Java Tutorials

• Invoking a Method
• The this Reference

Methods

• Methods in Java define the behavior of the class.
• Methods are similar to procedures or subroutines in other languages.
• The real benefits of object orientation come from hiding the implementation of a class behind its operations.
• Methods access the internal implementation details of a class that are hidden from other objects.
• Hiding data behind methods is so fundamental to object orientation it has a name - encapsulation.
• Methods have zero or more parameters.
• A method can have a return value.
• A method's statements appear in a block of curly braces { and } that follow the method's signature.

      public void speak ()
      {
          System.out.println("Hey Barney ...");
      }
  

Invoking a Method

• Provide an object reference and the method name, separated by a dot (.):

      fred.speak();
  

• Parameters are passed to methods as a comma-separated list.
• A method can return a single value as a result, such as an int:

      public int add (int a, int b)
      {
          return a+b;
      }
  

• A method can return no result:

      public void setFirstName (String firstName)
      {
          this.firstName = firstName;
      }
  

The this Reference

• Occasionally the receiving object needs to know its own reference.

      public void move (double x, double y)
      {
          this.x = x;
          this.y = y;
      }