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Consider a modified version of the class Circle:

import java.lang.Math;

public class Circle
{
    // Accessor methods
    public double x()      { return m_x; }
    public double y()      { return m_y; }
    public double radius() { return m_r; }

    // Mutator methods
    public void x(double v)      { m_x = v; }
    public void y(double v)      { m_y = v; }
    public void radius(double r) { m_r = r; }

    // Operations/Attributes
    public double getCircumference()
                { return 2 * Math.PI * m_r; }
    public double getArea()
                { return Math.PI * m_r*m_r; }

    // Data
    double m_x, m_y; // coordinates of center
    double m_r; // radius
}

where I've changed the accessor and mutator method names for illustrative purposes.

Note: The Java standard naming convention is to use getFoo and setFoo as names for the accessor and mutator methods for an attribute named foo.  I strongly recommend that you follow this convention in all your Java code.  (Note that the Sun Java programmers did not initially follow this convention in early Java classes, but they do in all current code.)

Method Overloading

This version of the Circle class contains several examples of method overloading:

Each overloaded method shares a name (in our case, x, y, or radius)

Method Signature

Each method is distinguished by its signature:

• its name, and
• the number, types and positions of its arguments
• but not its return type!

So, if you enter the two functions into the Circle class:

public double getArea()
{ return Math.PI * m_r*m_r; }

public int getArea()
{ return Math.PI * m_r*m_r; }

You will get a compilation error:

Methods 'double Circle.area()' and 'int Circle.area()'
differ only in return type

This page was last modified on 02 October, 2007