{"id":951,"date":"2023-06-19T07:30:58","date_gmt":"2023-06-19T13:00:58","guid":{"rendered":"https:\/\/www.codesquadz.com\/blog\/?p=951"},"modified":"2026-10-01T05:50:42","modified_gmt":"2026-10-01T11:20:42","slug":"java-interview-questions","status":"publish","type":"post","link":"https:\/\/www.codesquadz.com\/blog\/java-interview-questions\/","title":{"rendered":"Top 30 Frequently Asked Java Interview Questions"},"content":{"rendered":"\n<p>Whether you are just starting your career or changing jobs, you need to give a job interview. Every interview examines the knowledge base of any job aspirant before hiring anyone. An interviewer chooses to ask some questions to check theoretical as well as practical knowledge.<br><br><\/p>\n\n\n\n<p>Globally, around 10 million Java developers are available, and this number is increasing continuously. The popularity of Java is increasing because it is one of the most common programming languages for developing anyone\u2019s IT career. Java is useful as it is a high-level, object-oriented, and class-based programming language.<br><br>These interview questions bother both freshers and experienced professionals. So we are here to help you out through this article, in which we have compiled 30 frequently asked Java interview questions.<\/p>\n\n\n\n<h2 class=\"has-text-align-left wp-block-heading has-white-color has-vivid-cyan-blue-to-vivid-purple-gradient-background has-text-color has-background has-medium-font-size\" style=\"font-style:normal;font-weight:700;text-transform:capitalize\">30 Commonly Asked Java Interview Questions and Answers<\/h2>\n\n\n\n<p><br>Here are the frequently asked questions in the interview of a Java developer.<br><br><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">1. What is Java?<\/h3>\n\n\n\n<p>Java is a high-level and object-oriented programming language released by Sun Microsystems and built by J. Gosling in 1995. It is a fast, secure, reliable, widely used language helpful in coding applications.<br><br>Java has a virtual machine, the Java Virtual Machine (JVM), that allows Java programs to run on any platform. It comes with a robust community and a comprehensive Java Class Library (JCL).<br><br><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">2. What are the main features of Java?<\/h3>\n\n\n\n<p>Here are the top 5 features of using the Java programming language.<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>Java is easy to use and simple to understand without any technical complexities.<\/li>\n\n\n\n<li>This programming language is architecturally neutral with its \u201cno implementation dependence\u201d feature.\u00a0<\/li>\n\n\n\n<li>It is a portable programming language with the WORA (write once, run anywhere) feature.<\/li>\n\n\n\n<li>Java is platform-independent because it can work on any type of OS and device.<\/li>\n\n\n\n<li>Java is a robust and secure advanced programming language because it uses encryption and decryption.<\/li>\n<\/ol>\n\n\n\n<h3 class=\"wp-block-heading\">3. What is the difference between JDK, JRE, and JVM?<\/h3>\n\n\n\n<p>Java Development Kit (JDK) is a software development kit (SDK), and Java Runtime Environment (JRE) permits Java programs to run. Whereas, the Java Virtual Machine (JVM) is a platform-independent environment to execute bytecode.<br><br><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">4. What is the difference between checked and unchecked exceptions in Java?<br><\/h3>\n\n\n\n<div class=\"is-layout-flex wp-container-2 wp-block-columns\">\n<div class=\"is-layout-flow wp-block-column\"><\/div>\n<\/div>\n\n\n\n<style>\n        \n        table{\n            width: 100%;\n        }\n\n        th{text-align:center;\nbackground-color:blue;\ncolor:white;}\n\n        td{ text-align: left; }\n        table,th,td{\n           border:1px solid black;\n           border-collapse: collapse;\n           padding: 0.5rem 0.5rem;\n        }\n    <\/style>\n\n    <div class=\"container\">\n\n        <table class=\" mt-2\">\n            <thead>\n              <tr>\n                <th>Checked Exceptions<\/th>\n                <th>Unchecked Exceptions<\/th>\n                \n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td>Need to be declared explicitly.<\/td>\n                <td>Don\u2019t need to be declared explicitly.<\/td>\n               \n              <\/tr>\n              <tr>\n                <td>Requires checking by a compiler.<\/td>\n                <td>Doesn\u2019t need to be checked by a compiler.<\/td>\n               \n              <\/tr>\n              <tr>\n                <td>Requires explicit handling using the \u201cthrow\u201d keyword.<\/td>\n                <td>Doesn\u2019t need explicit handling using the \u201cthrow\u201d keyword.<\/td>\n               \n              <\/tr>\n            <\/tbody>\n          <\/table>\n    <\/div>\n\n\n\n<h3 class=\"wp-block-heading\"><br>5. Explain the Java Memory Management system.