Notes from Week 5 CSE 115 Spring 2006 February 13, 15 & 17, 2006

Writing Methods is a two-step process Give definition of how method will perform – write the method. When we want the work of the method to actually get done – the method call.

Writing the method (defining the method) Specify Method Signature: Visibility Return type Name for method Parameter list Specify Method Body: Code that method must execute to perform required task.

Method Writing - Method Signature Visibility public is best if you want anyone to be able to call your methods. Return type void if nothing is returned. If something is returned, need to use keyword return in method body to indicate value being returned.

Method Writing - Method Signature Give the method a name (mind the rules) Method is an identifier Style: first letter lower case, each subsequent word capitalized. Eg) myFirstMethod

Method Writing - Method Signature Parameters (formal parameters) Specify for each Type Name Why do parameters get a name in the method definition? So we can refer to them inside the method body.

Method Writing - Method Body Code that is executed when method is called. Need additional variables inside the method? Create a local variable. Local variables are only accessible from inside the method body.

Method Calling Method call: instanceName.methodName(); Pass in actual values for each of the required parameters. (actual parameters) Do something with the return type if there is one. (What if you don’t?)

”Strings are surrounded by quotes” List of Characters Characters are any single letter, digit, or symbol In code: ”Strings are surrounded by quotes”

Printing information to the console (screen) System.out.println(”Some text.”);

Inheritance Can be viewed as a specialization of a superclass. Can be viewed as generalizing several subclasses into a superclass.

Generalization Relationship “is a” relationship There is a superclass and a subclass In code: public class ClassB extends ClassA { }

Inheritance Basics When a subclass extends a superclass, the subclass inherits all public capabilities (methods) of the superclass and they remain public in the subclass. When a class has a superclass and we create an instance of the subclass, the no-argument constructor of the superclass is called automatically from the constructor of the subclass.

Accessors & Mutators Methods inside of a class that work with the instance variables to provide the value of the instance variable and to change the value of the instance variable respectfully.

Method Overloading Two methods can have the same name only if they differ in number and/or type of parameters. Constructors can be overloaded too!

Accessors (get methods) Access the value of an instance variable. public TypeOfProperty getProperty(){ return _instanceVariableName; }

Mutators (set methods) Change the value of an instance variable. public void setProperty (TypeOfProperty newValue) { _instanceVariableName = newValue; }