------Abstract class of Java

Enclosing image abstract class and its subclasses

Area.java:

Public interface area{public   double Area ();}

Circle.java:

Public final class Circle extends Ellipse        //Circle class, End class {public    circle (double radius)                 //constructor method, radius parameter specifies radius of circle    {        super (Radius,radius);        This.shape = "Round";    }    Public Circle ()    {This        (0);    }    Public String toString ()    {        return "radius" +this.radius_a;    }    public static void Main (string[] args)     {        new Circle (). print ();    }}

Closedfigure.java:

Public abstract class Closedfigure//Closed graph abstract Classes {protected String shape;    Shape protected closedfigure (String shape)//constructor method, cannot be abstract method {this.shape = shape;    } protected Closedfigure () {This ("unknown");               } public abstract double area (); Calculate area, abstract method, with semicolon ";"          Ends public abstract double perimeter (); Calculate perimeter, abstract method public void print ()//Display shape, property, perimeter, and area {System.out.println ("one" +this.shape    + "," +this.tostring () + ", Circumference is" +this.perimeter () + ", area is" +this.area () ");  }}class closedfigure_ex {public static void main (String args[])//abstract class can contain the main () method {Closedfigure g =     New Ellipse (10,20);                               G Reference Ellipse object G.print ();                      Show Ellipse Properties g = new Circle (10);        Round G.print ();                g = new Rectangle (10,20);                               G Reference Rectangle object G.print ();Display Rectangle Property g = new Square (10);    Square g.print (); }}

Ellipse.java:

public class Ellipse extends closedfigure              //Ellipse class {    protected double radius_a;                   A-axis radius    protected double radius_b;                   B-Axis radius public    Ellipse (double radius_a, double radius_b)//construction method    {        super ("Ellipse");        This.radius_a = radius_a;        This.radius_b = Radius_b;    }    Public Ellipse ()    {This        (0,0);    }        Public String toString ()    {        return "A-axis radius" +this.radius_a+ ", B-Axis radius" +this.radius_b;    }        Public double area ()                         //computes the ellipse size, overriding the parent class's abstract method    {        return math.pi*this.radius_a*this.radius_b;    }    Public double perimeter ()                    //computes the perimeter of the ellipse, overriding the abstract method of the parent class    {        return math.pi* (this.radius_a+this.radius_b);    }    public static void Main (String args[])    {        new Ellipse (10,20). print ();    }}

Rectangle.java:

public class Rectangle extends Closedfigure//Rectangle class {protected double length;                      length protected double width;        Width public Rectangle (double length, double width)//constructor method {Super ("rectangle");        this.length = length;    This.width = width;    } public Rectangle () {this (0,0);    } public Rectangle (Rectangle R) {This (r.length, r.width);    The public String toString () {return "Length" +this.length+ ", width" +this.width;    } public double area ()//calculates the rectangle size, implementing the parent class's abstract method {return this.width*this.length;    } public double perimeter ()//calculates the perimeter of the rectangle, implementing the abstract method of the parent class {return (this.width+this.length) * *;    } public void SetLength (double length) {this.length = length;    } public void SetWidth (double width) {this.width = width;    } public double GetLength () {return this.length; } public DoubLe getwidth () {return this.width;    } public static void Main (String args[]) {new Rectangle (10,20). print (); }}

Square.java:

Public final class Square extends Rectangle      //Square is a special case of rectangle {public    square (double width)    {        Super (width, width);        This.shape = "Square";    }    Public Square ()    {This        (0);    }        Public String toString ()    {        return "edge length" +this.length;    }    public static void Main (string[] args) {        new Square (). print ();}}

------Abstract class of Java