new to java, help simple project

using the class java.lang.BigInteger that handles large integers, make a
class BigInt that can do calculations with non-negaitve numbers. i must use
the following....

•A data structure to represent large numbers: for example, a string or an
array of digits in a number
•public BigInt(String val)
A constructor that uses a string representation of the integer for
initialization. The string may contain leading zeros. Do not forget that
zero is a valid number.
•public void display()
A method to write numbers. Do not write leading zeros, but if the number
consists of all zeros, write a single zero.
•public BigInt add(BigInt val)
A method that returns the sum of val and the instance of BigInt that invokes
add.

thanks for the help!

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