What is the difference between an interface and an abstract class?

Vaibhav Kothia May 26, 2023 0 Comments

An interface is a collection of abstract methods and constants that form a common set of base rules for a class to follow. An interface does not contain any implementation code, and it cannot be instantiated. An example of an interface might be a Comparable interface which defines the compareTo() method.

An abstract class is a class that contains both abstract methods (methods without an implementation) and concrete methods (methods with an implementation). An abstract class can be instantiated, and it is often used as a base class from which other classes can inherit. An example of an abstract class might be an Animal class which defines the abstract method makeSound() and the concrete method eat().

How do you define a class in Java?

Vaibhav Kothia May 26, 2023 0 Comments

A class in Java is a template that is used to create objects, and to define the properties and behaviors of those objects.

For example, a Car class could be used to create objects that represent individual cars. The Car class would specify the properties of a car, like its make, model, and color, as well as the behaviors, like accelerate, brake, and turn.

public class Car {

// Properties of the class…
private String make;
private String model;
private int year;
private String color;

// Constructor of the class…
public Car(String make, String model, int year, String color) {
this.make = make;
this.model = model;
this.year = year;
this.color = color;
}

// Methods of the class…
public void accelerate() {
System.out.println(“Vroom!”);
}

public void brake() {
System.out.println(“Screech!”);
}

public void turn(String direction) {
System.out.println(“Turning ” + direction + “.”);
}

}

What is the difference between a class method and an instance method?

Vaibhav Kothia May 26, 2023 0 Comments

A class method is a method that is defined in a class and can be called directly from the class without having to create an instance of the class first. An example of a class method is the __init__() method in Python.

An instance method is a method that is defined in a class and can only be called on an instance of the class. An example of an instance method is the __str__() method in Python.

What is the difference between an instance variable and a property?

Vaibhav Kothia May 26, 2023 0 Comments

An instance variable is a variable that is declared inside a class and is accessible from any method within that class. An example of an instance variable would be:

class Person {
private String name;

public Person(String name) {
this.name = name;
}

public String getName() {
return name;
}
}

A property is a special type of variable that is used to access a class’s member variables from outside the class. An example of a property would be:

class Person {
private String name;

public Person(String name) {
this.name = name;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}
}

What is the difference between a class and an object?

Vaibhav Kothia May 26, 2023 0 Comments

Class: A class is a blueprint for creating objects. It is a template that describes the properties and behaviors of a type of object.

For example, a class called “Car” could describe the properties of a car, such as its color, make, model, and year. It could also describe the behaviors of a car, such as accelerating, braking, and turning.

Object: An object is an instance of a class. It is a concrete example of the class, with its own set of data and behaviors.

For example, a car object could be a specific car, such as a red Honda Accord from 2019. This object would have its own color, make, model, and year, and it would be able to accelerate, brake, and turn.