Check for file existence in androids assets folder?

Question

My app has .txt files in subdirectories in the assets folder. It reads those .txt files and puts them in a textview. It\'s working great and no problems.

Should I be

Answer 1

You may be concerned that the file have been removed and the apk resigned

You can check using:

Arrays.asList(getResources().getAssets().list("")).contains("myFile")

Answer 2

Ideally after apk is built, nobody can remove any assets from it, but if someone decompiled it and recompiles than it may be possible.

Though for other scenarios also when an asset is not present in apk at Runtime, we can check the existence of asset.

In our app, we have a provision to build app using gradle, ant and eclipse, and for each build mechanism some of our assets file are bundled in apk and some are not, so to identify if any asset file is present in current build apk at runtime,

we do this as follows:

private boolean isAssetExists(String pathInAssetsDir){
    AssetManager assetManager = AppContext.get().getResources().getAssets();
    InputStream inputStream = null;
    try {
        inputStream = assetManager.open(pathInAssetsDir);
        if(null != inputStream ) {
           return true;
        }
    }  catch(IOException e) {
        e.printStackTrace();
    } finally {
        try {
            inputStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }  
    return false;
}

Answer 3

if you really want to check for the file existence:

AssetManager mg = getResources().getAssets();
InputStream is = null;
try {
  is = mg.open(pathInAssets);
  //File exists so do something with it
} catch (IOException ex) {
  //file does not exist
} finally {
  if (is != null) {
    is.close();
  }
}

If your file is located in assets/folder/file.ext, then pathInAssets would be "folder/file.ext"

Answer 4

I think you should be OK. From having a root around in my phone I can't see any way of deleting the assests without deleting the app as it all seems to be wrapped up in the .apk file. You can do it but I think you need to be rooted or use adb.

I would personally surround any reading/writing with a try/catch block anyway, just to be safe.

Answer 5

Yes and No.

A normal user would not be able to delete them, but a user on a rooted phone who doesn't know what they're doing… that's a different situation.

If you ask me, the extra code is not needed. Also if you try and open a file that doesn't exist, you will get an exception thrown at some point, catch that and display a dialog if you really want to.

Answer 6

AssetManager am = getAssets();

    try {
        List<String> mapList = Arrays.asList(am.list("path/in/assets/folder"));

        if (mapList.contains("file_to_check")) {
            Log.e("ERROR", "exists");
        } else {
            Log.e("ERROR", "not exists");
        }
    } catch ( IOException ex){
        ex.printStackTrace();
    }

Convert to function or method can be easy ;)