<\/h3>\n\n\n\n<p>Java memory management is the process of object allocation and deallocation. In Java, you will find <strong>Garbage Collector<\/strong> is a system of searching for &amp; identifying unused heap memory objects and removing or deleting them.<\/p>\n\n\n\n<p><br><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">6. What are the different types of variables in Java?<br><\/h3>\n\n\n\n<p>Java has three types of variables (Local, Static, and Instance).<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Local Variable:<\/strong> A variable declared within a method is called a local variable. This variable is inaccessible from other methods or code blocks.<br><\/li>\n\n\n\n<li><strong>Static or Class Variable:<\/strong> It is a variable declared static using the \u201cstatic\u201d keyword within a class. This variable exists only till the class is loaded in memory and the program is running.<\/li>\n\n\n\n<li><strong>Instance Variable:<\/strong> Any variable declared inside a class but outside a method or block of code. Their existence depends on the existence of any objects they belong to.<\/li>\n<\/ol>\n\n\n\n<h3 class=\"wp-block-heading\"> 7. What is the difference between String, StringBuilder, and StringBuffer?<\/h3>\n\n\n\n<p>In the Java programming language, String, StringBuilder, and StringBuffer differ based on mutability &amp; thread-safe. Here, String &amp; StringBuffer are immutable. However, StringBuilder is immutable.<\/p>\n\n\n\n<p><br>The Performance of String is slow; StringBuffer\u2019s performance is faster than String but slower than StringBuilder. Whereas StringBuilder is the fastest one.<\/p>\n\n\n\n<p><br><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">8. What is the difference between method overloading and method overriding?<br><\/h3>\n\n\n\n<p><br>Method overloading in Java is helpful to improve the readability of a Java program and is performed within a class. On the other hand, Method Overriding in Java is useful to achieve runtime polymorphism and occurs in 2 classes having an inheritance relationship.<\/p>\n\n\n\n<p><br><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">9. What is the significance of the &#8220;final&#8221; keyword in Java?<\/h3>\n\n\n\n<p>The final keyword in Java is helpful to restrict a user by not enabling him to modify a variable, method, or class.<br><br><strong>Final Variable:<\/strong> A variable with the Final keyword can\u2019t be modified.<br>F<strong>inal Method:<\/strong> After making any method Final, you can\u2019t override it.\u00a0<\/p>\n\n\n\n<p><strong>Final Class:<\/strong> It is impossible to extend any class after finalizing it.<br><br><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">10. What is a static method in Java?<\/h3>\n\n\n\n<p>A Static Method in Java is a method to belong to a class (and not the instance of a class). A static method (or class method) can access static variables without using class objects.<br><br><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">11. Explain the concept of abstraction and encapsulation in Java.<\/h3>\n\n\n\n<p><br>Abstraction<strong> <\/strong>and Encapsulation are features of OOP.<br><br><span class=\"has-inline-background\" style=\"background-color:#ffffff\">Abstraction<\/span> is an OOP feature that is well-known to hide unnecessary details (and show important information only). It can resolve an issue only at the design level and focuses on the external view of class or object.<br><br><\/p>\n\n\n\n<p>Encapsulation is also an OOP feature that complements abstraction, which hides code and data into a single unit. It can solve issues at the implementation level and focuses on internal work.<br><br><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">12. What is the difference between an interface and an abstract class?<\/h3>\n\n\n\n<p><br><strong>Interface <\/strong>&amp; <strong>Abstract Class<\/strong> are important concepts of Java and are useful to achieve abstraction. Here are the key differences between these two.<br><\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>An interface has abstract methods. However, an Abstract Class can have abstract and non-abstract methods.<\/li>\n\n\n\n<li>An interface is famous for supporting multiple inheritance, and an Abstract Class is popular as it doesn\u2019t support multiple inheritance.<\/li>\n\n\n\n<li>An interface has static &amp; final variables,<strong> <\/strong>and an Abstract Class can have final, non-final, static, &amp; non-static variables.<\/li>\n\n\n\n<li>Implementation of the Interface is possible using the<strong> \u201c<\/strong>implements\u201d keyword. An Abstract Class can be implemented using the <strong>\u201c<\/strong>extends\u201d<strong> <\/strong>keyword.<\/li>\n<\/ol>\n\n\n\n<h3 class=\"wp-block-heading\">13. What are the access modifiers in Java?