Opening a File from Assets Folder in Android

Opening a File from assets folder in android

These Lines are working perfectly--

InputStream assetInStream=null;

try {
    assetInStream=getAssets().open("icon.png");
    Bitmap bit=BitmapFactory.decodeStream(assetInStream);
    img.setImageBitmap(bit);
} catch (IOException e) {
    e.printStackTrace();
} finally {
    if(assetInStream!=null)
    assetInStream.close();
}

If your image is very big then you should scale your image before decoding it into Bitmap. See How to display large image efficiently

How to access a file from asset/raw directory

Place your text file in the /assets directory under the Android project and use AssetManager class as follows to access it.

AssetManager am = context.getAssets();
InputStream is = am.open("default_book.txt");

Or you can also put the file in the /res/raw directory, from where the file can be accessed by an id as follows

InputStream is = 
context.getResources().openRawResource(R.raw.default_book);

read file from assets

Here is what I do in an activity for buffered reading extend/modify to match your needs

BufferedReader reader = null;
try {
    reader = new BufferedReader(
        new InputStreamReader(getAssets().open("filename.txt")));

    // do reading, usually loop until end of file reading  
    String mLine;
    while ((mLine = reader.readLine()) != null) {
       //process line
       ...
    }
} catch (IOException e) {
    //log the exception
} finally {
    if (reader != null) {
         try {
             reader.close();
         } catch (IOException e) {
             //log the exception
         }
    }
}

EDIT : My answer is perhaps useless if your question is on how to do it outside of an activity. If your question is simply how to read a file from asset then the answer is above.

UPDATE :

To open a file specifying the type simply add the type in the InputStreamReader call as follow.

BufferedReader reader = null;
try {
    reader = new BufferedReader(
        new InputStreamReader(getAssets().open("filename.txt"), "UTF-8")); 

    // do reading, usually loop until end of file reading 
    String mLine;
    while ((mLine = reader.readLine()) != null) {
       //process line
       ...
    }
} catch (IOException e) {
    //log the exception
} finally {
    if (reader != null) {
         try {
             reader.close();
         } catch (IOException e) {
             //log the exception
         }
    }
}

EDIT

As @Stan says in the comment, the code I am giving is not summing up lines. mLine is replaced every pass. That's why I wrote //process line. I assume the file contains some sort of data (i.e a contact list) and each line should be processed separately.

In case you simply want to load the file without any kind of processing you will have to sum up mLine at each pass using StringBuilder() and appending each pass.

ANOTHER EDIT

According to the comment of @Vincent I added the finally block.

Also note that in Java 7 and upper you can use try-with-resources to use the AutoCloseable and Closeable features of recent Java.

CONTEXT

In a comment @LunarWatcher points out that getAssets() is a class in context. So, if you call it outside of an activity you need to refer to it and pass the context instance to the activity.

ContextInstance.getAssets();

This is explained in the answer of @Maneesh. So if this is useful to you upvote his answer because that's him who pointed that out.

open a file outside of assets folder by assetManager

finally, I soloved it by using getClass().getResourceAsStream() instead of assetManager:

public byte[] loadBinAsset(String name) {
    AssetManager assets = context.getResources().getAssets();
    InputStream stream = null;
    try {
        try {
            stream = assets.open(name);
        } catch (IOException e) {
            stream = context.getClass().getResourceAsStream("/" + name);
        }
        return readFully(stream);
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        try {
            if (stream != null) {
                stream.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    return null;
}

How to open and read a text file in my /assets directory?

What you might want to try is use:

AssetManager am = getAssets();
InputStream is;
is = am.open(pathToFile.txt);

Then use a byte[] buffer (get size using is.available(); ) and is.read(buffer)
Don't forget to is.close() after read.

If you're not in an Activity you have to use context.getAssets() in order to get the AssetManager.

Hope that helps you.

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