Example of Composite Design Pattern

UML

Source Code

Composite.java


import java.applet.*;
import java.awt.*;

public class Composite extends Applet {
    Picture pict = new Picture();

    public void init() {
	pict.add(new Circle(new Point(10,10),50));
	pict.add(new Rectangle(10,80,60,140));
	pict.add(new Line(10,150,60, 170));
	pict.add(new Circle(new Point(100,80),20));
    }
    // This method is called whenever the applet needs to be drawn or redrawn

    public void paint(Graphics g) {
	pict.draw(g);

    }
}

shape.java

import java.awt.*;

public abstract class shape extends Object {
    Color fill, outline, textcolor;  // The various colors we use
    public shape() {
	// Initialize color resources.  Note the use of the Color() constructor
	// and the use of pre-defined color constants.
	fill = new Color(200, 200, 200); // Equal red, green, and blue == gray
	outline = Color.blue;            // Same as new Color(0, 0, 255)
	textcolor = Color.red;           // Same as new Color(255, 0, 0)
    }

    public void setFillColor(Color c) {
	fill = c;
    }

    public void setOutlineColor(Color c) {
	outline = c;
    }

    public void setTextColor(Color c) {
	textcolor = c;
    }

    public abstract void draw(Graphics g);
}

Picture.java


import java.awt.*;
import java.util.*;

public class Picture extends shape { // ISA relationship
    Vector list = new Vector(); // HASA relationship

    public void add(shape s) {
	list.addElement(s);
    }

    public void draw(Graphics g) {
	Iterator it = list.iterator();
	while (it.hasNext()){
	    it.next().draw(g);
	}
		
    }
}

Circle.java

import java.awt.*;

public class Circle extends shape {
	int radius;
	Point center;

	public Circle(Point c,int r) {
		center = c;
		radius = r;
	}

	public void draw(Graphics g) {
		g.setColor(fill);
		g.fillOval(center.x, center.y, radius, radius);
		g.setColor(outline);
		g.drawOval(center.x, center.y, radius, radius);
	}
};

Line.java

import java.awt.*;

public class Line extends shape {
    Point start,end;

    public Line(int sx,int sy,int ex,int ey) {
	start = new Point(sx,sy);
	end = new Point(ex,ey);
    }

    public void draw(Graphics g) {
	g.setColor(outline);
	g.drawLine(start.x,start.y,end.x,end.y);
    }
}

Rectangle.java

import java.awt.*;

public class Rectangle extends shape {
    Point ul,lr;

    public Rectangle(Point u,Point l) {
	ul = u;
	lr = l;
    }

    public Rectangle(int x1,int y1,int x2, int y2) {
	ul = new Point(x1,y1);
	lr = new Point(x2,y2);
    }

    public void draw(Graphics g) {
	g.setColor(fill);
	g.fillRect(ul.x, ul.y, lr.x - ul.x, lr.y - ul.y);
	g.setColor(outline);
	g.drawRect(ul.x, ul.y, lr.x - ul.x, lr.y - ul.y);
    }
}

Point.java

public class Point {
     public int x;
     public int y;
     public Point() {
	x = y = 0;
     }
     public Point(Point p) {
	x = p.x;
	y = p.y;
     }
     public Point(int i,int j) {
	x = i;
	y = j;
     }
}

build.xml

<?xml version="1.0" ?>
<project default="main">

	<target name="main" depends="compile, compress">
		<echo>
			Building the .jar file
		</echo>
	</target>

	<target name="compile">
		<javac srcdir="."/>
	</target>

	<target name="compress">
		<jar jarfile="c2.jar" basedir="." includes="*.class" />
	</target>

</project>