Using static/class methods, this, and overloading

Static or class methods are available to all objects created from a class. In that sense, they are global

They are referenced as classname.method rather than objectname.method

Static/class methods -

	can be invoked without instantiating an object
	can access class member variables
	cannot access instance member variables
	cannot use this

Example --

public class Gizmo
{
    private static final String manufacturer = "Gizmo Inc.";
    ...
    public static String getManufacturer()
    {
        return manufacturer;
    }
    ...
    // to use this ->
    MessageBox.show("Made by "+Gizmo.getManufacturer());
    ...
}

	Overloading - Having 2 or more methods with the same name; they differ by the type and number of parameters -- Unique parameter lists are the key public class TV { public void setAspectRatio(int width, int height) { ... } public void setAspectRatio(double ratio) { ... } public void setAspectRatio() { ... } }
	Use -- private TV tv; ... tv.setAspectRatio(100,75); // or tv.setAspectRatio(7.0/3.0);

	*this* is a reference that always refers to the current object; same as in C++, but with "." instead of "->"
	It is used primarily to eliminate ambiguity
	It is also used to eliminate passing the current object as a parameter when another object of the same type is passed to a method
	Example -- public class Gizmo // a class definition { private int length; // member variables of the class private int width; private int depth; public Gizmo(int length, int width, int depth) //a constructor { this.length = length; // initialize the member variables this.width = width; // with values from passed this.height = height; // parameters of the same name } } Download aspectRatio source code - pay particular attention to the code behind the Movie, Square, and TV buttons Last updated by DrB on Wednesday, February 18, 2009