Prepare for These 9 Critical Java Interview Questions in 2024

Java is among the most used programming languages, and a job placement or hire is almost all about how good one performs in answering tough interview questions. Whether Java developer or a fresher, it makes all the difference in being well-prepared. If you are taking Java Training in Coimbatore, then you will get a rock-solid understanding of Java that is most important to handle the tricky technical questions asked in interviews. So let us dive into These 9 critical Java interview questions in 2024 that can help you stand out in interviews.

Remember, the knowledge of Java is just half the battle; you have to prove problem-solving abilities and knowledge in the important concepts of Java. So if you are targeting high for excellence in Java Training in Coimbatore then, here’s your way for further success.

Well, it’s true; practicing coding exercises is helpful, but the lack of proper concepts on your part and unpreparedness for some commonly asked interview questions does not work for you to ace interviews. Let’s go ahead and get into the top questions you should be prepared for in 2024 along with much detail for explanation.

1. What are the key features of Java?

This actually is one of the most frequently asked Java interview questions, usually in the preliminary stages of the recruitment process. That’s why Java is so widely used-that is due to a number of pretty useful features that it provides. Here’s how you can answer that:

Important Features of Java :

• Object-Oriented: Everything in Java works using objects and classes. This feature allows for more structured and reusable code.

• Platform-Independent: Java’s “Write Once, Run Anywhere” principle. It is compiled into bytecode and can run on any machine with a Java Virtual Machine (JVM).

• Multithreading: Java supports multithreading, which allows the system to execute two or more threads simultaneously. Therefore, it is ideal for games, animation, or real-time applications.

• Memory Management: Java provides an automatic garbage collection feature, which helps free up memory occupied by objects that are no longer in use.

• Security: Java has very strong security provisions, including bytecode verification at load time and also runtime security checks in addition to encryption.

2. Explain the Difference Between JDK, JRE, and JVM

• JDK: The abbreviation JDK for Java Development Kit stands for software development for developing applications using the Java programming language. It comprises the JRE and software development tools, like a compiler, debugger, and JavaDoc.

• JRE: JRE provides the library along with other constituents which carry the JVM along in order to operate Java application. However it does not consist of any of Java development tools like in JDK.

• JVM – It is the runtime of Java bytecode, basically acting as an interpreter between the Java code and the hardware at which the machine operates. JVM is platform-specific but the programs developed in Java can run anywhere because JVM has platform-independence.

In your Java Training in Coimbatore, you will learn more about all these, allowing you to understand the development and runtime environment for developing Java applications.

3. What is the difference between HashMap and Hashtable?

HashMap and Hashtable are two of the most widely used structures in Java, and knowing about differences will prove helpful, especially when dealing with collections.

Differences Based on Key Aspects:

• Synchronization: HashMap is not synchronized or thread safe. It may be accessed from multiple threads concurrently, whereas Hashtable is a synchronous one, meaning that it is locked-in at all possible states.

• Null Keys and Values: HashMap accepts one null key and any number of null values whereas Hashtable does not accept any null key or value.

• Performance: A HashMap is generally faster than a Hashtable since the HashMap class is not synchronized. The overhead for synchronization makes the Hashtable relatively slower in terms of performance.

• Legacy: A HashMap was first implemented in Java 1.2 as part of the Java Collections Framework whereas Hashtable dates back and is considered as legacy class.

Now, you get the best software training institute in Coimbatore with placement and learn the hands-on usage of the classes in such a way that you will learn when and where to apply each one.

4. What is Inheritance in Java?

It is a mechanism in Java where one class-the child or the subclass-inherits fields and methods of another class-the parent or superclass. Code reusability, along with method overriding, is possible because of inheritance.

Types of Inheritance in Java:

• Single Inheritance: A class inherits from only one superclass.

• Multilevel Inheritance: A class inherits from a class that is itself a subclass of another class.

• Hierarchical Inheritance: Several classes inherit from a single superclass.

Java does not support multiple inheritance (where a class can inherit from more than one class) to avoid complexity and the “diamond problem.”

Example :

5. What Are Java Streams?

Java streams are part of the java.util.stream package. The Java stream API was first introduced in Java 8. It is a feature that lets you perform functional-style operations on collections and other sequences of data

Key Points :

• Streams don’t store data but operate on the source (collections, arrays, etc.).

• Streams support sequential and parallel operations.

Example :

This code snippet filters and prints names starting with “J” using a stream.

6. How Does Exception Handling Work in Java?

• Try Block This can be a block of code that may throw an exception. This block is surrounded by the try block.

• Catch Block: This catch block handles the exceptions that occur.

• Finally Block: This block is always executed, regardless of an exception having occurred or not.

• Throw: The keyword throw is used to explicitly throw an exception.
  The throws keyword is used in the declarations of methods to indicate that a method may throw certain exceptions.

Example :

7. Java Memory Model (Heap vs Stack)

In Java, memory is divided into two major areas – the heap and the stack.

Heap The heap is used for dynamic memory allocation. The storage of objects and the instance variables are kept in the heap. Java garbage collector controls the heap.

Stack: The stack is used for static memory allocation. It stores method calls, local variables, and references to objects in the heap. For each method call, a new stack frame is added.

Key Points:

• Primitive types as well as references to objects are held within the stack

• Objects themselves are in the heap

• Memory allocation is quicker in the stack, although the heap is slower, but can hold more data.

8. What is Polymorphism in Java?

What polymorphism does is, it allows using one interface or method for different types of objects. In other words, polymorphism is used to improve the flexibility and reusability of code.

Types of Polymorphism :

• Compile-time Polymorphism (Method Overloading): Multiple methods with the same name but different parameters exist in the same class.
• Runtime Polymorphism (Method Overriding): A subclass provides a specific implementation of a method that is already defined in its superclass.

Example of Overloading:

Example of Overriding:

9. What are functional interfaces in Java?

A functional interface is a kind of interface that has only one abstract method. However, it can have any number of default or static methods. Functional interfaces represent the backbone of lambda expressions.

Example :

Lambda expressions can be used to instantiate functional interfaces, simplifying code and making it more readable.

Example Using Lambda :

This feature makes Java more powerful and expressive.

Here are the top nine critical Java interview questions that you need to prepare for 2024. Whether it is an experienced developer or a fresher, proper preparation gives one a solid edge in the interview process. If you want to enhance your Java skills, then join Xplore It Corp and earn the best for training. Their comprehensive courseware programs both for novices and more advanced learners, provide you with the experience of learning from professionals who will definitely make you answer anything with bold confidence.