Question

i am a beginner at java language and i use “text pad”. i have a problem with my simple program. my task is to input 2 values and show the “sum”,”difference”,”product” and “quotient” altogether. (simple right?) in which , here below is the class that supposed to be doing the job of arithmetic. in which is “correct” as i compiled.

public class mathclass
{

    int x;
    int y;
    int total;


    void add ()
    {
        total = x+y;
    }

    void sub ()
    {
        total = x-y;
    }

    void multi ()
    {
        total = x*y;
    }

    void div ()
    {
        total = x/y;
    }

}

And here is the main program that supposed to be the input and output of the program.
my problem here is that i can’t pass the 2 variables (num1 and num2) to “mathclass”
i did research on how to pass 2 variables to a another class. but there is nothing same to mine that i have. i did use some like the putting “private or public” on the variables.
my teacher said to use the BufferedReader for input. and i am having a hard time how to get this program right. (sorry if i had wrong english(if i am wrong. ))

import java.io.*;
public class mathmain
{

    static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

    public static void main(String[]args)throws IOException
    {


        mathclass math1 = new mathclass();

        System.out.print("Enter 1st Number :");
        num1 = Integer.parseInt(br.readLine());
        System.out.println(" ");

        System.out.print("Enter 2nd Number :");
        num2 = Integer.parseInt(br.readLine());
        System.out.println(" ");

        System.out.println(" ");
        System.out.println(" ");
        System.out.println(" ");

        math1.add();
        {
            System.out.print("Sum : ");
            System.out.println(math1.total);
        }
        System.out.println(" ");
        math1.sub();
        {
            System.out.print("Difference : ");
            System.out.println(math1.total);
        }
        System.out.println(" ");

        math1.multi();
        {
            System.out.print("Product : ");
            System.out.println(math1.total);
        }
        System.out.println(" ");
        math1.div();
        {
            System.out.print("Quotient : ");
            System.out.println(math1.total);
        }
    }
}

Answer 1

It’s really not clear what you’re trying to do here. (Why doesn’t add take two arguments for instance?)

Perhaps your after something like this:

// Set up arguments
math1.x = num1;
math1.y = num2;

// Perform the add.
math1.add();
// {                <-- brace completely useless.

// Print the result
System.out.print("Sum : ");
System.out.println(math1.total);
// }                <-- brace completely useless.

However, I would encourage you to use return values and use parameters:

class MathClass {

    public int add(int a, int b) {
        return a + b;
    }

    ...
}

and then use the class like

int sum = math1.add(num1, num2);

System.out.println("Sum: " + sum);