Java Mcq Interview Questions
Reinforce Your Knowledge: Java Interview Questions and Answers
Java MCQ interview questions are multiple choice questions that are asked during a Java programming language job interview. They cover various topics such as core concepts, object-oriented programming, data types, collections, exception handling, and more. These questions are designed to assess a candidate's knowledge and understanding of Java in a short and structured format. They are used by employers to evaluate a candidate's technical skills, problem-solving abilities, and familiarity with Java concepts and syntax. A strong performance on these questions can increase the chances of landing a job in the field of Java development.
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1 - What is Java?
Java is a high-level, object-oriented programming language that was developed by Sun Microsystems in 1995. It is designed to be platform-independent, meaning that it can run on any device with a Java Virtual Machine (JVM). Java is used for a wide range of applications, from web development to mobile and desktop applications.
2) What are the key features of Java?
Some key features of Java include its simplicity, ease of use, and platform independence. It also has automatic memory management, which helps developers to focus on writing code rather than managing memory. Additionally, Java is secure and provides strong protection against viruses, hacking, and other security threats.
3) What is the difference between a class and an object?
A class in Java is a blueprint or template for creating objects. It contains the variables and methods that define the behavior of objects. Objects, on the other hand, are instances of a class. They have their own state and behavior, based on the class from which they are created.
4) What is the difference between an interface and a class?
A class is a blueprint for creating objects, whereas an interface is a template for implementing certain behaviors. A class can have both method implementations and attributes, while an interface only has method signatures. Additionally, a class can only extend one other class, but it can implement multiple interfaces.
5) What is inheritance in Java?
Inheritance is the mechanism by which a class can inherit the properties and methods of another class. It allows for code reuse and helps to create more efficient and organized code. In Java, a sub class can inherit from a parent class using the “extends” keyword.
6) How is polymorphism achieved in Java?
Polymorphism in Java is achieved through method overriding and method overloading. Method overriding allows a subclass to provide its own implementation of a method from its superclass. Method overloading allows developers to have multiple methods with the same name but different parameters.
7) What is the difference between a static and non-static method?
A static method is a method that can be accessed without creating an instance of the class. It is often used for utility methods and is called using the class name. Non-static methods, on the other hand, can only be called on an instance of the class.
8) What is a constructor in Java?
A constructor in Java is a special method that is used to initialize objects. It is called when an instance of a class is created, and it is responsible for setting initial values for the object's variables. Constructors can have parameters, and they must have the same name as the class.
9) What is the difference between a break and continue statement?
A break statement is used to terminate a loop, while a continue statement is used to skip over the current iteration of a loop and continue with the next iteration. Break statements are commonly used in switch statements, while continue statements are commonly used in loops.
10) What is the use of the “super” keyword in Java?
The “super” keyword in Java is used to access or call methods and variables from the parent class. It is also used in constructors to call the constructor of the parent class. This is useful in cases where the parent class has a constructor with parameters that need to be called.
11) What is a package in Java?
A package in Java is a way to organize and group related classes and interfaces. It helps to avoid naming conflicts and simplify the development process. Packages are also used for access control, as classes within a package can only be accessed by other classes in the same package unless specified otherwise.
12) What is the difference between a String and StringBuilder?
A String in Java is an immutable object, meaning it cannot be changed after it is created. StringBuilder, on the other hand, is a mutable object that allows for the modification of strings. This makes StringBuilder more efficient for tasks that require frequent string modifications.
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13) What is the difference between a HashSet and a TreeSet?
A HashSet in Java is an unordered collection of distinct objects, while a TreeSet is an ordered collection that does not allow duplicates. HashSet is typically faster for adding and retrieving items, while TreeSet is faster for checking if an item exists.
14) What is an exception in Java?
An exception in Java is an event that occurs during the execution of a program that disrupts the normal flow of the program. This can include errors, such as divide by zero or accessing an invalid index in an array. Exceptions can be handled using try-catch blocks to prevent the program from crashing.
15) What is the difference between a Checked and Unchecked Exception?
Checked exceptions in Java are those that must be handled or declared in the code, while unchecked exceptions do not need to be explicitly handled. This means that a try-catch block is not required for unchecked exceptions, but it is still possible to handle them if desired. Examples of checked exceptions include IOExceptions, while unchecked exceptions include NullPointerExceptions.
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