Converting a file in C# into byte array before parsing it into Java [duplicate]

Question

Forgive if this question is incredibly poorly phrased, but I'll do my best to explain what is (to me) a rather complex situation. I am fully aware that I am in way over my head here, experience wise, but I am hoping one of you can help me.

I come to you brighter minds with this, because I am in a complete rut and there appears to be no light at the end of the tunnel.

I have a file I wish converted with C# to a byte array, because the byte array will be sent as an argument into a Java method.

So I thought:

byte[] a = System.IO.File.ReadAllBytes(filePathHere);

Now, this works, and all is peaceful in the world. But the problem arises when i try to send a into my Java method.

The error it throws me when i try to send this to my Java file by means of JSON is:

org.codehaus.jackson.JsonParseException: Numeric value (181) out of range of Java byte

Now, after some (in vain) Googling, I came to the conclusion that C# thinks its being helpful by converting the file into a byte array that contains items with value between 0 and 255.

While Java is expecting to get as an argument for my method is a byte array with values reaching from -128 to 128.

In an ideal world, I would love it if any of you knew how to convert my file C# into a byte array with values reaching from -128 to 128.

However, if this is in fact impossible, I would also be open to, in Java, converting my byte array with value between 0 and 255 to a more desired -128 to 128 format.

Is what I describe impossible, or does someone know how this can be done?

I deeply appreciate any help anyone can provide. The more detailed and noob-friendly, the better!

Would iterating over the c# byte array and converting the byte at that position to a signed int help? I'm not familiar with doing this, but came across this msdn article: BitConverter.ToInt32 Method — JasonWilczak
– JasonWilczak, Commented Apr 28, 2015 at 13:04
and also for reading of the file you can see this : stackoverflow.com/questions/23129598/… — Mohammad Ashfaq
– Mohammad Ashfaq, Commented Apr 28, 2015 at 13:06

Blindy · Accepted Answer · 2015-04-28 13:16:43Z

0

Converting types in C# is relatively trivial:

File.ReadAllBytes(filePathHere).Select(b=>(sbyte)b).ToArray();

As a side note, files are supposed to be made of unsigned bytes, so there's no need for sarcasm ("C# thinks its being helpful"). It's just that Java doesn't have proper data types to deal with it.

answered Apr 28, 2015 at 13:16

Blindy

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Filipe Borges · Accepted Answer · 2015-04-28 13:18:34Z

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This is because Java works with signed numeric primitives only, while c# bytes are unsigned 8 bit integers.

How to solve in the Java side:

You can read it in a integer/short array and then force cast to a byte array, byte by byte.
If you need to work with numbers in the interval [0-255], you should use a integer or short array.

How to solve in C# side:

use a sbyte (signed byte) array [-128 to 127].

edited Apr 28, 2015 at 13:18

answered Apr 28, 2015 at 13:02

Filipe Borges

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