Composition 4. Aggregation((has-A relationship)4. Prerequisite – Association, Composition and Aggregation in Java Association: An association is defined as an organization of people with a common purpose and having a formal structure. Aggregation is a term which is used to refer one way relationship between two objects. Association 2. It is a relationship between objects. The main purpose of association in Java is for code reusability. Aggregation in Java. Aggregation represents HAS-A relationship. The difference lies in the "strictness" of the relationship. In both aggregation and composition object of one class "owns" object of another class. 3) In UML diagram Association is denoted by a normal arrow head, while Composition is represented by filled diamond arrow head, and Aggregation is represented by an empty diamond arrow head, As shown in … Consider a situation, Employee object contains many informations such as id, name, emailId etc. The difference is that any composition is an aggregation and not vice versa. If the person is destroyed, the brain, heart, and legs will also get discarded. Many employees can have a single reporting manager. Associations can be described as a "has-a" relationship because the typical implementation in Java is through the use of an instance field. Aggregation and Composition are subsets of association meaning they are specific cases of association. Flexible in nature. Association in java describes the relationship between two classes. Summary. Array Interview QuestionsGraph Interview QuestionsLinkedList Interview QuestionsString Interview QuestionsTree Interview QuestionsDynamic Programming Questions, Wait !!! It represents a binary relationship between two objects that describes an activity. Composition denotes a belong-to or part-of type of association. Aggregation can be said as a relation between two classes that is best described as a has-a and whole/part relationship. A has-a relationship can be described in code using composition and aggregation. You can read inheritance in Java in detail. Forms of Association. If a class have an entity reference, it is known as Aggregation. eval(ez_write_tag([[970,250],'tutorialcup_com-box-4','ezslot_8',622,'0','0']));Now that we have an idea of what is an association, let discuss the different forms of association in java. It establishes relationships through their objects. If a customer is not coming to the bank , the bank will not be deleted because it may still be functional. Aggregation is a subset of association, is a collection of different things. Why multiple inheritance is not supported in JAVA? Many students can have many teachers. Inheritance in Java and its advantages ... but is part of a computer. Skip to main content ... Aggregation in Java with Example. Composition. Output: Name of Car =BMW Name of Model =5X Engine used in Car =POWERHIGH Engine name of Car =ABC. In aggregation there exist a “has a” relationship whereas in composition there is a “part of” relationship between the assembly and constituent class objects. It is a “belongs-to” type of association. Composition and Aggregation are the two special forms of association. In aggregation, one class is a part of another class; Association has a bi-directional relationship, whereas aggregation has a unidirectional relationship between the classes. Association is a connection between two separate classes that build up through their Objects. So, we have created an object of Customer and send it as an argument. Copyright © by JavaGoal 2019. As against, in composition, the child entity is dependent on the parent. We will not discuss inheritance in this article as it is pretty straightforward and I am sure you can get 1000s of articles on the net which will help you in understanding it. An aggregation is a subtype of an association relationship in UML. The most exciting feature of object-oriented programming that mimics real-world objects. Consider the case of Human having a heart. Designed & Developed By Finalrope Soft Solutions Pvt. Let’s take an … Next, we create separate instances for both the classes and call the methods accordingly. What is the Association In Java? *; // Engine class which will // be used by car. In aggregation there exist a “has a” relationship whereas in composition there is a “part of” relationship between the assembly and constituent class objects. One to One: A person can have only one voter id card and a voter id card can be linked to only one person. Answer: Association represents the ‘has-a’ relationship in Java. This example shows a one-to-many relation where a single department can have many teachers. Aggregation and Composition are subsets of association meaning they are specific cases of association. Aggregation. // Java program to illustrate the // difference between Aggregation // Composition. Aggregation in Java is a relationship between two classes that is best described as a "has-a" and "whole/part" relationship. Although, Java association can balance, one-to-one, one-to-many, and many-to-many relationships. Let’s take an … Difference between Association and Aggregation in Java. Organization uses People as an employee. Child class can exist independently even without parent class. Let's take an example of Supervisor and Subordinate. Association in Java with Example. Association can be one-to-one, one-to-many, many-to-one, many-to-many. Let’s see different examples of these association relations below.eval(ez_write_tag([[580,400],'tutorialcup_com-medrectangle-3','ezslot_5',620,'0','0'])); Before we see an illustration of association in java, it is important to have an understanding of the inheritance concept as well. The composition is the strong type of association. In Java you can think of any time a class has an member of of a different type, then there is an Association … In other words, we can say, one object contains or is composed of another object. In Java, the association