java - gridview 中加载的图像在滚动时改变其位置

Question

嗨，当滚动 ImageView 更改其位置时，我遇到了此类问题。我在此网站上看到了有关此主题的其他答案，但没有一个对我有帮助。

这是我的类(class):

public class MainActivity extends Activity {
    private GridView grid;
    private GridAdapter adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        grid = (GridView) findViewById(R.id.gridView1);

        Vector<HashMap<String, String>> vData = new Vector<HashMap<String,String>>();

        for (int i=0; i<10; i++) {
            String name = "Name "+ (i+1);
            String desc = "Description "+ (i+1);
            HashMap<String, String> hData = new HashMap<String, String>();
            hData.put("name", name);
            hData.put("desc", desc);

            vData.addElement(hData);
        }

        adapter = new GridAdapter(vData);
        grid.setAdapter(adapter);
        grid.setNumColumns(2);

        File cacheDir = StorageUtils.getCacheDirectory(this);
        ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(this)
            .memoryCacheExtraOptions(480, 800) // default = device screen dimensions
            .discCacheExtraOptions(480, 800, CompressFormat.JPEG, 75, null)
            .threadPoolSize(10) // default
            .threadPriority(Thread.NORM_PRIORITY - 1) // default
            .tasksProcessingOrder(QueueProcessingType.FIFO) // default
            .denyCacheImageMultipleSizesInMemory()
            .memoryCache(new LruMemoryCache(2 * 1024 * 1024))
            .memoryCacheSize(10 * 1024 * 1024)
            .memoryCacheSizePercentage(30) // default
            .discCache(new UnlimitedDiscCache(cacheDir)) // default
            .discCacheSize(80 * 1024 * 1024)
            .discCacheFileCount(100)
            .discCacheFileNameGenerator(new HashCodeFileNameGenerator()) // default
            .imageDownloader(new BaseImageDownloader(this)) // default
            .imageDecoder(new BaseImageDecoder()) // default
            .defaultDisplayImageOptions(DisplayImageOptions.createSimple()) // default
            .build();

        ImageLoader.getInstance().init(config);
    }

    //sub class
    class GridAdapter extends BaseAdapter {
        Vector<HashMap<String,String>> vData;
        GridAdapter(Vector<HashMap<String,String>> vData) {
            this.vData = vData;
        }

        @Override
        public int getCount() {
            // TODO Auto-generated method stub
            return vData.size();
        }

        @Override
        public Object getItem(int index) {
            // TODO Auto-generated method stub
            return vData.elementAt(index);
        }

        @Override
        public long getItemId(int index) {
            // TODO Auto-generated method stub
            return index;
        }

        @Override
        public View getView(int index, View convertView, ViewGroup parent) {
            // TODO Auto-generated method stub
            HashMap<String, String> hData = vData.elementAt(index);

            View v;

            if (convertView == null) {
                LayoutInflater li = getLayoutInflater();
                v = li.inflate(R.layout.grid_element, null);
                // v = getLayoutInflater().inflate(R.layout.grid_element, parent, false);
            } else {
                v = convertView;
            }

            //TextView txtName = (TextView) v.findViewById(R.id.gridText);
            //txtName.setText(hData.get("name"));
            ImageView img = (ImageView) v.findViewById(R.id.gridImg);
            ImageLoader.getInstance().displayImage("http://www.bourax.com/android/wall"+index+".jpg", img);

            return v;
        }
    }
}

我尝试使用支架但出现错误。有什么帮助吗？

Answer 1

@Override
            public View getView(int index, View convertView, ViewGroup parent) {
                // TODO Auto-generated method stub
                HashMap<String, String> hData = vData.elementAt(index);

                View v;
                ImageView img;
                if(convertView == null){

                    LayoutInflater li = getLayoutInflater();
                    v = li.inflate(R.layout.grid_element, null);
                  // v = getLayoutInflater().inflate(R.layout.grid_element, parent, false);
                    img = (ImageView) v.findViewById(R.id.gridImg);
                }else{
                    v = convertView;
                }
                     //TextView txtName = (TextView) v.findViewById(R.id.gridText);
                     //txtName.setText(hData.get("name"));

                ImageLoader.getInstance().displayImage("http://www.bourax.com/android/wall"+index+".jpg", img);


                return v;
            }

相应地更改代码...实际上，当convertView为null时，它需要当前初始化的所有 View 才能在 Activity 上呈现...这就是为什么ImageView需要处于if条件...