RSA Encryption Using Fast Exponential Technique - Big Integer

I'm currently working on a RSA Encryption using Fast Exponential technique. As the numbers I'm working with will be very huge, I am forced to use BigInteger.

As this is the first time I'm using Big Integer, I encountered quite a number of issues. I'll try my best to explain the errors I'm facing:

1. I had done this step: BigInteger d;

So I'm currently trying to get d = 0;

However, I keep getting an error required: BigInteger, found int.

When I changed it to d = new BigInteger(0) , I get this error:

java:19: error: constructor BigInteger in class BigInteger cannot be applied to given types;

d = new BigInteger(0);
^
required: no arguments
found: int
reason: actual and formal argument lists differ in length

Part of Code:

public class BigFastExponential
{
BigInteger e; // public exponenet: all has this
BigInteger d; // private key: only key owner has this
BigInteger n; // public modulus: all has this

/**
* Create a LongRSA object for a public key holder, with just e and n.
*/
public BigFastExponential(BigInteger public_e, BigInteger public_n)

[Code] ....