Thread: Simple OOP question- Creating objects

I am very new to programming in Java. Can anyone take this code and add comments ( // ) so I can better understand what each line does?

 
class TestNumber                                            // creates Class  named TestNumber
{
   public static void main(String[] args)                // This is the main method
   {
      Number n1 = new Number(10);                   // To my understanding, this will create an object n1  and assign 10 to that object?
      Number n2 = new Number(20);
      Number n3 = n1.add(n2);                            
      System.out.println("n3 = " + n3.toString());
   }
}
//================================================
class Number
{
   private int x;
   //----------------------------------
   public Number(int xx)
   {
      x = xx;
   }
   //----------------------------------
   public Number add(Number r)
   {
      return new Number(x + r.x);
   }
   //----------------------------------
   public String toString()
   {
      return "" + x;      // return value in x as String
   }
}

Originally Posted by TSSF44

I am very new to programming in Java. Can anyone take this code and add comments ( // ) so I can better understand what each line does?

 
class TestNumber                                            // creates Class  named TestNumber
{
   public static void main(String[] args)                // This is the main method
   {
      Number n1 = new Number(10);                   // To my understanding, this will create an object n1  and assign 10 to that object? (yes, type of the object is Number)
      Number n2 = new Number(20);                   // Samething
      Number n3 = n1.add(n2);                          // This will create object and assign return value from add method.  
      System.out.println("n3 = " + n3.toString());  // this line will print n3 to console
   }
}
//================================================
class Number // Class definition
{
   private int x; // Class variable called x
   //----------------------------------
   public Number(int xx) // Constructor
   {
      x = xx; // While creating number objects, you need to send integer values as you do above, so this line will assign passed number to class variable x, so you can use x in other methods.
   }
   //----------------------------------
   public Number add(Number r) // Defining method add
   {
      return new Number(x + r.x); // Creates a new Number 
   }
   //----------------------------------
   public String toString() // This is class method overriding, you describe how toString method of Number class will display the number here.
   {
      return "" + x;      // return value in x as String
   }
}

Here you go