Composition is the design technique to implement has-a relationship in classes. We can use java inheritance or Object composition for code reuse. Java composition is achieved by using instance variables that refers to other objects. Job.java package com.journaldev.composition; public class Job { private String role; private long salary; private int id; public String getRole() { return role; } public void setRole(String role) { this.role = role; } public long getSalary() { return salary; } public void setSalary(long salary) { this.salary = salary; } public int getId() { return id; } public void setId(int id) { this.id = id; } } Person.java package com.journaldev.composition; public class Person { //composition has-a relationship private Job job; public Person(){ this.job=new Job(); job.setSalary(1000L); } public long getSalary() { return job.getSalary(); } } | 0 |
By: [email protected] On: Thu Mar 13 16:14:01 IST 2014 0 359 0 | 359 |
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Composition is a Has-A relationship...means one class can use the functionality of another class using the object of that class...see below class A { int x=10;} class B { int y=20; A a=new A(); System.out.println(a.x+" "+y); } its a sample example to understand composition... | 0 |
By: [email protected] On: Mon Mar 17 00:43:25 IST 2014 5 19 0 | 24 |
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difference between composition and aggregation? | 0 |
By: [email protected] On: Wed Oct 14 12:19:04 IST 2015 0 0 0 | 0 |
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Composition is a special case of aggregation. In a more specific manner, a restricted aggregation is called composition. When an object contains the other object, if the contained object cannot exist without the existence of container object, then it is called composition. Example: A class contains students. A student cannot exist without a class. There exists composition between class and students. Composition is more restrictive. When there is a composition between two objects, the composed object cannot exist without the other object. This restriction is not there in aggregation. Though one object can contain the other object, there is no condition that the composed object must exist. The existence of the composed object is entirely optional. In both aggregation and composition, direction is must. The direction specifies, which object contains the other object. Example: A Library contains students and books. Relationship between library and student is aggregation. Relationship between library and book is composition. A student can exist without a library and therefore it is aggregation. A book cannot exist without a library and therefore its a composition. For easy understanding I am picking this example. Don?t go deeper into example and justify relationships! | 0 |
By: [email protected] On: Wed Jan 27 17:49:14 IST 2016 0 0 0 | 0 |
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