Java UML Class

[Alex Arcay]

Hi everyone,

Firstly I must say what an excellent forum this is, I'm very happy I found it. I have been tasked to create a UML class diagram and an object diagram, unfortunately I have no idea how to put it together.

The application I have been coding is a simple calculator with four different functions (add, subtract, multiply and divide).

Here is my code, any help would be appreciated!

package Calc;
//Imports the scanner that I will be using.
import java.util.Scanner;
/**
 *
 * @author alex
 */
public class Calc {
     //Public static void for the class.
    public static void main(String[] args) {
        //Welcome print at the start of application.
        System.out.println("Welcome to the Calculator V1.O");
        //Blank line seperator.
        System.out.println("");
        System.out.println("What would you like to do today?");
        System.out.println("");
        //The options that will be shown to the program user in the console.
        //Option List for the program.
      System.out.println("1. Add");
      System.out.println("2. Subtract");
      System.out.println("3. Divide");
      System.out.println("4. Multiply");
      //Scans for the selected option.
      //Creates a new scanner.
      Scanner scan = new Scanner(System.in);
      //Checks if the next integer is selected.
      //Variables set to load the functions of each calculator.
      //Scans the integer choices.
      int choice = scan.nextInt();
        switch (choice) {
            case 1:
                addition();
                break;
            case 2:
                subtraction();
                break;
            case 3:
                division();
                break;
            case 4:
                multiply();
                break;
            default:
                //Print this line if 1-4 are not selected.
                System.out.println("Option Unavailable");
                break;
        }
    }
    
 public static void addition(){ 
     //Input a new scanner.
     Scanner input = new Scanner( System.in ); 
     //Collects the data from number1 and number2.
     int number1; 
     int number2; 
     int sum; 
     //Menu name
     System.out.println( "Addition" );
     //Creates the message for the first number.
     System.out.print( "Enter your first number: " ); 
     //Creates the message for the second nmber.
     number1 = input.nextInt(); //Defines number1 
     System.out.print( "Enter your second number: " ); 
     number2 = input.nextInt(); //Defines number2 
     //Use addition symbol between the two numbers.
     sum = number1 + number2; 
     System.out.printf( "Sum equals %d\n", sum); 
}
 
 public static void subtraction(){ 
   Scanner input = new Scanner( System.in ); 
     int number1; 
     int number2; 
     int sum; 
 System.out.println( "Subtraction" );
     System.out.print( "Enter your first number: " ); 
     number1 = input.nextInt(); //Defines number1 
     System.out.print( "Enter your second number: " ); 
     number2 = input.nextInt(); //Defines number2 

     sum = number1 - number2; 
     System.out.printf( "Sum equals %d\n", sum);  
} 

public static void division(){ 
   Scanner input = new Scanner( System.in ); 
     int number1; 
     int number2; 
     int sum; 

     System.out.println( "Division" );
     System.out.print( "Enter your first number: " ); 
     number1 = input.nextInt(); //Defines number1 
     System.out.print( "Enter your second number: " ); 
     number2 = input.nextInt(); //Defines number2 

     sum = number1 / number2; 
     System.out.printf( "Sum equals %d\n", sum);  
} 

public static void multiply (){ 
    //Multiplication
    //New scanner.
    Scanner input = new Scanner( System.in ); 
    //Int number from below.
     int number1; 
     int number2; 
     //The sum answer displayed.
     int sum; 

      System.out.println( "Multiply" );
     System.out.print( "Enter your first number: " ); 
     number1 = input.nextInt(); //Defines number1 
     System.out.print( "Enter your second number: " ); 
     number2 = input.nextInt(); //Defines number2 

     sum = number1 * number2; 
     System.out.printf( "Sum equals %d\n", sum);  
    }
    
}

[Jeanne Boyarsky]

Alex,
Welcome to CodeRanch!

The second diagram on this page shows a class diagram.


Since you only have one class and no instance variables, your class diagram will be very simple. It'll be a box with an empty top section and the methods in the bottom section.

An object diagram doesn't apply because you don't have any states - only static methods. Maybe your teacher wants you to have instance variables?

[Alex Arcay]

Thank you for your helpful message. I would like to just ask if you think I can complete this task simply? I am trying to get signed off my course as soon as possible (before university in September) and this is the last thing holding me back unfortunately! I have already made the calculator, I just need to make the diagrams.

My task information for this part:

3a) Design an OOP application using UML Class and Object diagrams that represents a Library management system. The scope of the application is up to you in terms of how simple or complex it is, but it must be realistic in its considerations of different objects and attributes. – P3

3b) Implement a working object oriented application based on the Library management system designed above. The application must accurately replicate the class and object diagrams designed above.

[Jeanne Boyarsky]

The assignment talks about a library, not a calculator. Also, I don't think your calculator program is designed in a way that will let you complete the assignment.

In order to complete this task, it looks like you are going to have to learn about instance variables and how to create a program with multiple classes. Luckily, September is a few months away so you have plenty of time.