Java Inheritance concepts
Composition vs Inheritance After Encapsulation, the second OOPS feature is "Inheritance". In the previous Parrot program, the Parrot created an object of Bird and used Bird's method eat(). Now in inheritance, we call the eat() method with Parrot object itself (and not with Bird object). This is the difference between composition and inheritance. In composition, …
Types of Inheritance There exists basically three types of inheritance. Multilevel inheritance Multiple inheritance Hierarchical inheritance 1. In single inheritance, one class extends one class only. In multilevel inheritance, the ladder of single inheritance increases. 2. In multiple inheritance, one class directly extends more than one class. 3. In hierarchical inheritance one class is extended …
Extends Java An OOPs language is meant more for reusability. It achieves reusability with "has-a" relation (through composition) and "is-a" relation (through inheritance). For "has-a" relationship, known as composition in Java, refer Composition – "has-a" Relationship. Now let us discuss inheritance and how the reusability is achieved. To get the concept, very small programs are …
In the earlier, Bird-Ostrich inheritance program, Ostrich extends only one class, Bird, because Ostrich wants to walk and the method is there in Bird’s class. Now Ostrich also wants to eat but the eat() method is there in another class Animal. Now, it is required to Ostrich to extend two classes Bird and Animal. Observe …
Subclass can make use of super class methods straight away by virtue of inheritnace. If the subclass does not satisfy about the functionality (output) of the super class method, the subclass can rewrite with its own functionality with the same method name. This concept is known as "method overriding", supported by OOP languages like C++/Java. …
Basically, both this vs super Java are keywords performing different jobs. this keyword refers an object super keyword refers a super class variable or method A) Meaning, Purpose and Usage of this Keyword this refers an object, that too, a current object. What is current object? To understand better, let us write a small program …
Java Made Clear: Difference between this and super Example Read More »
We know earlier, in method overriding, the subclass method supersedes the super class method. When the method is overridden in inheritance, the subclass object calls its own method. If it calls its own method, the subclass looses the functionality of the super class method (of course, subclass is at liberty). If the subclass would like …
final Keyword Java After going through "static" and "super" keywords, let us go another keyword "final". These three keywords, known as access modifiers, are used very often in Java code. The final keyword behaves very differently when applied to variables, methods and classes. Even though its functionality (purpose) is different in the three contexts, but …
super vs final Java are keywords of Java but doing very different jobs. super keyword is used to access super class variables and methods by subclass object when they are overridden by subclass. final is used in three places in Java with different jobs. final variable cannot be reassigned (like const of C/C++) final method …
static vs final java, both are known access modifiers in Java doing different functionalities (used for different jobs). static: static keyword can be applied to instance variables and methods but not to classes. When applied, variables and methods can be called without the help of an object. When a method or variable is called without …
Java Made Clear: Difference between static and final Keywords Read More »
this Keyword Java "this" keyword refers an object, to say, the current object. Observe the following program and pay attention to this.salary. public class Officer3 { int salary; public void display(int salary) { this.salary = salary; } public static void main(String args[]) { Officer3 o1 = new Officer3(); o1.display(5000); System.out.println(o1.salary); // 5000 } } In …
