Java This Keyword

Defining What is This Keyword in Java

Essential Features of This Keyword in Java

• It can be used to refer to the current class instance variable.
• It can be used to invoke the current class method.
• It can be used to invoke the current class constructor.
• And it can also be passed as an argument in the method call.

Efficient Ways to Use This Keyword in Java

class Student {
int age;

  void setAge(int age) {
    age = age;
  }
}

class Student {
int age;

  void setAge(int age) {
    this.age = age;
  }
}

Practical Example of This Keyword in Java

class Person {
  String name;
  int age;
  double weight;

  Person(String name, int age, double weight) {
    this.name = name;
    this.age = age;
    this.weight = weight;
  }
}

In Java, This Keyword is Used To: Key Functions and Roles

• 'this' can be used to call an overloaded constructor in the same class.
• 'this' can be used to pass itself to another method or constructor.
• 'this' can be used to return the current class instance from the method.

Examining the Java This Keyword Usage in More Detail

class Vehicle {
  int maxSpeed;

  Vehicle(int maxSpeed) {
    this.maxSpeed = maxSpeed;
  }

  void display() {
    System.out.println("Max speed: " + this.maxSpeed);
  }
}

Exploring the Java Super Keyword

As you delve deeper into the expansive world of Java, another keyword that you'll often encounter alongside 'this' is 'super'. The 'super' keyword also holds a significant place in Java syntax and programming, and understanding its usage and benefits is essential. It is a reference variable that helps to refer to the immediate parent class object. Each time you create an instance of a class, the 'super' keyword is created as a symbol of the parent class.

Understanding This and Super Keyword in Java

Both 'this' and 'super' keywords have their own unique functionalities, and both serve different purposes, though they are often confused because of their somewhat related usages.

• 'Super' can be used to refer to immediate parent class variable.
• 'Super' can be used to invoke immediate parent class method.
• 'Super()' is used to invoke immediate parent class constructor.

Recognising the Importance of Super Keyword in Java

Comprehensive Example of Java Super Keyword

class Animal {

  void eat() {
    System.out.println("Animal is eating...");
  }

}

class Dog extends Animal {

  void eat() {
    super.eat();
    System.out.println("Dog is eating...");
  }

}

Super Keyword: Applying it within Java Code

class Parent {
  int x = 10;
  
  void display() {
    System.out.println("Parent's x: " + x);
  }
}

class Child extends Parent {
  int x = 20;
  
  void display() {
    super.display();
    System.out.println("Child's x: " + x);
  }
}

Distinguishing Between This and Super Keyword in Java

Fundamental Difference between This and Super Keyword in Java

How to Identify This and Super Keyword in Java

class Employee {
  int id;

  void setId(int id) {
    this.id = id;
  }
}

class Shape {
  void area() {
    //calculate area
  }
}

class Rectangle extends Shape{
  void area() {
    super.area();
    //calculate rectangle area
  }
}

When to Use This Keyword and Super Keyword in Java Programming

class Vehicle {
  int speed;

  Vehicle(int speed) {
    this.speed = speed;
  }
}

class Car extends Vehicle {
  String engine;

  Car(int speed, String engine) {
    super(speed);
    this.engine = engine;
  }
}