from byteArray to bigInteger

Question

how to convert a byteArray to bigInteger? it's important to say than my bytearray is not the ordinay byte[].. its a class in my project. basically i have an array of 256 bytes and i need to represent it as BigInteger in order to perform a calculation .

the code looks like this:

//this is how i get my information in byteArray

 ByteArray modulus = (ByteArray)inParamsList.getParameterType("modulus");

//this is the line that i get an exception for. it happens because the "toString" doesn't actully converts it to string

 BigInteger modulusInBig = new BigInteger(modulus.toString());

i would be very happy to get some answers! i lookes all over the internet already...

How should the bytes in the array be interpreted for conversion to a number? — Matt Ball
– Matt Ball, Commented Nov 4, 2012 at 16:00
@MattBall that is already defined by the constuctors of BigInteger. — weston
– weston, Commented Nov 4, 2012 at 16:23
@weston not necessarily. It depends on how the OP is currently representing the number in a byte array. There is more than one way to interpret a sequence of bits. — Matt Ball
– Matt Ball, Commented Nov 4, 2012 at 16:27

weston · Accepted Answer · 2012-11-04 16:03:34Z

2

Modify your ByteArray class to provide a toArrayByte() method, returning byte[] then:

BigInteger modulusInBig = new BigInteger(modulus.toArrayByte());

answered Nov 4, 2012 at 16:03

weston

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2 Comments

user1584314 Over a year ago

you wrote: "Modify your ByteArray class to provide a toArrayByte() method, returning byte[]"... this it exacly my problem.. i'm not sure how to do that..

weston Over a year ago

Then we need to see your ByteArray class. Lots of people have asked for that.

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