Java read unsigned int, store, and write it back

Question

I need to read an unsigned int from a quicktime file, and write it back to another quicktime file.

Currently I read the unsigned int into a Long but while writing it back I never managed to write the exact number back in 4 bytes as unsigned int. The long has the correct value that I need to write back. (eg 3289763894 or 370500) I am unable to even read the write a number smaller then Integer.MAX_VALUE (eg 2997).

I am using the following methods to write the value back

 public void writeUInt32(long uint32,DataOutputStream stream) throws IOException {
    writeUInt16((int) (uint32 & 0xffff0000) >> 16,stream);
    writeUInt16((int) uint32 & 0x0000ffff,stream);
    }


public void writeUInt16(int uint16,DataOutputStream stream) throws IOException {
        writeUInt8(uint16 >> 8, stream);
        writeUInt8(uint16, stream);
    }


    public void writeUInt8(int uint8,DataOutputStream stream) throws IOException {
        stream.write(uint8 & 0xFF);
    }

Any help would be appreciated.

Answer 1

Just write your long casted to int. I checked:

PipedOutputStream pipeOut = new PipedOutputStream ();
PipedInputStream pipeIn = new PipedInputStream (pipeOut);
DataOutputStream os = new DataOutputStream (pipeOut);

long uInt = 0xff1ffffdL;

System.out.println ("" + uInt + " vs " + ((int) uInt));
os.writeInt ((int) uInt);
for (int i = 0; i < 4; i++) System.out.println (pipeIn.read ());

uInt = 0x000ffffdL;
System.out.println ("" + uInt + " vs " + ((int) uInt));
os.writeInt ((int) uInt);
for (int i = 0; i < 4; i++) System.out.println (pipeIn.read ());

Output is

4280287229 vs -14680067
255
31
255
253
1048573 vs 1048573
0
15
255
253

as expected

Answer 2

If you only want to read, store and rewrite it, then you can just use int. More general: as long as you do not interpret the bits you can just read, store and write them without caring about the intended interpretation of the bits.