<\/h3>\n\n\n\n<p>Access modifiers are keywords to control the visibility of classes, methods, and constructors. In the Java programming language, there are 4 access modifiers that are given here.<br><br><\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Private:<\/strong> It is accessible within the same class and not from outside the class.<\/li>\n\n\n\n<li><strong>Public:<\/strong> It can be accessed within &amp; outside the class and within &amp; outside the package.<\/li>\n\n\n\n<li><strong>Default:<\/strong>\u00a0 Allows access only within the same package (also known as package-private access).<\/li>\n\n\n\n<li><strong>Protected:<\/strong> Access level is within and outside the package using a child class.<\/li>\n<\/ol>\n\n\n\n<h3 class=\"wp-block-heading\">14. How does exception handling work in Java?<\/h3>\n\n\n\n<p><\/p>\n\n\n\n<p><br><\/p>\n\n\n\n<figure class=\"wp-block-embed is-type-rich is-provider-embed-handler wp-block-embed-embed-handler wp-embed-aspect-16-9 wp-has-aspect-ratio\"><div class=\"wp-block-embed__wrapper\">\n<iframe loading=\"lazy\" title=\"Exception Handling In Java With Examples | Java Tutorial | Learn Java with Manish Bhatia\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/6QRAjNfJS5g?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe>\n<\/div><\/figure>\n\n\n\n<p><br><strong>Exception Handling<\/strong> is one of the robust mechanisms in Java to handle runtime errors in it. Here are the steps to define exception handling in Java.<br><br><\/p>\n\n\n\n<p><strong>Step 1:<\/strong> Once an error occurs within the method of a Java programming language, it creates an object (Exception Object). It handles this object in the runtime environment.<\/p>\n\n\n\n<p><strong>Step 2:<\/strong> Here, the runtime system tries to search for an appropriate exception handler to handle the exception.<\/p>\n\n\n\n<p>S<strong>tep 3:<\/strong> The Java runtime environment searches the <strong>call stack<\/strong> to find an appropriate <strong>exception handler<\/strong> to handle the exception.<br><strong>Step 4:<\/strong> Finally, the exception handler catches the exception if the system searches all the methods on the call stack and is unable to find a suitable exception handler.<br><br><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">15. Explain the concept of multithreading in Java.<\/h3>\n\n\n\n<p class=\"has-black-color has-text-color\">Multithreading is a programming concept in Java that is the process of executing multiple threads at once. It is mainly used in gaming, video playing, display animation, and tools like an <strong><a href=\"https:\/\/www.adobe.com\/express\/create\/animation\">animation maker<\/a><\/strong> where smooth performance is essential. It is important as it saves crucial time by performing multiple operations together.<br><br><\/p>\n\n\n\n<blockquote class=\"wp-block-quote\">\n<p class=\"has-vivid-cyan-blue-color has-text-color has-medium-font-size\"><a href=\"https:\/\/www.codesquadz.com\/blog\/8-reasons-learn-java-programming-language-2023\/\" target=\"_blank\" rel=\"noreferrer noopener\"><em><strong>Here are the Top 8 Reasons to Learn Java in 2024<\/strong><\/em><\/a><\/p>\n<\/blockquote>\n\n\n\n<h3 class=\"wp-block-heading\"><br>16. What is a deadlock in Java? How can it be avoided?<\/h3>\n\n\n\n<p>Deadlock in the <a aria-label=\"Java programming language (opens in a new tab)\" class=\"ek-link\" href=\"https:\/\/www.appsquadz.com\/java-development\" target=\"_blank\" rel=\"noreferrer noopener\">Java programming language<\/a> is part of multithreading. Deadlock is a critical situation when 2 or more threads attempt to access the same object that is already acquired by another thread. Indeed, it is crucial to avoid deadlock(s) in Java. However, it is possible with the three unique strategies that are given below.<br><br><\/p>\n\n\n\n<ul class=\"wp-block-list is-style-arrow\">\n<li>Recorder Deadline in Java and recover them which requires frequent checking of the available resources.<\/li>\n\n\n\n<li>Using locks only for the necessary members is required. Here, the unnecessary use of locks leads to a deadlock situation.<\/li>\n\n\n\n<li>Order your resources in Java to prevent circular wait conditions by ensuring that threads always request resources in the same order.&nbsp;<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">17. How does garbage collection work in Java?<\/h3>\n\n\n\n<p>The garbage collector in Java refers to an automatic memory management process. It finds unused objects in memory and removes them to free up space. It works in Java using these methods.<br><br><strong>Mark and Sweep Method<\/strong><\/p>\n\n\n\n<p>This method has a common use in Java that involves two main phases: marking and sweeping. The Garbage Collector marks all objects that are still reachable and scans the entire memory &amp; reclaims object memory that is marked as unreachable.