Mastering Java Concepts

What is the main method signature in Java?

• public void main(String[] args)

• public static void main(String[] args)

• public static main(String[] args)

• static void main(String args)

Which of the following is a valid variable declaration in Java?

• string number;

• int number;

• float number;

• int 1number;

What is the default value of a boolean variable in Java?

• false

• 1

• null

• true

What keyword is used to create a class in Java?

• instantiate

• define

• create

• class

What is the purpose of the 'this' keyword in Java?

• The 'this' keyword is used to define static methods.

• The 'this' keyword is used to access global variables.

• The 'this' keyword is used to create new classes.

• The 'this' keyword is used to refer to the current object instance.

What is inheritance in object-oriented programming?

• Inheritance is a technique for managing memory allocation.

• Inheritance is a method for data encryption.

• Inheritance is a way to create new programming languages.

• Inheritance allows a subclass to inherit attributes and methods from a superclass.

What is polymorphism in Java?

• Polymorphism is the ability to create multiple classes in Java.

• Polymorphism is the ability of a single function or method to operate in different ways based on the object it is acting upon.

• Polymorphism is the method of overriding a function in Java.

• Polymorphism refers to the process of compiling Java code into bytecode.

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

• An interface cannot provide any implementation and supports multiple inheritance, while an abstract class can provide some implementation and supports single inheritance.

• An interface can only be used in a single class and cannot extend other interfaces.

• An abstract class cannot have any methods and supports multiple inheritance.

• An interface can provide implementation and supports single inheritance.

How do you handle exceptions in Java?

• Use if-else statements to handle exceptions in Java.

• Throw exceptions without catching them.

• Ignore exceptions and continue execution.

• Use try-catch blocks to handle exceptions in Java.

What is the purpose of the try-catch block?

• To define variables in a function.

• To optimize performance of the program.

• To improve code readability.

• To handle exceptions and prevent program crashes.