Java/Language Basics/Object Oriented Design — различия между версиями
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Текущая версия на 09:47, 1 июня 2010
Class Hierachy
<source lang="java">
/*
* Copyright (c) Ian F. Darwin, http://www.darwinsys.ru/, 1996-2002. * All rights reserved. Software written by Ian F. Darwin and others. * $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $ * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS"" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. * * Java, the Duke mascot, and all variants of Sun"s Java "steaming coffee * cup" logo are trademarks of Sun Microsystems. Sun"s, and James Gosling"s, * pioneering role in inventing and promulgating (and standardizing) the Java * language and environment is gratefully acknowledged. * * The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for * inventing predecessor languages C and C++ is also gratefully acknowledged. */
import java.util.*; /** Part of a main program using Shape objects */ public class ClassShapeMain {
Collection allShapes; // created in a Constructor, not shown /** Iterate over all the Shapes, getting their areas */ public double totalAreas() { Iterator it = allShapes.iterator(); double total = 0.0; while (it.hasNext()) { Shape s = (Shape)it.next(); total += s.ruputeArea(); } return total; }
} class Circle extends Shape {
double radius; public double computeArea() { return Math.PI * radius * radius; }
} class Rectangle extends Shape {
double width, height; public double computeArea() { return width * height; }
} abstract class Shape {
protected int x, y; public abstract double computeArea();
}
</source>
Hierarchy 2
<source lang="java">
/*
* Copyright (c) Ian F. Darwin, http://www.darwinsys.ru/, 1996-2002. * All rights reserved. Software written by Ian F. Darwin and others. * $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $ * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS"" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. * * Java, the Duke mascot, and all variants of Sun"s Java "steaming coffee * cup" logo are trademarks of Sun Microsystems. Sun"s, and James Gosling"s, * pioneering role in inventing and promulgating (and standardizing) the Java * language and environment is gratefully acknowledged. * * The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for * inventing predecessor languages C and C++ is also gratefully acknowledged. */
public class Customer extends Person {
private int customerNumber; public Customer(String firstName, String lastName, int number) { super(firstName, lastName); setCustomerNumber(number); } public void setCustomerNumber(int n) { if (n < 1) throw new IllegalArgumentException("Invalid customer number " + n); customerNumber = n; }
} class Person {
String firstName; String lastName; Person(String firstName, String lastName) { this.firstName = firstName; this.lastName = lastName; }
} class Employee extends Person {
private short deptCode; private int staffNumber; public Employee(String firstName, String lastName, short dept, int number) { super(firstName, lastName); setDeptCode(dept); setStaffID(number); } public void setDeptCode(short dept) { deptCode = dept; } public void setStaffID(int number) { if (number < 1) throw new IllegalArgumentException("Invalid staff number " + number); staffNumber = number; }
}
</source>
This class shows how we might control the objects
<source lang="java">
/*
* Copyright (c) Ian F. Darwin, http://www.darwinsys.ru/, 1996-2002. * All rights reserved. Software written by Ian F. Darwin and others. * $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $ * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS"" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. * * Java, the Duke mascot, and all variants of Sun"s Java "steaming coffee * cup" logo are trademarks of Sun Microsystems. Sun"s, and James Gosling"s, * pioneering role in inventing and promulgating (and standardizing) the Java * language and environment is gratefully acknowledged. * * The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for * inventing predecessor languages C and C++ is also gratefully acknowledged. */
/**
* BuildingManagement - control an energy-saving building. * This class shows how we might control the objects in an office * that can safely be powered off at nighttime to save energy - lots of * it, when applied to a large office! */
public class BuildingManagement {
Asset things[] = new Asset[24]; int numItems = 0; /** goodNight is called from a timer Thread at 2200, or when we * get the "shutdown" command from the security guard. */ public void goodNight() { for (int i=0; i<things.length; i++) if (things[i] instanceof PowerSwitchable) ((PowerSwitchable)things[i]).powerDown(); } // goodMorning() would be the same, but call each one"s powerUp(). /** Add a Asset to this building */ public void add(Asset thing) { System.out.println("Adding " + thing); things[numItems++] = thing; } /** The main program */ public static void main(String[] av) { BuildingManagement b1 = new BuildingManagement(); b1.add(new RoomLights(101)); // control lights in room 101 b1.add(new EmergencyLight(101)); // and emerg. lights. // add the computer on desk#4 in room 101 b1.add(new ComputerCPU(10104)); // and its monitor b1.add(new ComputerMonitor(10104)); // time passes, and the sun sets... b1.goodNight(); }
} abstract class BuildingLight extends BuildingAsset {
// generic info on lighting: flourescent/incandescent, ... BuildingLight(int roomNumber) { super(roomNumber); }
} abstract class ComputerAsset extends Asset {
// generic computer component stuff here: location, owner, // warranty expiration date :-), etc. int deskNumber; ComputerAsset(int deskNumber) { this.deskNumber = deskNumber; }
} class ComputerCPU extends ComputerAsset {
// information about CPU (P5, P6, ...), RAM, etc. ComputerCPU(int deskNumber) { super(deskNumber); }
} /** Asset is the top level of every Asset */ abstract class Asset extends Object {
// No fields or methods; it"s just the base of everything.
} class EmergencyLight extends BuildingLight { // NEVER SWITCH OFF
EmergencyLight(int roomNumber) { super(roomNumber); }
} /**
* PowerSwitchable is an Interface that will be implemented by things * that can safely be turned off at night. Could use X10(tm) or BlueTooth * or 802.11 or any similar network technology to turn things on or off. * * @author Ian F. Darwin */
interface PowerSwitchable {
/** The technique for turning this unit off */ public void powerDown(); /** The technique for turning this unit on */ public void powerUp();
} class RoomLights extends BuildingLight implements PowerSwitchable {
RoomLights(int roomNumber) { super(roomNumber); } public void powerDown() { System.out.println("Dousing lights in room " + room); } public void powerUp() { System.out.println("Lighting lights in room " + room); }
} /** The top level of everything that is permanently part of the building */ abstract class BuildingAsset extends Asset {
protected int room; public BuildingAsset(int room) { this.room = room; }
} class ComputerMonitor extends ComputerAsset implements PowerSwitchable {
ComputerMonitor(int roomNumber) { super(roomNumber); } public void powerDown() { System.out.println("Dousing monitor at desk " + deskNumber); // send the code to the Monitor"s X10 box to shut it off } public void powerUp() { System.out.println("Warming up monitor at desk " + deskNumber); // send the code to the Monitor"s X10 box to turn it on }
}
</source>