<br><\/p>\n\n\n\n<p><br><\/p>\n\n\n\n<p><strong>Generational Garbage Collection<\/strong><\/p>\n\n\n\n<p>It divides the heap into multiple generations, including the Young &amp; Old generations. Here, all newly created objects are assigned to the Young generation and others to the Old generation.<br><\/p>\n\n\n\n<p><br><\/p>\n\n\n\n<p><strong>Minor and Major Collection<\/strong><\/p>\n\n\n\n<p>Minor or Young collection occurs when the young generation is full and promotes objects to the old generation. Major or old collections occur when the old generation requires them to be reclaimed.<br><br><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">18. What is the difference between a stack and a heap memory in Java?<\/h3>\n\n\n\n<p>For the Java programming language, it is vital to manage memory, which is automatic in Java. Java Virtual Machine (JVM) divides it into 2 parts: Heap Memory and Stack Memory.<br><br><\/p>\n\n\n\n<p><strong>Stack Memory: <\/strong>It is a physical space that is created when a thread is created. It is smaller in size and follows a LIFO Last In, First Out), method. It has less cost with hard implementation.<br><br><\/p>\n\n\n\n<p><strong>Heap Memory:<\/strong> It is created when the application starts and remains till the application runs. It is known for not following any specific order and comes in large sizes, especially when we compare it with Stack Memory. Comparatively, it has a higher cost with easy implementation.<br><br><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">19. Explain the concept of object-oriented programming (OOPs).<\/h3>\n\n\n\n<p>Object-oriented programming (OOPs) in Java is based on classes and objects. OOPs encourage the reuse of objects in the same as well as other programs. Here, the data is available in the form of fields (Attributes) and code in the form of procedures (Methods).<br><\/p>\n\n\n\n<p>The four pillars of OOP are encapsulation, inheritance, polymorphism, and abstraction.<br><br>1. <strong>Encapsulation:<\/strong> It is one of the basic concepts of OOP to bind the data &amp; functions together that operate on that data within a single unit known as a Class.<br><br><\/p>\n\n\n\n<p>2.<strong> Inheritance:<\/strong> Inheritance is one of the key features of OOP. It is a mechanism that empowers a class to derive properties of another class. It permits programmers to reuse the already written code.<br><br><\/p>\n\n\n\n<p>3. <strong>Polymorphism:<\/strong> Polymorphism is the ability of a class to provide several implementations of a method. It has two different types: Compile-time and Runtime<strong> <\/strong>polymorphism.<br><br><\/p>\n\n\n\n<p>4. <strong>Abstraction:<\/strong> Abstraction is an important feature of OOPs, which is simply a method of hiding information details from a user and showing only the functionality of a method to the user.<br><br><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">20. What is the difference between an ArrayList and a LinkedList?<br><\/h3>\n\n\n\n<p>Below are the key differences between ArrayList and LinkedList.<br><br><\/p>\n\n\n\n<style>\n        \n        table{\n            width: 100%;\n        }\n\n        th{text-align:center;\nbackground-color:blue;\ncolor:white;}\n\n        td{ text-align: left; }\n        table,th,td{\n           border:1px solid black;\n           border-collapse: collapse;\n           padding: 0.5rem 0.5rem;\n        }\n    <\/style>\n\n    <div class=\"container\">\n\n        <table class=\" mt-2\">\n            <thead>\n              <tr>\n                <th>ArrayList<\/th>\n                <th>LinkedList<\/th>\n                \n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td>ArrayList is internally implemented as a Dynamic Array for storing the elements.\n<\/td>\n                <td>LinkedList is implemented as a doubly-linked list to store the elements<\/td>\n               \n              <\/tr>\n              <tr>\n                <td>The speed of manipulation with ArrayList is slow.<\/td>\n                <td>The speed of manipulation with LinkedList is faster when compared to ArrayList.<\/td>\n               \n              <\/tr>\n              <tr>\n                <td>Indeed, ArrayList is better for Storing data.<\/td>\n                <td>LinkedList is better when it comes to the manipulation of data.<\/td>\n               \n              <\/tr>\n              <tr>\n                <td>The default capacity is 10 for ArrayList.<\/td>\n                <td>There is no restriction on the capacity of LinkedList.<\/td>\n               \n              <\/tr>\n            <\/tbody>\n          <\/table>\n    <\/div>\n\n\n\n<h3 class=\"wp-block-heading\"><br>21. Does Java support multiple inheritance?<\/h3>\n\n\n\n<p>No, the Java programming language doesn\u2019t support multiple inheritance to avoid creating any ambiguity, like the Diamond Problem. In this problem, one class can inherit the property of another class, or when two or more classes declare a default class with the same property and name.