I am attempting to convert a program that reads a binary file in C++ to java. The file is in little-endian.
fread(n, sizeof (unsigned), 1, inputFile);
The snippet above of c++ reads 1 integer into the integer variable 'n'.
I am currently using this method to accomplish the same thing:
public static int readInt(RandomAccessFile inputStream) throws IOException {
int retVal;
byte[] buffer = new byte[4];
inputStream.readFully(buffer);
ByteBuffer wrapped = ByteBuffer.wrap(buffer);
wrapped.order(ByteOrder.LITTLE_ENDIAN);
retVal = wrapped.getInt();
return retVal;
}
but this method sometimes differs in its result to the c++ example. I haven't been able to determine which parts of the file cause this method to fail, but I know it does. For example, when reading one part of the file my readInt method returns 543974774 but the C++ version returns 1.
Is there a better way to read little endian values in Java? Or is there some obvious flaw in my implementation? Any help understanding where I could be going wrong, or how could I could read these values in a more effective way would be very appreciated.
Update: I am using RandomAcccessFile because I frequently require fseek functionality which RandomAccessFile provides in java
543974774 is, in hex, 206C6576.
There is no endianness on the planet that turns 206C6576 into '1'. The problem is therefore that you aren't reading what you think you're reading: If the C code is reading 4 bytes (or even a variable, unknown number of bytes) and turns that into '1', then your java code wasn't reading the same bytes - your C code and java code is out of sync: At some point, your C code read, for example, 2 bytes, and your java code read 4 bytes, or vice versa.
The problem isn't in your readInt method - that does the job properly every time.