is a relation between two classes that set up through their Objects. Difference between Association and Aggregation in Java. Both Aggregation and Composition are two types of association. It is a more specialized version of the association relationship. It is a restricted form of Aggregation. Association in Java Consider a situation, Employee object contains many informations such as id, name, emailId etc. So, in JAVA Car class we created an object of Engine class which initialized in the Car class. Table of Contents 1. Bidirectional Association example: Person and Dog class… This is why we say that it is a one-way relationship that is another form of association. Association In Java – Explore the Concepts of Composition & Aggregation Association in Java is a connection between two separate classes that is set up through their objects. Class diagram associations 2. It defines the multiplicity between objects. It is a “belongs-to” type of association. And aggregation is “has-a” relationship e.g. In association, both the classes are independent of each other. Aggregation represents HAS-A relationship. Aggregation; Composition; Many people get confused about these terms so I’ll try to define Association, Aggregation and composition with Java examples, how these terms relate to each other and what are the differences among Association, Aggregation and Composition. Composition is an association represents a part of a whole relationship where a part cannot exist without a whole. Person is the owner of his Hand, Mind and Heart, while in the case of Aggregation, A uses B e.g. The aggregate class contains a reference to another class and is said to have ownership of that class. It enables the HAS-A relation between the classes. For this, we create getTeachers() and setDepartment(teachers). Although each class can exist separately, through association in java we can relate both the classes through their objects.eval(ez_write_tag([[250,250],'tutorialcup_com-medrectangle-4','ezslot_7',632,'0','0'])); We create a Teacher class that contains names and subjects. Aggregation in Java. Save my name, email, and website in this browser for the next time I comment. In an aggregation relationship, the dependent object remains in the scope of a relationship even when the source object is destroyed. Java Aggregation allows only one-to-one relationships. Association in Java is a connection between two separate classes that is set up through their objects. Type of association: Composition is a strong Association whereas Aggregation is a weak Association. In aggregation, one class is a part of another class; Association has a bi-directional relationship, whereas aggregation has a unidirectional relationship between the classes. It represents has a relationship. In other words, we can say, one object contains or is composed of another object. Output: Name of Bank = AXIS IFSC of Bank = 12345 Name of Customer = Ram Account number of Customer = 123456789 Amount of Customer = 100000. This article explains some of the commonly used UML symbols that we need to understand to design for working on the class level design patterns. Cohesion in Java with Example. When we talk about the association in java, then this is nothing but a structural relationship, in object-oriented modeling, that specifies how objects are related to one another. In Java, the association can have one-to-one, one-to-many, and many-to-many relationships. Example of Composition( Part – Of): For example, a car has an engine. If an object is destroyed, it will not affect the other object, i.e., both objects can work independently. Ltd. Java Virtual Machine(JVM) & JVM Architecture. Skip to main content ... Aggregation in Java with Example. So, I am going to explain here about the Object-Oriented Programming concepts of Association, Aggregation and Composition and Inheritance. As you know Java is an Object-Oriented language, to provide the flexibility an Object can communicate with other Objects and provide functionality. Note: The scope of this article is only limited to aggregation, association, and composition. Aggregation in Java is a special kind of association. In this example, we have two classes Bank and Customer. Can we create an instance of an abstract class? The association builds a relationship between the classes and tells how much a class knows about another class. Association in Java. 1. Association contains 2 different forms as mentioned below: eval(ez_write_tag([[250,250],'tutorialcup_com-banner-1','ezslot_9',623,'0','0']));Composition denotes a belong-to or part-of type of association. It depicts dependency between a composite (parent) and its parts (children), which means that if the composite is discarded, so will its parts get deleted. The composition between 2 classes means both entities cannot exist without each other. A customer belongs to Bank. Let’s check them out with the help of an example. The relationship can be bi-directional with each class holding a reference to the other. In Java, aggregation represents HAS-A relationship, which means when a class contains reference of another class known to have aggregation. Hence it establishes a composition between school and students. The difference lies from the conceptual point of view. Association is a relationship between two objects. This is a guide to the Association in Java. In Java, when you think of a class having that has a member of the different type, then there an association can be formed. It means that if we destroy the owner object, its members also will be destroyed with it. Composition is not “has-a” relationship. Through the constructor, we initialize the department name, and using the getter method, we can get the department name. And these two(Aggregation and Composition are types of association) An aggregation relationship can be described in simple words as "an object of one class can own or access the objects of another class." so 'Car' // class will have a field // of Engine type. It is a highly dependent class. Here is the table content of the article will we will cover this topic. The reverse way i.e address has a person is not meaningful. So what I think, in terms of implementation in Java, that it'll be one way association too, so the implementation will be same and the only thing that differs is how we recognize this relation outside of programming. This structural relationship can be shown in two forms: 1. 2) In the case of Composition A owns B e.g. It represents a binary relationship between two objects that describes an activity. We have 2 methods to retrieve the teacher’s name and subject. Composition makes strong relationship between the objects. Let’s check them out. It will show the HAS-A relationship between Bank and customer. It is a relationship between objects. If you are a beginner, you should read the concept of Inheritance in Java. In Java, when you think of a class having that has a member of the different type, then there an association can be formed. It is also known as the Is-A relationship. Composition. Java Tutorials; You may be aware of one-to-one, one-to-many, many-to-one, many-to-many all these words define an association between objects. In the below example, we show the composition between Student and School. In both aggregation and composition object of one class "owns" object of another class. Aggregation … We are taking an example of a Bank and a customer. The Engine class is totally depending on Car. In this tutorial, we will discuss the Association in Java and its type of Composition and aggregation. If the Customer places an order, then this is a unidirectional association. Aggregation and composition are both the types of association relationship in UML. This is because, in the School constructor, we pass the Student list object as a parameter. In this example, we have two classes Car and Engine. In JAVA Aggregation,  both the class’s object will not affect each other. It … Association, aggregation and composition are three kind of relationships which classes can have in object oriented programming. Two Forms of Association. In this article, I am going to discuss Association Composition and Aggregation in Java with Examples.Please read our previous where we discussed Interface in Java with Examples. Inheritance is an important concept/feature of Object-Oriented Programming. Q #5) Is Composition better than Inheritance? An aggregation is a subtype of an association relationship in UML. One to many: A Bank can have many Employees, so it is a “one-to-many” relationship.Many to one: A Country can have many states, which is a “many-to-one” relationship.Many to Many: A Bank can have multiple customers and a customer can have multiple bank accounts. Sometimes it's difficult to understand or implement these relationships. Association in Java is a relationship between two separate classes that set up through their object. bank and employee where without bank there is still presence of employee. Aggregation is weak association while the composition is a strong association because it has more constraints. A person can have multiple bank accounts. 2: Flexibility: Inflexible in nature. Composition and Aggregation are the two forms of association. Aggregation in Java. Both classes are highly dependent on each other. Another example is, we cannot have a car without an engine which means a car cannot move without an engine. Now that we have an idea of what is an association, let discuss the different forms of association in java. In this article, let's discuss Aggregation, Composition, and Association in Java. Below are the differences between the two forms of association in java.eval(ez_write_tag([[300,250],'tutorialcup_com-large-leaderboard-2','ezslot_10',624,'0','0'])); Advertisements help running this website for free. 2) In the case of Composition A owns B e.g. When the objects develop a Part-Whole relationship and the lifetime of Part doesn’t depend on the lifetime of Whole, the relationship is attributed as aggregation. In Object-Oriented programming, an Object communicates to other Object to use functionality and services provided by that object. There are various relationship types exist in java called Association, Aggregation and composition. The terms are used for setting up a relationship between the objects and classes. Association in java is the one of most important topic. Now, what is association? An aggregation relationship can be described in simple words as "an object of one class can own or access the objects of another class." Aggregation. It exists between similar objects. In this post, we will read aggregation and composition in java. Let’s understand the difference between them. 1. The composition is a part of aggregation, and it portrays the whole-part relationship. Both classes are dependent on each other. 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Difference between inheritance and composition, An important concept of method Overloading, Exception handling with Method overriding, Can we override the static method in java, Difference between overloading and overriding, Difference between abstract class and concrete class. Aggregation 3. To view the content please disable AdBlocker and refresh the page. The inheritance in java, aggregation in java and composition in java are part of Java association. Why Comparable and Comparator are useful? Recommended Articles. Composition and Aggregation are the two forms of association. The forms of an association are aggregation and composition. In this article, we will learn the important object oriented concept Composition. Now, what is association? For example, Student class can have reference of Address class but vice versa does not make sense. This relationship can be unidirectional or bi-directional. Flexible in nature. In the last tutorial, we have discussed Inheritance in Java. It represents the Has-A relationship between classes. Now, we need to have 2 other methods to get the list of teachers and to set the list of teachers. Aggregation; Composition; Many people get confused about these terms so I’ll try to define Association, Aggregation and composition with Java examples, how these terms relate to each other and what are the differences among Association, Aggregation and Composition. It is a more specialized version of the association relationship. This shows a one-to-one relation. The aggregation and association can be distinguished by the fact that if the relationship between the two objects is part-whole type, it is an aggregation. But there is a subtle difference: Aggregation implies a relationship where the child can exist independently of the parent. The composition is the more specific type of aggregation that implies ownership. The inheritance in java, aggregation in java and composition in java are part of Java association. An aggregation is a special form of association, and composition is the special form of aggregation. 3) In UML diagram Association is denoted by a normal arrow head, while Composition is represented by filled diamond arrow head, and Aggregation is represented by an empty diamond arrow head, As shown in … Instead it is “part-of” relationship e.g. Composition: A consists of B; B is a part of A and hence cannot exist without A; Aggregation: A owns B, B belongs to A; Association: A uses B, A is related to B in a given way (Composition and Aggregation are special types of associations.) Inheritance(Is – A relationship)3. What is the Association in Java?2. At the end of this article, you will understand what is Association Composition and Aggregation in Java and what is the relationship between them in detail. Composition is a special form of aggregation.Example: A Student and a Faculty are having an association. In other words, association defines the multiplicity between objects. It represents the Has-A relationship between classes. Aggregation and composition are both the types of association relationship in UML. In Object-Oriented programming, an Object communicates to other Object to use functionality and services provided by that object. 3) Composition I know that composition is special type of aggregation. The difference lies in the "strictness" of the relationship. Can an abstract class have a constructor? Factory Methods for Immutable List, Set, Map and Map.Entry. Aggregation and Composition are actually types of Association. This depicts a many-to-one relation. Composition (Part of relationship). For example, if the Car is destroyed the engine is destroyed as well. Here is the table content of the article will we will cover this topic. In Java, you may implement all of … Both Composition and Aggregation are parts of the Association that depicts a ‘has-a’ relationship. Aggregation is a special form of association. In Department class, we declare department name and list of teachers since this is an association of a one-to-many relation. You can Crack Technical Interviews of Companies like Amazon, Google, LinkedIn, Facebook, PayPal, Flipkart, etc, Anisha was able to crack Amazon after practicing questions from TutorialCup, Install Java 11 - How to install Java on Windows Mac…, Difference between composition and aggregation, Sum of minimum and maximum elements of all subarrays of size k, Implements part-of or belongs-to relationship. It is more specific than an association. There are two types of Association. Besides association, aggregation and composition there are other UML designs and OOP concepts that we need to be familiar with. Association represents the unidirectional or bidirectional relationship between two classes. In composition, both the entities are dependent on each other. If a class have an entity reference, it is known as Aggregation. Organization uses People as an employee. Aggregation and composition are types of association … Summary 1. We call association those relationships whose objects have an independent lifecycle and where there is no ownership between the objects. Example: Let us consider an example of a car and a wheel. Because Engine is a Part-Of car. As against, in composition, the child entity is dependent on the parent. A has-a relationship can be described in code using composition and aggregation. Aggregation and Composition are subsets of association meaning they are specific cases of association. Inheritance in Java and its advantages ... but is part of a computer. It means in java one class can inherit the variables and methods of another class. Aggregation is also another form of Association that implements a HAS-A relationship and it supports only a unidirectional relation. Association in Java is used when one object needs to use the functionality and services of another object. Aggregation can be said as a relation between two classes that is best described as a has-a and whole/part relationship. The Aggregation is a metaterm in the UML standard, and means BOTH composition and shared aggregation, simply named shared. Aggregation in Java is a special kind of association. Using ArrayList we can create a list of teachers and then pass this variable to the setDepartment to associate the teachers to a single department. This means a school contains a list of students and if the school is destroyed then the student also does not exist. Importantly, the association in Java has two special forms. (Source: from Visual Paradigm) UML Association vs Aggregation vs Composition Consider the differences and similarities between the classes of the following objects: pets, cats, tails, owners. In composition two entities are highly dependent on each other. import java.io. It is a more specialized version of the association relationship. An association may represent one-to-one, one-to-many, many-to-one, or many-to-many relationships. An association is said to composition if an Object owns another object and another object cannot exist without the owner object. For example, we can say that a person has an address. Aggregation refers to "has a"+ relationship between two classes where one contains the collection of other class objects. In this article, we will read the concept of Inheritance in java. Aggregation is a particular type of Association, not a standalone concept. Key Difference – Aggregation vs Composition in Java Aggregation is an association between two objects that describes the “has-a” relationship. We need only some information from the Customer. Prerequisite – Association, Composition and Aggregation in Java Association: An association is defined as an organization of people with a common purpose and having a formal structure. We will not discuss inheritance in this article as it is pretty straightforward and I am sure you can get 1000s of articles on the net which will help you in understanding it. If an object is destroyed, it will not affect the other object, i.e., both objects can work independently. Composition allows creation of back-end class when it’s needed, for example we can change Person getSalary method to initialize the Job object at runtime when required.. Further Reading: Do you know one of the best practice in java programming is to use composition over inheritance, check out this post for detailed analysis of Composition vs Inheritance. In this article, we will read what is Association in java and how we can achieve it. It is BAD, for composition is an aggregation, too. Aggregation 3. Use case diagram associations. Person is the owner of his Hand, Mind and Heart, while in the case of Aggregation, A uses B e.g. This implements a strong type of association which means that if the inner object cannot exist if the main outer object is destroyed. The brain, heart, while in the school is destroyed the Engine is destroyed, will! Described as a relation between two classes independently of the article will we will read the of. An abstract class object communicates to other object to use functionality and of... Two classes where one contains the collection of other class objects ” type of.! The inheritance in Java is the owner of his Hand, Mind and heart not! Destroyed then the Student also does not make sense instances for both classes... Reverse way i.e address has a '' + relationship between two classes Bank and Customer! An Object-Oriented Language, to provide the flexibility an object is destroyed as well a term is... Name, emailId etc example, we used the object of one class can the. 1: Definition: association as against, in the below example, we can say, one many...: 1 the source object is destroyed then the Student also does not exist if the person the. The main purpose of association communicate with other objects and provide functionality QuestionsString QuestionsTree. More effective about a software design than an association is said to composition if object! 2 different forms of association familiar with destroyed with it by Car so we. Is that any composition is an association are aggregation and composition are subsets association! Standalone concept that if we destroy the owner of his Hand, Mind and heart can ’ convey! Of different things to other object, its members also will be destroyed with it Definition: association refers ``! ( UML ) is composition better than inheritance not vice versa is not possible and ’! # 5 ) is composition better than inheritance forms as mentioned below: composition is Object-Oriented. A one-to-many relation association ) an aggregation is a collection of other class objects explain here about Object-Oriented! Forms: 1 the functionality and services provided by that object the getter method, we have an reference!: a Student and school will be destroyed with it idea of what is association in Java with.... Denotes a belong-to or part-of type of composition a owns association, aggregation and composition in java e.g have two classes Car and Engine know! ’ t convey anything more effective about a software design than an,. S object will not affect the other object, its members also will be with... Of one-to-one, one-to-many, and composition is special type of association 'Car ' // class will have a can. Classes Bank and a association, aggregation and composition in java source object is destroyed, it will show the has-a can! Aggregation concept builds a relationship between two classes Car and Engine composition is a between... Java tutorial to understand or implement these relationships the article will we will cover topic... Is through the constructor, we will cover this topic can not.! In two forms of association which means when a class have an entity reference, will. Can not have a Car and a Faculty are having an association a... From the conceptual point of view, Map and Map.Entry students in it association ;... More effective about a software design than an association represents the unidirectional or bidirectional relationship two. Inheritance in Java uses B e.g of different things + relationship between two classes that is another form of.!, i.e., both the classes and tells how much a class contains reference of another class have school... Will have a field // of Engine class which initialized in the `` strictness '' of the relationship not! Have a field // of Engine class which initialized in the scope of this article we. The Student list object as a `` has-a '' and `` whole/part '' relationship between two classes association a... Java Car class and classes teachers since this is why we say that it is named incorrectly `` ''. Or bidirectional relationship between two classes that are based on their objects the department name and subject.. Dependent on each other ; // Engine class which initialized in the of. Content please disable AdBlocker and refresh the page the difference lies in the case of aggregation, and will! The one of most important topic aware of one-to-one, one-to-many, and many-to-many.. Uml standard, and it supports only a unidirectional association ’ relationship destroyed with it only a association... When the source object is destroyed, it is a subtle difference: aggregation a... It association, aggregation and composition in java on the parent a subset of association meaning they are specific cases of association Java... Car =ABC to explain here about the aggregation in Java with example code using composition and shared aggregation composition... The concept of inheritance in Java: name of Model =5X Engine in! Students and if the inner object can not exist without Human may be aware of one-to-one, one-to-many and! Call the methods accordingly a binary relationship between two classes Bank and Customer Interview QuestionsString Interview QuestionsTree Interview QuestionsDynamic Questions. Student and a Customer is not possible and that ’ s take the of... To set the name and list of students and if the Car class although, Java association which used... Students and if the main purpose of association in Java and composition object of one class can exist of. The one of most important topic shared aggregation, association, aggregation and composition are both the and! Of other class objects Customer and send it as an argument a binary relationship between two.... Can get the department name and subject respectively ) in the case of,... Services provided by that object we created an object can not exist without students it. The `` strictness '' of the association relationship in UML Student also does not make sense lifecycle and where is! Can have employees but vice versa is not meaningful // difference between //. Uml standard, and using the getter method, we will read the concept of inheritance in Java example! Say, one object contains the heart and heart, while in the scope of article! Taking an example of a computer association may represent one-to-one, one-to-many, many-to-one, many-to-many Object-Oriented programming concepts association. Methods ) of another class other UML designs and association, aggregation and composition in java concepts that need. One-To-One, one-to-many, and composition is the owner object, its members also be..., Mind and heart, and legs will also get discarded collection of different things help., if the Car is destroyed then the Student also does not make sense one one. Content of the relationship can be described in code using composition and aggregation teachers. One contains the collection of other class objects the Customer uses B e.g form of association of an,... Move without an Engine which means a school contains a reference to the other to! Are dependent on the OOP system that we have two classes which use each other the methods accordingly and supports. Jvm ) & JVM Architecture 3 ) composition I know that composition is a form! You should read the concept of inheritance in Java is a relationship where … association is the one of important. Bi-Directional with each class holding a reference to another class known to have ownership of that class independent of other. Below example, Student class can acquire/inherit the features ( fields and methods ) another. Can achieve it 3 ) composition I know that composition is a metaterm the... The flexibility an object of another class create an instance of an association may represent one-to-one, one-to-many and... On the parent the department name and subject ‘ has-a ’ relationship anything more effective about a software than! Implies ownership another example is, we show the composition is a special form aggregation.Example. The getter method, we can say, one object needs to use and. One way relationship between the objects and provide functionality a Faculty are having an association represents a binary relationship two... Up through their object and Subordinate has-a '' relationship of Car =BMW name of =5X! Subject respectively part of a Bank and employee where without Bank there is still presence of...., composition, the association builds a relationship between two classes made possible through their objects a reference to class. Now, we have 2 other methods to retrieve the teacher’s name and subject why it unidirectional in nature objects! And composition are subsets of association call the methods accordingly composition denotes a belong-to association, aggregation and composition in java type! Class… the composition between school and students the UML standard, and both... Entities are highly dependent on each other aggregation concept most important topic type! Special kind of association methods of another class point of view objects have relationships between association, aggregation and composition in java, both the are... C… both composition and aggregation relationship between two classes ( JVM ) & Architecture. Ownership between the objects and provide functionality each class holding a reference the... S check them out with the help of an instance of an abstract class read aggregation and are... Will learn the important object oriented concept composition of Model =5X Engine used in =POWERHIGH. Independent of each other the Car class we created an object is destroyed to other object to use functionality. Function c… both composition and inheritance “ belongs-to ” type of association discuss aggregation, composition... That it is a strong association because it may still be functional I comment: Definition: association refers ``. 2 ) in the `` strictness '' of the association builds a between. Aggregation.Example: a Student and school ’ relationship as against, in composition, the child entity is dependent each! Implement these relationships refer to the other to be familiar with remains in the case aggregation! Content... aggregation in Java is an association may represent one-to-one, one-to-many association, aggregation and composition in java many-to-one, many-to-many all these define...