Basic Calculator program in Java

Calculator.java

package com.osfg;

import java.util.Scanner;

/**
 * 
 * @author aniket
 * 
 * Basic Calculator program in Java
 */
public class Calculator {

	Scanner scanner;
	
	//boolean to terminate calculator program base on user input
	private boolean calculatorStarted;

	public Calculator() {
		scanner = new Scanner(System.in);
		calculatorStarted = true;
	}

	public void startCalculator() {
		
		boolean invalidInputs = false;

		while (calculatorStarted) {
			invalidInputs = false;
			System.out.println("Enter 1 for addition \n" + "Enter 2 for subtraction \n"
					+ "Enter 3 for multiplication \n" + "Enter 4 for division \n" + "Enter 0 for Exit : ");

			int operator = scanner.nextInt();
			
			float firstNo = 0;
			float secondNo = 0;
			
			if(operator != 0) {
				System.out.println("Enter first number : ");
		        firstNo = scanner.nextFloat();
		        System.out.println("Enter second number : ");
		        secondNo = scanner.nextFloat();
			}
			
	        
	        float result = 0;
			
			switch (operator) {
			case 1:
				result = add(firstNo, secondNo);
				break;

			case 2:
				result = subtract(firstNo, secondNo);
				break;

			case 3:
				result = multiply(firstNo, secondNo);
				break;

			case 4:
				if(secondNo == 0) {
					System.out.println("Please provide proper input \n");
					invalidInputs = true;
					break;
				}
				result = divide(firstNo, secondNo);
				break;

			case 0:
				calculatorStarted = false;
				System.out.println("Calculator program Terminated \n");
				break;

			default:
				invalidInputs = true;
				System.out.println("Please provide proper input \n");

			}
			
			/**
			 * Show the result only if inputs are valid
			 * and user had not chose to terminate calculator
			 */
			if(!invalidInputs && operator != 0) {
				System.out.println("Result is " + result);
			}		

		}

	}
	
	
    private float add(float number1, float number2) {
        return number1 + number2;
    }
 
    private float subtract(float number1, float number2) {
        return number1 - number2;
    }
 
    private float multiply(float number1, float number2) {
        return number1 * number2;
    }
 
    private float divide(float number1, float number2) {
        return number1 / number2;
    }
	
	

}