this and super keywords in Java

The two keywords, this and super to help you explicitly name the field or method that you want. Using this and super you have full control on whether to call a method or field present in the same class or to call from the immediate superclass. This keyword is used as a reference to the current object which is an instance of the current class. The keyword super also references the current object, but as an instance of the current class’s super class. The this reference to the current object is useful in situations where a local variable hides, or shadows, a field with the same name. If a method needs to pass the current object to another method, it can do so using the this reference. Note that the this reference cannot be used in a static context, as static code is not executed in the context...

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What is not possible using java class Inheritance?

1. Private members of the superclass are not inherited by the subclass and can only be indirectly accessed. 2. Members that have default accessibility in the superclass are also not inherited by subclasses in other packages, as these members are only accessible by their simple names in subclasses within the same package as the superclass. 3. Since constructors and initializer blocks are not members of a class, they are not inherited by a subclass. 4. A subclass can extend only one superclass class Vehicle {     // Instance fields     int noOfTyres; // no of tyres     private boolean accessories; // check if accessorees present or not     protected String brand; // Brand of the car // Static fields ...

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Inheritance in Java

In this Tutorial you’l learn about inheritance in Java. Java Inheritance defines an is-a relationship between a superclass and its subclasses. This means that an object of a subclass can be used wherever an object of the superclass can be used. Class Inheritance in java mechanism is used to build new classes from existing classes. The inheritance relationship is transitive: if class x extends class y, then a class z, which extends class x, will also inherit from class y. For example a car class can inherit some properties from a General vehicle class. Here we find that the base class is the vehicle class and the subclass is the more specific car class. A subclass must use the extends clause to derive from a super class which must be written in the header of the subclass definition. The...

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Interfaces vs Abstract Classes

1. Abstract class is a class which contain one or more abstract methods, which has to be implemented by sub classes. An abstract class can contain no abstract methods also i.e. abstract class may contain concrete methods. A Java Interface can contain only method declarations and public static final constants and doesn’t contain their implementation. The classes which implement the Interface must provide the method definition for all the methods present. 2. Abstract class definition begins with the keyword “abstract” keyword followed by Class definition. An Interface definition begins with the keyword “interface”. 3. Abstract classes are useful in a situation when some general methods should be implemented and specialization behavior should be implemented by subclasses. Interfaces...

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Polymorphism in Java

Polymorphism means one name, many forms. There are 3 distinct forms of Java Polymorphism; Method overloading (Compile time polymorphism) Method overriding through inheritance (Run time polymorphism) Method overriding through the Java interface (Run time polymorphism) Polymorphism allows a reference to denote objects of different types at different times during execution. A super type reference exhibits polymorphic behavior, since it can denote objects of its subtypes. interface Shape {     public double area();     public double volume(); } class Cube implements Shape {     int x = 10;     public double area() {         return (6 * x * x);     }    ...

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