Java Programming Fundamentals

What are the four main data types in Java?

• int, char, double, boolean

• array, set, map, tuple

• float, string, long, short

• byte, decimal, object, list

Explain the difference between 'if' and 'switch' control structures in Java.

• 'if' is used for looping, while 'switch' is for single conditions.

• 'if' is faster than 'switch' for large datasets, making it more efficient.

• The 'if' structure is for conditional checks, while 'switch' is for selecting among multiple cases based on a variable's value.

• 'if' can only evaluate boolean expressions, whereas 'switch' can evaluate any data type.

What is encapsulation in Object-Oriented Programming?

• Encapsulation is the bundling of data and methods that operate on that data, restricting direct access to some of the object's components.

• Encapsulation is the method of exposing all data members of a class to the outside world.

• Encapsulation is the process of creating multiple instances of a class.

• Encapsulation refers to the inheritance of properties from a parent class.

What is the purpose of an interface in Java?

• To define a contract for classes to implement, allowing for abstraction and multiple inheritance.

• To allow classes to inherit from multiple classes directly.

• To provide a way to create objects without defining methods.

• To serve as a blueprint for creating new data types.

How do you declare an abstract class in Java?

• abstract ClassName() {}

• class ClassName abstract {}

• class abstract ClassName {}

• abstract class ClassName {}

What is the significance of the 'extends' keyword in Java?

• The 'extends' keyword is used for method overloading in Java.

• The 'extends' keyword is a way to define interfaces in Java.

• The 'extends' keyword signifies class inheritance in Java.

• The 'extends' keyword is used to create static methods in Java.

What is the difference between ArrayList and LinkedList in Java?

• ArrayList is better for random access, while LinkedList is better for frequent insertions and deletions.

• LinkedList is faster for random access than ArrayList.

• ArrayList uses less memory than LinkedList.

• ArrayList allows for dynamic resizing while LinkedList does not.

How can a class implement multiple interfaces in Java?

• A class can implement interfaces by using the 'extends' keyword.

• A class can implement multiple interfaces by using a comma-separated list after the 'implements' keyword.

• A class can implement interfaces only one at a time.

• A class can extend multiple classes using a comma-separated list.

What is method overriding in the context of inheritance?

• Method overriding is a way to create new methods in a class without using inheritance.

• Method overriding is the process of deleting a method from a subclass.

• Method overriding is a feature in inheritance where a subclass redefines a method from its superclass.

• Method overriding is when a superclass redefines a method from its subclass.

The import statement used in Java to access the Scanner class is:

• import java.Scanner;

• import java.util.Scanner;

• import java.package.Scanner

• import.java.util.Scanner;