android，画廊视图不显示我的静态图像和崩溃

Question

我想在我的活动中显示画廊视图，但我不知道它发生了什么，它没有显示任何内容并崩溃。

在创建活动方法时，我有：

// initializing gallery view with predefined images
        gallery = (Gallery) findViewById(R.id.gallery);
        gallery.setAdapter(new ImageAdapter(this));
        gallery.setOnItemClickListener(new OnItemClickListener() {
            public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
                Toast.makeText(NewsList.this, "" + position, Toast.LENGTH_SHORT).show();
            }
        });

然后在单独的 java 文件中，我有如下的图像适配器： 公共类 ImageAdapter 扩展 BaseAdapter {

int mGalleryItemBackground;
private Context mContext;

private Integer[] mImageIds = {
        R.drawable.g_adira,
        R.drawable.g_akim,
        R.drawable.g_alyah,
        R.drawable.g_atilia,
        R.drawable.g_awi,
        R.drawable.g_estrange,
        R.drawable.g_hafiz,
        R.drawable.g_hazama,
        R.drawable.g_jac,
        R.drawable.g_kristal,
        R.drawable.g_shila,
        R.drawable.g_stacy
};

public ImageAdapter(Context c) {
    mContext = c;
    TypedArray attr = mContext.obtainStyledAttributes(R.styleable.HelloGallery);
    mGalleryItemBackground = attr.getResourceId(R.styleable.HelloGallery_android_galleryItemBackground, 0);
    attr.recycle();

    Log.i("ImageAdapter", "Gallery setupped successfully.");
}

public int getCount() {
    return mImageIds.length;
}

public Object getItem(int position) {
    return position;
}

public long getItemId(int position) {
    return position;
}

public View getView(int position, View convertView, ViewGroup parent) {
    ImageView imageView = new ImageView(mContext);

    imageView.setImageResource(mImageIds[position]);
    imageView.setLayoutParams(new Gallery.LayoutParams(150, 120));
    imageView.setScaleType(ImageView.ScaleType.FIT_XY);
    imageView.setBackgroundResource(mGalleryItemBackground);

    Log.i("ImageAdapter", "Position:" + position);

    return imageView;
}

}

画廊的XML代码：

<?xml version="1.0" encoding="utf-8"?>

<Gallery 
    xmlns:android="http://schemas.android.com/apk/res/android" 
    android:id="@+id/gallery"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true" />

我不知道为什么它不起作用。在 logcat 中，我看到我的日志放在构造函数中，因为我得到空指针异常，并且引用的是“gallery.setAdapter(new ImageAdapter(this));”

任何建议表示赞赏。谢谢

Answer 1

检查此代码

public class GalleryActivity extends Activity {

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

    Gallery gallery = (Gallery) findViewById(R.id.gallery);
    gallery.setAdapter(new ImageAdapter(this));

    gallery.setOnItemClickListener(new OnItemClickListener() {
        public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
            Toast.makeText(GalleryActivity.this, "" + position, Toast.LENGTH_SHORT).show();
        }
    });
}
    class ImageAdapter extends BaseAdapter {
        int mGalleryItemBackground;
        private Context mContext;

        private Integer[] mImageIds = {
                 R.drawable.sample_1,
                 R.drawable.sample_2,
                 R.drawable.sample_3,
                 R.drawable.sample_4,
                 R.drawable.sample_5,
                 R.drawable.sample_6,
                 R.drawable.sample_7

        };

        public ImageAdapter(Context c) {
            mContext = c;
            TypedArray attr = mContext.obtainStyledAttributes(R.styleable.HelloGallery);
            mGalleryItemBackground = attr.getResourceId(
                    R.styleable.HelloGallery_android_galleryItemBackground, 0);
            attr.recycle();
        }

        public int getCount() {
            return mImageIds.length;
        }

        public Object getItem(int position) {
            return position;
        }

        public long getItemId(int position) {
            return position;
        }

        public View getView(int position, View convertView, ViewGroup parent) {
            ImageView imageView = new ImageView(mContext);

            imageView.setImageResource(mImageIds[position]);
            imageView.setLayoutParams(new Gallery.LayoutParams(150, 100));
            imageView.setScaleType(ImageView.ScaleType.FIT_XY);
            imageView.setBackgroundResource(mGalleryItemBackground);

            return imageView;
        }
    }
}