<br><br><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">22. What is the purpose of the &#8220;transient&#8221; keyword in Java?<\/h3>\n\n\n\n<p>In the Java programming language, the \u201ctransient\u201d keyword helps to avoid variable serialization. This keyword avoids the original value of an object and stores only its default value. <br><br><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">23. What is the difference between the &#8220;==&#8221; operator and the &#8220;equals()&#8221; method in Java?<\/h3>\n\n\n\n<p><br>In Java, the \u201c==\u201d Operator and \u201cequals()\u201d methods are helpful for the comparison of two objects. <br>However, they are completely different, and their differences are:<br><br><\/p>\n\n\n\n<style>\n        \n        table{\n            width: 100%;\n        }\n\n        th{text-align:center;\nbackground-color:blue;\ncolor:white;}\n\n        td{ text-align: left; }\n        table,th,td{\n           border:1px solid black;\n           border-collapse: collapse;\n           padding: 0.5rem 0.5rem;\n        }\n    <\/style>\n\n    <div class=\"container\">\n\n        <table class=\" mt-2\">\n            <thead>\n              <tr>\n                <th>==<\/th>\n                <th>equals()<\/th>\n                \n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td>It is an operator<\/td>\n                <td>It is a method<\/td>\n               \n              <\/tr>\n              <tr>\n                <td>Used for Reference Comparison<\/td>\n                <td>Used for Content Comparison<\/td>\n               \n              <\/tr>\n              <tr>\n                <td>Overriding is not allowed<\/td>\n                <td>Overriding is allowed<\/td>\n               \n              <\/tr>\n            <\/tbody>\n          <\/table>\n    <\/div>\n\n\n\n<h3 class=\"wp-block-heading\"><br>24. What are the different types of exceptions in Java?<\/h3>\n\n\n\n<p><br>In the Java programming language, there are 3 types of expectations are:<br><br><strong>Checked Exceptions<\/strong> (also known as Compile-time Exceptions) are the exceptions checked during compile-time by the compiler. The compiler ensures that a programmer handles the exceptions; otherwise, there will be a compilation error.<br><br><\/p>\n\n\n\n<p><strong>Unchecked Exceptions <\/strong>(also known as<strong> <\/strong>Run-Time Exceptions) aren&#8217;t checked at compile time. Most of the time, an error in the programming language causes this exception, and it is a direct subclass of the RuntimeException class.<br><br><\/p>\n\n\n\n<p><strong>User-Defined Exceptions<\/strong><\/p>\n\n\n\n<p>This type of exception occurs when any Java programmer customizes a program using the\u201cthrow keyword\u201d. It is also a result of any error committed at the time of program execution.<br><br><br><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">25. What is the purpose of the &#8220;synchronized&#8221; keyword in Java?<\/h3>\n\n\n\n<p>The \u201cSynchronized\u201d Keyword in the Java programming language is helpful to control access to any shared resource in a multithreaded environment. It helps in maintaining data integrity by preventing multiple threads from modifying the shared data.<br><br><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">26. Explain the concept of method overriding in Java.<\/h3>\n\n\n\n<p><br>In Java, overriding is an important feature that permits a subclass (or child class) to have a method with the same name as declared in the parent class. It is popular for overriding in Java and serves several purposes, including Polymorphism, Specialization, Abstraction, and Code Extension. For method overriding in Java, a method should have the same name and parameters as in the Parent class.<br><\/p>\n\n\n\n<blockquote class=\"wp-block-quote\">\n<p class=\"has-pale-cyan-blue-color has-text-color has-medium-font-size\"><br><em><span style=\"background-color:#ffffff\" class=\"has-inline-background\"><strong>Master Java development by enrolling through our <a aria-label=\"online Java course (opens in a new tab)\" href=\"https:\/\/www.codesquadz.com\/best-java-training-in-noida\" target=\"_blank\" rel=\"noreferrer noopener\" class=\"ek-link\">online Java course<\/a>!<\/strong><\/span><\/em><\/p>\n<\/blockquote>\n\n\n\n<h3 class=\"wp-block-heading\">27. How do you handle errors in Java?<\/h3>\n\n\n\n<p><\/p>\n\n\n\n<p>Here is an overview of how a programmer can handle errors in the Java programming language.<br><br><strong>Try-Catch Block:<\/strong> It permits a programmer to pre-define a code block to be tested for errors in Java. It happens in pairs and defines a code block to be executed.<br><br><\/p>\n\n\n\n<p><strong>Finally Block:<\/strong> It is also an available option for a programmer to use a finally block after a try-catch block. The code it contains will execute even if there are no Java errors (exceptions).