carfield.com.hk

Component.java

2004-03-24T16:00:00Z

CompositeA.java

2004-03-24T16:00:00Z

package examples.composite.java;

/* -*- Mode: Java; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * This file is part of the design patterns project at UBC
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.1 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * either http://www.mozilla.org/MPL/ or http://aspectj.org/MPL/.
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is ca.ubc.cs.spl.pattern.
 *
 * Contributor(s): 
 */
 
import java.util.LinkedList;				

/**
 * Implements a Composite. Children are stored in a linked list.
 *
 * @author Jan Hannemann
 * @author Gregor Kiczales
 * @version 1.0, 05/13/02
 * 
 * @see Component 
 * @see LeafB
 */

public class CompositeA implements Component {
 
 /**
 * stores the children for this component
 */
 
	protected LinkedList children = new LinkedList();		// Component interface

 /**
 * stores an ID for this composite
 */

	protected int id = 0;
	
 /**
 * Creates a new CompositeA with a given ID
 *
 * @param id the ID for the new object
 */

	public CompositeA(int id) {
		this.id = id;
	}
	 
 /**
 * Overwrites the <code>toString()</code> method from <code>Object</code>
 * to print information about this object
 */

	public String toString() {
		return ("I am A (ID "+id+")");
	}

	 
 /**
 * Adds a child to the component
 *
 * @param component the child to add
 */
 
	public void	add(Component component) {this.children.add(component);} 

 /**
 * Adds a child to the component
 *
 * @param component the child to add
 */
	public void remove(Component component) {this.children.remove(component);}

 /**
 * Returns a child of the component
 *
 * @param index the position of the child
 */
 
	public Component getChild(int index) {return (Component) children.get(index);}

 /**
 * Returns the number of chilren a component has
 *
 * @returns the number of children of this component
 */
 
	public int getChildCount() {return children.size();}
}

LeafB.java

2004-03-24T16:00:00Z

package examples.composite.java;

/* -*- Mode: Java; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * This file is part of the design patterns project at UBC
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.1 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * either http://www.mozilla.org/MPL/ or http://aspectj.org/MPL/.
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is ca.ubc.cs.spl.pattern.
 *
 * Contributor(s): 
 */
 
/**
 * Implements a Leaf. Leafs have no children.
 *
 * @author Jan Hannemann
 * @author Gregor Kiczales
 * @version 1.0, 05/13/02
 * 
 * @see Component 
 * @see CompositeA
 */

public class LeafB implements Component {

 /**
 * stores an ID for this composite
 */

	protected int id = 0;
	
 /**
 * Creates a new CompositeA with a given ID
 *
 * @param id the ID for the new object
 */

	public LeafB(int id) {
		this.id = id;
	}
	 
 /**
 * Overwrites the <code>toString()</code> method from <code>Object</code>
 * to print information about this object
 */

	public String toString() {
		return ("I am B (ID "+id+")");
	}
 
 
 /**
 * Adds a child to the component
 *
 * @param component the child to add
 */

	public void	 add(Component component) {}

 /**
 * Adds a child to the component
 *
 * @param component the child to add
 */

	public void	 remove(Component component) {}

 /**
 * Returns a child of the component
 *
 * @param index the position of the child
 */
 
	public Component getChild(int index) {return null;}

 /**
 * Returns the number of chilren a component has
 *
 * @returns the number of children of this component
 */
 
	public int	 getChildCount() {return 0;}
}

Main.java

2004-03-24T16:00:00Z

package examples.composite.java;

/* -*- Mode: Java; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * This file is part of the design patterns project at UBC
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.1 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * either http://www.mozilla.org/MPL/ or http://aspectj.org/MPL/.
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is ca.ubc.cs.spl.pattern.
 *
 * Contributor(s): 
 */
 
/**
 * Implements the driver for the composite design pattern example. 
 *
 * Intent: Compose objects into tree structures torepresent part-whole 
 * hierarchies. Composite lets clients treat individual objects and 
 * compositions of objects uniformly.
 *
 * Participatng classes are <code>CompositeA</code>s as Composites,
 * and a <code>LeafB</code> as Leaf. Both implement the 
 * Component interface.
 *
 * This example creates a simple structure as follows: Composite c1 has 
 * three children: l1, c2, and l3. c2 has l2 as a child.
 * Compact notation: c1(l1, c2(l2), l3)
 *
 * This is the Java version. 
 *
 * Every component and every leaf need to know about the pattern and their
 * in the pattern.
 *
 * @author Jan Hannemann
 * @author Gregor Kiczales
 * @version 1.0, 05/13/02
 * 
 * @see Component
 * @see CompositeA 
 * @see LeafB
 */
 
public class Main { 

	/**
	 * helper variable to store recursion depth for pretty printing
	 */
	 
	private static int indent = 0; 

 /**
 * Print a number of spaces according to the current recursion depth
 */
 	
	private static void indent() {
		for (int i=0; i<indent; i++)
			System.out.print(" ");
	}

 /** 
 * Pretty-prints a recursive composite structure 
 *
 * @param comp the component denoting the entry point into the structure
 */
 
	private static void printStructure(Component comp) { 
		indent();
		System.out.println("Showing: "+comp);
		indent +=4; 
		for (int i=0; i<comp.getChildCount(); i++) {
			printStructure(comp.getChild(i));
		}
		indent -= 4;
	}


 /**
 * This example creates a simple structure as follows: Composite c1 has 
 * three children: l1, c2, and l3. c2 has l2 as a child.
 * Compact notation: c1(l1, c2(l2), l3)
 */


	public static void main(String[] args) {
		CompositeA composite1 = new CompositeA(1);
		CompositeA composite2 = new CompositeA(2);
		LeafB 	 leaf1 = new LeafB(1);
		LeafB leaf2 = new LeafB(2);
		LeafB leaf3 = new LeafB(3); 
		
		composite1.add(leaf1);
		composite1.add(composite2);
		composite2.add(leaf2);
		composite1.add(leaf3); 
		
		printStructure(composite1);
	}
}

files.lst

2004-03-24T16:00:00Z