Reading Class Documentation

The Structure of a Method Declaration

A method declaration gives:

• the method's name
• the types of its parameters and their order (and descriptive placeholder names)
• the return type of value the method returns (or void if the method doesn't return a value)
• The example below shows the first two method declarations in the class documentation for the Aquarium class.

  

A method declaration is also called the method's signature.

Reading and Calling Methods

Do-Something Methods

• There is a special return type, void for methods that do something but do not return a value.
• The simplest methods have no parameters and no return value.

  From the AquaFish Documentation:

  
  ...
  
  

  Changing Direction:

  fish1.changeDir();
fish1.moveForward();

• The method declaration might specify one or more parameters, giving the type and a descriptive name for each parameter. When calling the method, provide parameters of the correct type. (Names do not matter.)

  From the Clock Documentation:

  

  Setting the time:

  myClock.setHour(10);      // Must pass an int parameter
  myClock.setMinute(45);    // Must pass an int parameter

Return-Something Methods

• Methods may return a value, in which case it is important to know what type of value it will be. These methods might or might not need parameters.
• Calls to methods that return a value should be embedded in larger statements or the return value should be captured in a variable. Otherwise, the return value is lost.

  From the Clock Documentation:

  

  Printing the time after capturing return values in variables:

  String hr = myClock.getHH();      // Returns a String
  int min = myClock.getMinute();    // Returns an int
  System.out.println(hr + ":" + min);
           // Might print 09:3 instead of 09:03; Why?

  Embedding the method calls in a larger statement:

  System.out.println(myClock.getHH() + ":" +
      myClock.getMinute);
           // Might print 09:3 instead of 09:03; Why?