在片段内创建图像的GridView [英] Create a GridView of images inside a Fragment

问题描述

我试图在片段内部创建一个网格视图。我已经实现了适配器类和相应的重写方法。但在运行时会引发一行异常：

  gridView.setOnItemClickListener（this）; 
  

声明gridView对象是一个NULL指针。

这是我的代码（非常类似于 Google Sample ）：

pre $ public static class OcrOverrideFragment extends Fragment implements AdapterView.OnItemClickListener {

// The Adapter网格视图的类
public class ImageAdaptor extends BaseAdapter {

private Context mContext;

public ImageAdaptor（Context c）
{
mContext = c;

}

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

public Object getItem（int position）{
return null;

$ b public int getCount（）{

try
{
String [] f = mContext.getAssets（）。list OcrSampleImages）;
返回f.length;
}
catch（IOException e）
{
LogUtil.d（TAG，OCR_OVERRIDE given+ e）;
}
返回0;
}

//对于网格中的每个项目，此方法将被称为
public View getView（int position，View convertView，ViewGroup parent）{

ImageView imageView = null;

尝试
{
String [] f = mContext.getAssets（）。list（OcrSampleImages）;

if（convertView == null）{
imageView = new ImageView（getContext（））;
imageView.setLayoutParams（new GridView.LayoutParams（85，85））;
imageView.setScaleType（ImageView.ScaleType.CENTER_CROP）;
imageView.setPadding（8，8，8，8）;
}
else {
imageView =（ImageView）convertView;


//为每个网格项目设置适当的图像
imageView.setImageBitmap（getBitmapFromAsset（OcrSampleImages+ System.getProperty（file.separator）+ f [位置]））;

$ b catch（IOException e）
{
LogUtil.d（TAG，OCR_OVERRIDE given+ e）;
}

return imageView;
}
} //结束ImageAdaptor类
$ b @覆盖
public View onCreateView（LayoutInflater inflater，ViewGroup容器，Bundle savedInstanceState）{

View v = inflater.inflate（R.layout.ocr_override，container，false）;

GridView gridView =（GridView）（getActivity（）。findViewById（R.id.ocrgridview））;
gridView.setAdapter（new ImageAdaptor（v.getContext（）））;
gridView.setOnItemClickListener（this）;

return v;
}

@Override
public void onItemClick（AdapterView<？> adaptorView，View v，int i，long l）
{
//执行细节unncessary

}


解决方案

Change this line

pre $ GridView gridView =（GridView）（getActivity（）。findViewById（R.id.ocrgridview））;

至

  GridView gridView =（GridView）v.findViewById（R.id.ocrgridview）; //注意v不是活动
  

I am trying to create a Grid View inside a Fragment. I have implemented the adaptor class and the respective overriden methods. But while running it throws an exception in the line :

gridView.setOnItemClickListener (this);

stating that the gridView object is a NULL pointer.

Here is my code (very similar to Google Sample) :

public static class OcrOverrideFragment extends Fragment implements AdapterView.OnItemClickListener {

    // The Adaptor Class for the grid view
    public class ImageAdaptor extends BaseAdapter{

        private Context mContext;

        public ImageAdaptor (Context c)
        {
            mContext = c;

        }

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

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

        public int getCount (){

            try
            {
                String[] f = mContext.getAssets().list("OcrSampleImages");
                return f.length;
            }
            catch (IOException e)
            {
                LogUtil.d (TAG,"OCR_OVERRIDE gave " + e);
            }
            return 0;
        }

        // For each of the items in the grid, this method will be called
        public View getView(int position, View convertView, ViewGroup parent) {

            ImageView imageView = null;

            try
            {
                String[] f = mContext.getAssets().list("OcrSampleImages");

                if (convertView == null) {
                    imageView = new ImageView(getContext());
                    imageView.setLayoutParams(new GridView.LayoutParams(85, 85));
                    imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
                    imageView.setPadding(8, 8, 8, 8);
                }
                else {
                    imageView = (ImageView) convertView;
                }

                // Setting the appropriate image for each gird item
                imageView.setImageBitmap(getBitmapFromAsset("OcrSampleImages"+System.getProperty("file.separator")+f[position]));

            }
            catch (IOException e)
            {
                LogUtil.d (TAG,"OCR_OVERRIDE gave " + e);
            }

            return imageView;
        }
    } // End Of ImageAdaptor Class

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        View v = inflater.inflate(R.layout.ocr_override, container, false);

            GridView gridView = (GridView) (getActivity().findViewById(R.id.ocrgridview));
            gridView.setAdapter(new ImageAdaptor(v.getContext()));
            gridView.setOnItemClickListener (this);

        return v;
    }

    @Override
    public void onItemClick (AdapterView<?> adaptorView,View v,int i,long l)
    {
        // Implementation details unncessary

    }

解决方案

Change this line

GridView gridView = (GridView) (getActivity().findViewById(R.id.ocrgridview));

To

GridView gridView = (GridView) v.findViewById(R.id.ocrgridview); //Note "v" not activity

这篇关于在片段内创建图像的GridView的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！