return images.length;
}

@Override
public boolean isViewFromObject(View view, Object object) {
    return view == object;
}

@Override
public Object instantiateItem(ViewGroup container, int position) {
    final View itemView = LayoutInflater.from(context).inflate(R.layout.viewpager_item, container, false);
    final ImageView imageView = (ImageView) itemView.findViewById(R.id.imageView);
    final TextView imageLabel = (TextView) itemView.findViewById(R.id.imageLabel);

    // Get drawable image.
    final int imageId = context.getResources().getIdentifier(images[position], "drawable", context.getPackageName());

    imageView.setImageResource(imageId);
    imageLabel.setText(labels[position]);

    return itemView;
}

@Override
public void destroyItem(ViewGroup container, int position, Object object) {
    container.removeView(((LinearLayout) object));
}

}

我没有看到我的图像有什么明显的原因吗?

Any blatantly obvious reason why I'm not seeing my images?

推荐答案

同理destroyItem()需要从容器中移除视图，instantiateItem()需要将视图添加到容器中.

The same way destroyItem() needs to remove the view from the container, instantiateItem() needs to add the view to the container.

只需添加

    container.addView(itemView);

在从 instantiateItem() 返回之前，您将开始做生意.

before returning from instantiateItem() and you'll be in business.

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