[Small talk design mode] relationship between classes

4. Composition)

Definition:Compared with aggregation, combination is a more coupling Association. A class with a composite relationship represents the association between "Whole-part", and "whole" is responsible for the life cycle of "part". They are co-occurrence and co-occurrence; and the "part" exists independently. If it is a composite relationship, if the whole is damaged, the individual will be damaged, while the aggregated individual may be shared by multiple entities, it may not be damaged as a whole.

Symbol: Solid diamond solid line arrow

1. The compositing relationship is a kind of association relationship, which is stronger than the aggregation relationship.
2. It requires that the object representing the whole in a common aggregation relationship be responsible for representing the lifecycle of some objects.

Code:

Package COM. ex. composition;/***** Project name: UML * Class Name: CPU * class description: A computer computing device * Creator: yinxiangbing * Creation Time: 04:23:33 * @ version 6.0 **/public class CPU {private string code; private string name; Public CPU (string code, string name) {This. code = Code; this. name = Name ;}} package COM. ex. composition;/***** Project name: UML * Class Name: Computer * class description: a development tool computer * created by: yinxiangbing * Creation Time: 01:34:49 * @ version 6.0 **/public class computer {private string code; private string name; private CPU; // The member variables in the composite relationship are usually assigned the Public Computer (string code, string name, CPU) {This. code = Code; this. CPU = CPU ;}}

5. Generalization)

Definition: Inheritance indicates the parent-child relationship between a class and a class (or between an interface and an interface. In Java, the extends keyword indicates the inheritance relationship. Inheritance (special individual is kind of general individual.

Symbol: Solid line representation with hollow arrows

Arrows point to normal individuals

Code:

Package COM. ex. generalization;/***** Project name: UML * Class Name: Animal * class description: Animal * Creator: yinxiangbing * Creation Time: 10:20:32 * @ version 6.0 **/public class animal {public void eat () {}public void sleep () {}} package COM. ex. generalization;/***** Project name: UML * Class Name: Bird * class description: Bird * Creator: yinxiangbing * Creation Time: 10:20:49 * @ version 6.0 **/public class bird extends animal {public void fly (){}}

6. Implementation)

Definition:Indicates the method that a class implements one or more interfaces. The interface defines the set of operations, and the Implementation class completes the specific operations of the interface. Use implements in Java.

Symbol:Represented by dotted lines + hollow arrows

Arrow pointing to interface

Code:

Package COM. ex. implementation;/***** Project name: UML * Class Name: USB * class description: USB interface * Creator: yinxiangbing * Creation Time: 10:23:01 * @ version 6.0 **/public interface USB {// access the computer public void connect (); // disconnect the computer public void disconnect ();} package COM. ex. implementation;/***** Project name: UML * Class Name: Camera * class description: Camera * Creator: yinxiangbing * Creation Time: 10:44:10 * @ version 6.0 **/public class camera implements USB {public void connect () {system. out. println ("normal camera access to computer");} public void disconnect () {system. out. println ("camera disconnected") ;}} package COM. ex. implementation;/***** Project name: UML * Class Name: MP3 * class description: MP3 * Creator: yinxiangbing * Creation Time: 10:44:38 * @ version 6.0 **/public class MP3 implements USB {public void connect () {system. out. println ("MP3 normal computer access");} public void disconnect () {system. out. println ("MP3 disconnected") ;}} package COM. ex. implementation;/***** Project name: UML * Class Name: Computer * class description: Computer * Creator: yinxiangbing * Creation Time: 10:22:03 * @ version 6.0 **/public class computer {public void useusb (USB) {USB. connect (); USB. disconnect ();} public static void main (string [] ARGs) {computer CPU = new computer (); // camera cam = new camera (); CPU. useusb (CAM); // camera MP3 MP3 = new MP3 (); CPU. useusb (mp3 );}}