I have implemented a data structure which is working on my computer and now I am trying to port it into my android application. I open a raw .dat resource and get a InputStream but I need to get a FileInputStream:
FileInputStream fip = (FileInputStream) context.getResources().openRawResource(fileID);
FileChannel fc = fip.getChannel();
long bytesSizeOfFileChannel = fc.size();
MappedByteBuffer mbb = fc.map(FileChannel.MapMode.READ_ONLY, 0L, bytesSizeOfFileChannel);
...
The code above throws the following exception since an InputStream can not be cast to a FileInputStream but that's just what I need:
java.lang.ClassCastException: android.content.res.AssetManager$AssetInputStream cannot be cast to java.io.FileInputStream
All my code is build on using this FileChannel with a FileInputStream so I want to keep using it. Is there a way to go from having an InputStream from context.getResources().openRawResource(fileID) and then convert it into a FileChannel?
Somewhat relevant posts in which I could not find a working solution for my case which android:
How to convert InputStream to FileInputStream
Converting inputStream to FileInputStream?
Using FileChannel to write any InputStream?
A resource isn't a file. Ergo it can't be used as a memory-mapped file. If you have resources that are so enormous they need to be memory-mapped, they probably shouldn't be resources at all. And if they are small, memory mapping brings no advantages.