android - 上传图片步骤中，把选中的图片存本地的方法耗时如何处理？

Question

for (int i=0;i<paths.size();i++) {
        Bitmap bitmap = ImageCompressUtil.compressBySize(paths.get(i), 1000, 1000);
        ImageTools.savePhotoToSDCard(bitmap, Constants.MyAvatarDir, i + "");
        newPaths.add(Constants.MyAvatarDir + i + ".jpg");
    }

代码如上，paths为一个选中图片地址的list，现在我遍历他，进行压缩，以1、2、3数字来命名，并存入本地，在将压缩后的地址存入newpaths中，传入adapter显示。

现在出现了个问题，选中的图片还没来得及存入本地，覆盖原本以1、2、3数字来命名的图片，就传入adapter中，所以显示的图片是上次存的图片。

我的解决方法是延迟500ms后才传入adapter，显然这不是最好的方法，望大神们提供更加完美的解决方案。

Answer 1

It depends on where you setAdapter and notifyDataSetChanged. If it is in a different thread than the above code block, your situation may occur. The above code block should be executed before calling the adapter refresh method. This is Be sure.

Answer 2

You can use the observer pattern and pass a Listener to your ImageTools.savePhotoToSDCard method,

Interface OnSavePhotoToSDCardListener {
    void onSaveSucceed();
    void onSaveFailed();
}

So the code should be changed to this

for (int i=0;i<paths.size();i++) {
        final int token = i;
        Bitmap bitmap = ImageCompressUtil.compressBySize(paths.get(i), 1000, 1000);
        ImageTools.savePhotoToSDCard(bitmap, Constants.MyAvatarDir, token + "", new OnSavePhotoToSDCardListener() {
            @Override
            public void onSaveSucceed() {
                newPaths.add(Constants.MyAvatarDir + token + ".jpg");
            }
            
            @Override
            public void onSaveSucceed() {
                //do something
            }
        });
    }

Of course, it is recommended that you correctly handle the timing of setAdapter and adapter.notifyDataSetChanged() calls.