Question

我遇到的问题是我ArrayIndexOutOfBound photoViewAttacherList.get(position)。现在我可以通过捕获错误轻松处理，但我无法理解为什么它发生在最初的位置。这是适配器的代码。这很奇怪，因为我在new PhotoViewAttacher函数中添加了instantiate，这将为每个添加的新项目调用。

public class FullImagePagerAdaptor extends PagerAdapter {


private final LayoutInflater inflater;
private final ArrayList<String> urls;
private final Context context;
private final ArrayList<String> descriptions;
private ArrayList<PhotoViewAttacher> photoViewAttacherList;
private TogglePagingListener togglePagingListener;

public FullImagePagerAdaptor(Context context, ArrayList<String> urls, ArrayList<String>
        descriptions, TogglePagingListener togglePagingListener) {
    inflater = (LayoutInflater) context
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    this.urls = urls;
    this.context = context;
    this.descriptions = descriptions;
    photoViewAttacherList = new ArrayList<>();
    this.togglePagingListener = togglePagingListener;
}

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

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

@Override
public Object instantiateItem(ViewGroup container, final int position) {

    View v = inflater.inflate(R.layout.fragment_full_image, container, false);
    TextView description = (TextView) v.findViewById(R.id.txt_full_image_description);
    ProgressBar progressBar = (ProgressBar) v.findViewById(R.id.progress_bar_full_image);
    ImageView imageView = (ImageView) v.findViewById(R.id.full_image_view);
    if (descriptions != null && descriptions.get(position) != null) {
        description.setText(descriptions.get(position));
    }

    Log.d("sg","Instantiating Pager:with position" + position);

    ImageUtility.loadImage(context, urls.get(position),
            GlobalVariables.IMAGE_TYPE.URL, 0, 0,
            imageView, progressBar);
    photoViewAttacherList.add(new PhotoViewAttacher(imageView));


    // THIS IS WHERE ARRAYINDEXOUTOFBOUND EXCEPTION IS GETTING RAISED
    photoViewAttacherList.get(position).setOnMatrixChangeListener(new PhotoViewAttacher.OnMatrixChangedListener() {
        @Override
        public void onMatrixChanged(RectF rect) {
            if(isImageZoomed(position))
                togglePagingListener.disablePaging();
            else
                togglePagingListener.enablePaging();
        }
    });
    container.addView(v);
    return v;
}

@Override
public void destroyItem(ViewGroup container, int position, Object object) {
    photoViewAttacherList = null;
    container.removeView((View) object);
}

public boolean isImageZoomed(int pos) {
    return checkZoom(pos) != 1.0;
}

public float checkZoom(int pos){
    return photoViewAttacherList.get(pos).getScale();
}

public interface TogglePagingListener {
    public void enablePaging();
    public void disablePaging();
}

Answer 1

从您的代码中我了解一件事，您希望将新的PhotoViewAttacher对象添加到现有列表中，并为该对象添加一个侦听器setOnMatrixChangeListener。为此，您将在列表中添加该对象，然后从列表中再次访问该对象，而不是您可以创建一个对象并添加到列表，并且可以添加事件侦听器到同一对象。这是一个干净的方法
还应重新计算position以确切知道元素的插入位置，但这是final，因此您无法对其进行更改，因此请为其声明一个新变量。

<强>段：

    PhotoViewAttacher photoObj =  new PhotoViewAttacher(imageView);
    photoViewAttacherList.add(photoObj);

    final int newPositionInserted = photoViewAttacherList.size() - 1; //Recalculating the position here  to know exactly where the object was added
    // Here you can use the object which was created so you do not need to worry about the index also
    photoObj.setOnMatrixChangeListener(new PhotoViewAttacher.OnMatrixChangedListener() {
        @Override
        public void onMatrixChanged(RectF rect) {
            if(isImageZoomed(newPositionInserted))
                togglePagingListener.disablePaging();
            else
                togglePagingListener.enablePaging();
        }
    });

全球Arraylist指数超出范围问题

1 个答案: