As usual you can work in pairs.
Your BigInt class will store signed integers. The class must provide the following methods:
|BigInt(String val)||Construct a BigInt object and initialize it with the integer represented by the String. Throw an appropriate exception (BigIntFormatException) if the string does not represent a signed integer (i.e. contains illegal characters)|
|BigInt(BigInt val)||This is the copy constructor. It should make
a deep copy of val. Making a deep copy is not strictly necessary since as
designed a BigInt is immutable, but it is good practice.|
|BigInt(long val)||Construct a BigInt object and
intitialize it wth the value stored in val|
|BigInt add(BigInt val)||Returns a BigInt whose value is (this + val)|
|BigInt multiply(BigInt val)||Returns a BigInt whose value is
|BigInt subtract(BigInt val)||Returns a BigInt whose value is (this - val)|
|BigInt factorial()||Returns a BigInt whose value is
|int compareTo(Object)||Have the BigInt class implement the Comparable interface.|
Override the equals() method from Object.
|String toString()||Returns the decimal representation of this BigInt as a String|
|String toString2s()||Returns the 2's complement representation of this BigInt as a String using the minimum number of digits necessary (e.g. 0 is "0", -1 is "1", 2 is "010", -2 is "10", etc).|
In order to
store the digits, use a doubly-linked list structure; this means a Node
holds a reference to the Node before it and the Node after it.
data to be stored in each Node is one (binary) digit of the number. It is
important to use a double-linked list because different algorithms need
to move in different directions through the data. Don't create a separate LinkedList class that is a copy of what we did in class. Instead, create a Node inner class, and all needed instance fields (such as Node head, etc.) in BigInt.
You are required to store the number in the linked list using the 2's complement representation. A good introduction to 2's complement arithmetic is given on Wikipedia. You must decide which
end of this linked list structure is the least-significant digit. Of course, you are free to store other features
of the BigInt such as its number of digits.
This is going to be a text-based program where the user can input the 4 arithmetic operations (+, -, *, !). Once the program runs, it will print a small prompt to the user and then wait for user input (use the Scanner class). The program will then parse the input, perform the operation, and display the result. The user will type h to get a small help description and q to quit. Here is a sample run. User input is in red:
As we've learned in MVC, this control of the user
interface belongs in a separate class. Make sure to include a main method
so that the program can be run from the command line.
input should be parsed correctly even if the user does not use any spaces (such
as 5+10). Your program should handle input errors,
such as an incorrect operator or a bad number, with helpful error messages.
Your program should not throw any exceptions.