Answer:
public class Calculator {
        public double add(int a, int b){
        return a+b;
    }
    public double substract(int a, int b){
        return a-b;
    }
    public double multiply(int a, int b){
        return a*b;
    }
    public double divide(int a, int b){
        if(b>0){
            return a/b;
        }
        else{
            System.out.println("Cannot divide by zero");
        }
        return -1;
    }    
}
Explanation:
- Using Java Programming Language, the class Calculator is created. There are no fields (Instance variables) and no constructors since these are not required by the question.
- Four methods (functions) are created:  add, substract, multiply and divide as specified in the question.
- Note the use of the if statement in the divide() to handle case of illegal division (by 0)