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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?
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There is no real difference. FileInputStream extends InputStream , and so you can assign an InputStream object to be a FileInputStream object. In the end, it's the same object, so the same operations will happen. This behavior is called Polymorphism and is very important in Object-Oriented Programming.
Use the below constructor to convert an InputStream to a S3ObjectInputStream : var s3ObjectInputStream = new S3ObjectInputStream(inputStream, null); You can safely use null for the 2nd argument in the constructor ( HttpRequestBase ) as the abort method which uses it, isn't available in the cast InputStream .
FileInputStream class is useful to read data from a file in the form of sequence of bytes. FileInputStream is meant for reading streams of raw bytes such as image data. For reading streams of characters, consider using FileReader. 1.
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.
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