<br><br><\/p>\n\n\n\n<p><strong>Throw Exception:<\/strong> A programmer can also use the \u201cthrow\u201d keyword to throw an exception explicitly. It is useful to throw a custom exception (error) in the Java programming language.<br><br><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">28. What is the difference between a constructor and a method in Java?<\/h3>\n\n\n\n<p>In Java, constructors and methods are different; their key differences are:<br><br><\/p>\n\n\n\n<style>\n        \n        table{\n            width: 100%;\n        }\n        th{text-align:center;\nbackground-color:blue;\ncolor:white;}\n        td{ text-align: left; }\n        table,th,td{\n           border:1px solid black;\n           border-collapse: collapse;\n           padding: 0.5rem 0.5rem;\n        }\n    <\/style>\n    <div class=\"container\">\n        <table class=\" mt-2\">\n            <thead>\n              <tr>\n                <th>Constructor<\/th>\n                <th>Method<\/th>\n                \n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td>Used to create and initialize an object\n<\/td>\n                <td>The Method is used for the execution of certain statements.<\/td>\n               \n              <\/tr>\n              <tr>\n                <td>It doesn\u2019t have a return type.<\/td>\n                <td>It has a return type.<\/td>\n               \n              <\/tr>\n              <tr>\n                <<td>Has the same name as the class name.<\/td>\n                <td>The name can be anything.<\/td>\n               \n              <\/tr>\n              <tr>\n                <td>A constructor can\u2019t be inherited by a subclass.<\/td>\n                <td>A method name is the same as the name of a subclass.<\/td>\n               \n              <\/tr>\n            <\/tbody>\n          <\/table>\n    <\/div>\n\n\n\n<h3 class=\"wp-block-heading\"><br>29. How can you prevent a class from being inherited in Java?<\/h3>\n\n\n\n<p>To prevent a class in Java from being inherited, the \u201cFinal\u201d keyword is useful. It is helpful to declare a class as \u201cFinal\u201d and always indicate that it can\u2019t be subclassed.<br><br><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">30. Explain the concept of the Java Virtual Machine (JVM).<\/h3>\n\n\n\n<p>Java Virtual Machine (JVM) is a virtual machine that empowers a computer to run a Java program. It is a specification, implementation, and runtime instance. It can load, verify, and execute code with a class loader as its subsystem. JVM is platform-independent and includes a just-in-time (JIT) compiler.<br><br><\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Conclusion<\/h2>\n\n\n\n<p>These are some of the most frequently asked Java interview questions to help you cover both basic as well as advanced Java concepts. These questions have answers provided by the subject matter experts. It is helpful to kick-start your <a href=\"https:\/\/www.codesquadz.com\/blog\/career-opportunities-after-java-training-scope-salary-2023\/\" class=\"ek-link\">career after completing our Java training<\/a>. Stay tuned to get our next knowledge-rich blog on the most common Digital marketing interview questions.<br><br><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Whether you are just starting your career or changing jobs, you need to give a job interview. Every interview examines the knowledge base of any job aspirant before hiring anyone. An interviewer chooses to ask some questions to check theoretical as well as practical knowledge. Globally, around 10 million Java<\/p>\n","protected":false},"author":3,"featured_media":1021,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[149],"tags":[69,150,151,148,146,152,5],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v19.14 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>30 Frequently Asked Java Interview Questions<\/title>\n<meta name=\"description\" content=\"Prepare for your next Java interview with a comprehensive blog featuring top 30 frequently asked Java interview questions and answers.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.codesquadz.com\/blog\/java-interview-questions\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"30 Frequently Asked Java Interview Questions\" \/>\n<meta property=\"og:description\" content=\"Prepare for your next Java interview with a comprehensive blog featuring top 30 frequently asked Java interview questions and answers.