How to get access to raw resources that I put in res folder?

InputStream raw = context.getAssets().open("filename.ext");

Reader is = new BufferedReader(new InputStreamReader(raw, "UTF8"));

For raw files, you should consider creating a raw folder inside res directory and then call getResources().openRawResource(resourceName) from your activity.

In some situations we have to get image from drawable or raw folder using image name instead if generated id

// Image View Object 
        mIv = (ImageView) findViewById(R.id.xidIma);
// create context Object for  to Fetch  image from resourse 
Context mContext=getApplicationContext();

// getResources().getIdentifier("image_name","res_folder_name", package_name);

// find out below example 
    int i = mContext.getResources().getIdentifier("ic_launcher","raw", mContext.getPackageName());

// now we will get contsant id for that image       
        mIv.setBackgroundResource(i);