How can I convert a long function into a Biginteger into a string?

Question

I'm trying to change my long variables into BigInteger because I'm storing numbers of the fibonacci series in it and then ultimately turn them into a string. Here is my original code.

public class Fib {
    public static void main(String args[])
    {
        long n1=0,n2=1,n3,i,count = 100;
        System.out.print(n1+" "+n2);//printing 0 and 1

        for(i=2;i<count;++i)//loop starts from 2 because 0 and 1 are already printed
             {
                n3=n1+n2;
                System.out.print(" "+n3);
                n1=n2;
                n2=n3;
            }

        }} :

and I've tried to convert it into a BigInteger AND a string afterwards like this...

public class Fib {
    public static void main(String args[])
    {
        long n1=0,n2=1,n3,i,count = 100;
        BigInteger n1,n2,n3,i,count = BigInteger.valueOf(n1,n2,n3,i,count)
        System.out.print(n1+" "+n2);//printing 0 and 1

        for(i=2;i<count;++i)//loop starts from 2 because 0 and 1 are already printed
             {
                String n3= n1+n2;
                System.out.print(" "+n3);
                n1=n2;
                n2=n3;
            }

        }}

However, an error occurs. I've tried to read the syntax for converting long variables into BigIntegers and BigIntegers into strings and I understand that what I've done is wrong.

However, I can't seem to figure out the right way to implement what I want to do, which is why I've came to StackOverflow to seek help.

If anyone can help me with this, It would be very much appreciated.

Answer 1

The java spec defines rigidly what operators can be applied to what and what it means. Specifically, all the usual mathy operators ( + , - , etc) all apply only to primitive numbers , with the one exception being + which can show up between strings and anything else too, but then it's a completely different thing (string concatenation instead of numeric addition).

They cannot be applied to BigInteger AT ALL - the spec simply doesn't list what that would mean, and java does not have operator overloading.

The direct replacements are methods confusingly named add , subtract , multiply , divide . So,

BigInteger a = BigInteger.ONE;
BigInteger b = BigInteger.ONE;
BigInteger c = a + b; // wrong
BigInteger c = a.add(b); // correct

The better names would have been plus , minus , times , and dividedBy . In the sense that if I write on a blackboard a = b + c , and I ask you to read it out loud, you'd say: "a equals b plus c". Not "a equals b add c". But, it is what it is - just remember, a.add(b) will calculate the sum of a and b and return a brand new BigInteger with the result. It does not add b to a . (BigInteger is immutable; it is not possible to change its value by calling methods on it, or any other way outside of hackery).