Calculator.java

import java.io.*;

public class Calculator {

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

		BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
		System.out.println("Enter First number");
		double num1 = Double.parseDouble(reader.readLine());
		System.out.println("Enter second nuber");
		double num2 = Double.parseDouble(reader.readLine());
		System.out.println(
				"Enter + for Addition \n" + "- for Subraction\n" + "* for Multiplication\n" + "/ for Division");
		String input = reader.readLine();
		char operation = input.charAt(0);
		Condition(num1, num2, operation);
	}

	private static void Condition(double num1, double num2, char operation) {

		switch (operation) {

			case '+':
				System.out.println("The sum of " + num1 + " and " + num2 + " is " + DoAddition(num1, num2));
				break;

			case '-':
				System.out.println("The sum of " + num1 + " and " + num2 + " is " + DoSubract(num1, num2));
				break;

			case '*':
				System.out.println("The sum of " + num1 + " and " + num2 + " is " + DoMultiply(num1, num2));
				break;

			case '/':
				System.out.println("The sum of " + num1 + " and " + num2 + " is " + DoDivision(num1, num2));
				break;
		}

	}

	static double DoDivision(double a, double b) {
		return a / b;
	}

	static double DoMultiply(double a, double b) {
		return a * b;
	}

	static double DoAddition(double a, double b) {
		return a + b;
	}

	static double DoSubract(double a, double b) {
		return a - b;
	}
}