different results when converting int to byte array - .NET vs Java

Question

I am trying to send data from a java client to a c# server and having trouble converting int to byte array.

when i am converting the number 8342 with c# using this code:

BitConverter.GetBytes(8342)

the result is: x[4] = { 150, 32, 0, 0 }

with java i use:

ByteBuffer bb = ByteBuffer.allocate(4); 
bb.putInt(8342); 
return bb.array();

and here the result is: x[4] = { 0, 0, 32, -106 }

Can someone explain? I am new to java and this is the first time i see negative numbers in byte arrays.

manojlds · Accepted Answer · 2011-05-07 11:21:53Z

9

You have to change endianess:

 bb.order(ByteOrder.LITTLE_ENDIAN)

Java stores things internally as Big Endian, while .NET is Little Endian by default.

Also there is difference in signed and unsigned between Java and .NET. Java uses signed bytes, C# uses unsigned. You will have to change that as well.

Basically, that is why you are seeing -106 ( 150 - 256 )

You will have to do something like the utility method below:

public static void putUnsignedInt (ByteBuffer bb, long value)
    {
       bb.putInt ((int)(value & 0xffffffffL));
    }

Note that value is long.

edited May 7, 2011 at 11:21

answered May 6, 2011 at 23:59

manojlds

303k66 gold badges482 silver badges426 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

Voo Over a year ago

Well ByteBuffer is documented (so reading the jdoc would've helped) to use BigEndian as default, but that's actually an interesting question, does Java define the used ByteOrder? I doubt it - would be a much to high performance hit and not noticeable anyways (except when writing output and we can convert it there easily according to the documentation)

Bala R Over a year ago

I think now the output will be -106, 32, 0, 0

Idan Over a year ago

After the added line: ByteOrder.LITTLE_ENDIAN the array really changed it's orders. For the c# server to understand it i need to change the byte array to be unsigned. Is there a way to tell the ByteBuffer to do that or i need to change each byte?

Gabe Over a year ago

@idan: -106 and 150 are the same byte; they just convert differently to strings or larger integers. Since Java doesn't have a way to represent unsigned bytes, there's no way to represent 150 as a byte in Java.

Collectives™ on Stack Overflow

different results when converting int to byte array - .NET vs Java

1 Answer 1

4 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related