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.codesquadz.com\/blog\/java-interview-questions\/\" \/>\n<meta property=\"og:site_name\" content=\"CodeSquadz\" \/>\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/appsquadzeducation\" \/>\n<meta property=\"article:author\" content=\"https:\/\/www.facebook.com\/codesquadz\" \/>\n<meta property=\"article:published_time\" content=\"2023-06-19T13:00:58+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2026-10-01T11:20:42+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.codesquadz.com\/blog\/wp-content\/uploads\/java-interview-questions.png\" \/>\n\t<meta property=\"og:image:width\" content=\"700\" \/>\n\t<meta property=\"og:image:height\" content=\"400\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/png\" \/>\n<meta name=\"author\" content=\"Soniya Tonger\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:creator\" content=\"@appsquadzedu\" \/>\n<meta name=\"twitter:site\" content=\"@appsquadzedu\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Soniya Tonger\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"13 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":[\"Article\",\"BlogPosting\"],\"@id\":\"https:\/\/www.codesquadz.com\/blog\/java-interview-questions\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/www.codesquadz.com\/blog\/java-interview-questions\/\"},\"author\":{\"name\":\"Soniya Tonger\",\"@id\":\"https:\/\/www.codesquadz.com\/blog\/#\/schema\/person\/06a66fef13ec830de6f5b235a44d22d1\"},\"headline\":\"Top 30 Frequently Asked Java Interview Questions\",\"datePublished\":\"2023-06-19T13:00:58+00:00\",\"dateModified\":\"2026-10-01T11:20:42+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/www.codesquadz.com\/blog\/java-interview-questions\/\"},\"wordCount\":2650,\"commentCount\":0,\"publisher\":{\"@id\":\"https:\/\/www.codesquadz.com\/blog\/#organization\"},\"keywords\":[\"java\",\"java concepts\",\"java course\",\"java developer\",\"java interview questions\",\"java questions answers\",\"java training\"],\"articleSection\":[\"Interview Questions\"],\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"CommentAction\",\"name\":\"Comment\",\"target\":[\"https:\/\/www.codesquadz.com\/blog\/java-interview-questions\/#respond\"]}]},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.codesquadz.com\/blog\/java-interview-questions\/\",\"url\":\"https:\/\/www.codesquadz.com\/blog\/java-interview-questions\/\",\"name\":\"30 Frequently Asked Java Interview Questions\",\"isPartOf\":{\"@id\":\"https:\/\/www.codesquadz.com\/blog\/#website\"},\"datePublished\":\"2023-06-19T13:00:58+00:00\",\"dateModified\":\"2026-10-01T11:20:42+00:00\",\"description\":\"Prepare for your next Java interview with a comprehensive blog featuring top 30 frequently asked Java interview questions and answers.\",\"breadcrumb\":{\"@id\":\"https:\/\/www.codesquadz.com\/blog\/java-interview-questions\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/www.codesquadz.com\/blog\/java-interview-questions\/\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/www.codesquadz.com\/blog\/java-interview-questions\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/www.codesquadz.com\/blog\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Top 30 Frequently Asked Java Interview Questions\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/www.codesquadz.com\/blog\/#website\",\"url\":\"https:\/\/www.codesquadz.com\/blog\/\",\"name\":\"CodeSquadz\",\"description\":\"Top Institute for IT Training Courses\",\"publisher\":{\"@id\":\"https:\/\/www.codesquadz.com\/blog\/#organization\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/www.codesquadz.com\/blog\/?s={search_term_string}\"},\"query-input\":\"required name=search_term_string\"}],\"inLanguage\":\"en-US\"},{\"@type\":\"Organization\",\"@id\":\"https:\/\/www.codesquadz.com\/blog\/#organization\",\"name\":\"CodeSquadz\",\"url\":\"https:\/\/www.codesquadz.com\/blog\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/www.codesquadz.com\/blog\/#\/schema\/logo\/image\/\",\"url\":\"https:\/\/www.codesquadz.com\/blog\/wp-content\/uploads\/codesquadz-logo.png\",\"contentUrl\":\"https:\/\/www.codesquadz.com\/blog\/wp-content\/uploads\/codesquadz-logo.png\",\"width\":250,\"height\":67,\"caption\":\"CodeSquadz\"},\"image\":{\"@id\":\"https:\/\/www.codesquadz.com\/blog\/#\/schema\/logo\/image\/\"},\"sameAs\":[\"https:\/\/www.youtube.com\/channel\/UCoIaFBueC3YCIXXDEVVR91A\",\"https:\/\/www.linkedin.com\/company\/77038456\/admin\/\",\"https:\/\/www.instagram.com\/appsquadzeducation\/\",\"https:\/\/in.pinterest.com\/appsquadzeducation\/\",\"https:\/\/www.facebook.com\/appsquadzeducation\",\"https:\/\/twitter.com\/appsquadzedu\"]},{\"@type\":\"Person\",\"@id\":\"https:\/\/www.codesquadz.com\/blog\/#\/schema\/person\/06a66fef13ec830de6f5b235a44d22d1\",\"name\":\"Soniya Tonger\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/www.codesquadz.com\/blog\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/secure.gravatar.com\/avatar\/ce0d63c3b23fba6742a442760d76ba49?s=96&d=mm&r=g\",\"contentUrl\":\"https:\/\/secure.gravatar.com\/avatar\/ce0d63c3b23fba6742a442760d76ba49?s=96&d=mm&r=g\",\"caption\":\"Soniya Tonger\"},\"description\":\"CodeSquadz is a leading Java training institute in Noida, India with a focus on training students in various languages. We provide immersive training programs for Core &amp; Advanced Java, Springboot, Python, PHP, Hibernate languages and Digital Marketing.