Add/subtract

Write add and subtract methods.

The add method

The first method of the calculator is add. It takes two ints, sums them and returns the result. It is static, so it is called directly, not via a class name.

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

You can call it in main as add(5, 3); the result is 8. The same structure works for subtract: return a - b;.

Both methods return int because we work with integers.

Exercise Add add and subtract methods

Add static int add(int a, int b) and static int subtract(int a, int b) methods to the existing Main class. add returns a + b, subtract returns a - b. Call both in main and print with println; keep the existing println call.

Show example solution

public class Main {
    static int add(int a, int b) {
        return a + b;
    }
    static int subtract(int a, int b) {
        return a - b;
    }
    public static void main(String[] args) {
        System.out.println("Calculator");
        System.out.println(add(5, 3));
        System.out.println(subtract(5, 3));
    }
}

When to use static?

Putting static before a method makes it callable without creating an object. The calculator methods are static because they're called directly from main.

Without static, you'd need to create an object first:

Main calc = new Main();
calc.add(5, 3);

That's an extra step, so keeping helper methods static is more practical.

Test yourself

Match the method types

static

Class-level
int

Returns integer
void

No return
return

Returns a value
What does add(2, 3) return?
- 1
- 23
- 6
- 5
Show answer

5 — add(2, 3) sums two numbers: 5.

Complete the return statement

static int add(int a, int b) { return a ____ b; }

Show answer

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

Next lesson: Multiply/divide

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