title: Simple Calculator - If statement
body: <p>I am new to java and programming.<br>
  Can someone suggest what can be used so that the answer must equal to <code>+,-,*,/ ?</code> At the moment I am trying to create an if statement but I am getting an error and I am not quite sure why. Can someone look at my code and help me complete the if statement please? If you have any other suggestions on what can be improved, please share.</p>
  
  <pre><code>import java.util.Scanner;
  
  public class Calculator {
  public static void main (String Args []) {
      Scanner input = new Scanner(System.in);
      double firstNumber, secondNumber;
      String equationOperator;
  
      System.out.println("Please give your first number: \t");
      firstNumber = input.nextDouble();
      System.out.println("Please give your second number: \t");
      secondNumber = input.nextDouble();
      System.out.println("Which equation would you like to perform?");
      System.out.println("Please enter one of the following + - / * \t");
      equationOperator = input.next();
  
      switch (equationOperator) {
      case "+":
          System.out.println("Your chosen equation is: Adding");
          System.out.println("Your answer is: " + (firstNumber + secondNumber));
          break;
      case "-":
          System.out.println("Your chosen equation is: Subtracting");
          System.out.println("Your answer is: " + (firstNumber - secondNumber));
          break;
      case "/":
          System.out.println("Your chosen equation is: Dividing");
          System.out.println("Your answer is: " + (firstNumber / secondNumber));
          break;
      case "*":
          System.out.println("You chosen equation is: Multiplying");
          System.out.println("Your answer is: " + (firstNumber * secondNumber));
          break;                  
      }
      if (!equationOperator.equals("+ || - || / || *") {
          System.out.println("Please choose one of the following:");
          System.out.println("+"
                  + "-"
                  + "/"
                  + "*");
                  }
      System.out.println("\t Thank You for using my Calculator");
  
          }
  
  
   }
  </code></pre>