Question

我正在尝试制作一个图像寻呼机，看起来我根据我查找过的所有教程都做得正确，但我得到的只是一个空白屏幕。适配器的instantiateItem方法的断点告诉我它正被调用，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，但我仍然看不到任何东西。这是我的代码

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，ViewPagerAdapter.java

公共类ViewPagerAdapter扩展了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));
}

}

为什么我没有看到我的照片有任何明显的明显原因？

Answer 1

destroyItem()需要从容器中删除视图的方式相同，instantiateItem()需要将视图添加到容器中。

添加

    container.addView(itemView);

从instantiateItem()返回之前，您将开始营业。

PagerAdapter始终返回空白

1 个答案: