OOP Concepts in Java

Composition in Java with code examples

Composition "Have a " Relationship OR "Must have" relationship between two or more classes. Container class contains component's class object For example a Car is composed of engine and body. Where Car is a container class and both Engine and Body are components class. Life Time Issue in Composition Life time of component objects depends on container class If Container object destroyed, component objects will be also destroyed Car Example There is a composition relationship between car's body and engine. Car must have Engine and body If Car destroyed, both Engine and Body will be destroyed class Engine { Engine () { System.out.println ( "Engine created" ) ; } void start () { System.out.println ( "Engine Start" ) ; } } class Body...

Aggregation in java with example codes

What is aggregation? "Have a" or "May have" relationship Aggregation is special type of association Life time of Component object is independent from its container object E.g A school has one student class Student { String name; Student () { name= null ; } Student ( String n ) { name=n; } void setName ( String n ) { name=n; } String getName () { return name; } } class School { Student st; School ( ) { st= null ; } School ( Student s ){ st=s; } void studentName (){ System.out.println ( st.getName ()) ; } } class Post { public static void main ( String a []){ Student st= new Student ( "Imran" ) ; School s= new School ( st ) ; s.studentName () ; } } Output Hello ...

Generalization in java with examples

Generalization basic points Type/Subtype Relationship "IS A " Relationship One class has many subclasses General class can have many Special classes as subclasses General names can be used to Address special names Top to bottom hierarchy goes towards specialization Bottom to top Hierarchy goes towards generalization e.g Soap Bath Soap and Washing Soap is a subclass of Soap e.g COldDrink Pepsi Team -Cold Drink is a general class -Pepsi and team are special classes e.g Person Teacher Student e.g Car Sedan Hatchback Honda Suzuki Suzuki Toyota civic Liana Alto vitz ..........................................

Java Tutorials and codes

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