\",\"sameAs\":[\"https:\/\/www.codesquadz.com\/\",\"https:\/\/www.facebook.com\/codesquadz\",\"https:\/\/www.instagram.com\/codesquadz\/\",\"https:\/\/in.pinterest.com\/codesquadz\/\"],\"url\":\"https:\/\/www.codesquadz.com\/blog\/author\/abhijeet\/\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"30 Frequently Asked Java Interview Questions","description":"Prepare for your next Java interview with a comprehensive blog featuring top 30 frequently asked Java interview questions and answers.","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.codesquadz.com\/blog\/java-interview-questions\/","og_locale":"en_US","og_type":"article","og_title":"30 Frequently Asked Java Interview Questions","og_description":"Prepare for your next Java interview with a comprehensive blog featuring top 30 frequently asked Java interview questions and answers.","og_url":"https:\/\/www.codesquadz.com\/blog\/java-interview-questions\/","og_site_name":"CodeSquadz","article_publisher":"https:\/\/www.facebook.com\/appsquadzeducation","article_author":"https:\/\/www.facebook.com\/codesquadz","article_published_time":"2023-06-19T13:00:58+00:00","article_modified_time":"2026-10-01T11:20:42+00:00","og_image":[{"width":700,"height":400,"url":"https:\/\/www.codesquadz.com\/blog\/wp-content\/uploads\/java-interview-questions.png","type":"image\/png"}],"author":"Soniya Tonger","twitter_card":"summary_large_image","twitter_creator":"@appsquadzedu","twitter_site":"@appsquadzedu","twitter_misc":{"Written by":"Soniya Tonger","Est. reading time":"13 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":["Article","BlogPosting"],"@id":"https:\/\/www.codesquadz.com\/blog\/java-interview-questions\/#article","isPartOf":{"@id":"https:\/\/www.codesquadz.com\/blog\/java-interview-questions\/"},"author":{"name":"Soniya Tonger","@id":"https:\/\/www.codesquadz.com\/blog\/#\/schema\/person\/06a66fef13ec830de6f5b235a44d22d1"},"headline":"Top 30 Frequently Asked Java Interview Questions","datePublished":"2023-06-19T13:00:58+00:00","dateModified":"2026-10-01T11:20:42+00:00","mainEntityOfPage":{"@id":"https:\/\/www.codesquadz.com\/blog\/java-interview-questions\/"},"wordCount":2650,"commentCount":0,"publisher":{"@id":"https:\/\/www.codesquadz.com\/blog\/#organization"},"keywords":["java","java concepts","java course","java developer","java interview questions","java questions answers","java training"],"articleSection":["Interview Questions"],"inLanguage":"en-US","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/www.codesquadz.com\/blog\/java-interview-questions\/#respond"]}]},{"@type":"WebPage","@id":"https:\/\/www.codesquadz.com\/blog\/java-interview-questions\/","url":"https:\/\/www.codesquadz.com\/blog\/java-interview-questions\/","name":"30 Frequently Asked Java Interview Questions","isPartOf":{"@id":"https:\/\/www.codesquadz.com\/blog\/#website"},"datePublished":"2023-06-19T13:00:58+00:00","dateModified":"2026-10-01T11:20:42+00:00","description":"Prepare for your next Java interview with a comprehensive blog featuring top 30 frequently asked Java interview questions and answers.","breadcrumb":{"@id":"https:\/\/www.codesquadz.com\/blog\/java-interview-questions\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.codesquadz.com\/blog\/java-interview-questions\/"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/www.codesquadz.com\/blog\/java-interview-questions\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.codesquadz.com\/blog\/"},{"@type":"ListItem","position":2,"name":"Top 30 Frequently Asked Java Interview Questions"}]},{"@type":"WebSite","@id":"https:\/\/www.codesquadz.com\/blog\/#website","url":"https:\/\/www.codesquadz.com\/blog\/","name":"CodeSquadz","description":"Top Institute for IT Training Courses","publisher":{"@id":"https:\/\/www.codesquadz.com\/blog\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.codesquadz.com\/blog\/?s={search_term_string}"},"query-input":"required name=search_term_string"}],"inLanguage":"en-US"},{"@type":"Organization","@id":"https:\/\/www.codesquadz.com\/blog\/#organization","name":"CodeSquadz","url":"https:\/\/www.codesquadz.com\/blog\/","logo":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.codesquadz.com\/blog\/#\/schema\/logo\/image\/","url":"https:\/\/www.codesquadz.com\/blog\/wp-content\/uploads\/codesquadz-logo.png","contentUrl":"https:\/\/www.codesquadz.com\/blog\/wp-content\/uploads\/codesquadz-logo.png","width":250,"height":67,"caption":"CodeSquadz"},"image":{"@id":"https:\/\/www.codesquadz.com\/blog\/#\/schema\/logo\/image\/"},"sameAs":["https:\/\/www.youtube.com\/channel\/UCoIaFBueC3YCIXXDEVVR91A","https:\/\/www.linkedin.com\/company\/77038456\/admin\/","https:\/\/www.instagram.com\/appsquadzeducation\/","https:\/\/in.pinterest.com\/appsquadzeducation\/","https:\/\/www.facebook.com\/appsquadzeducation","https:\/\/twitter.com\/appsquadzedu"]},{"@type":"Person","@id":"https:\/\/www.codesquadz.com\/blog\/#\/schema\/person\/06a66fef13ec830de6f5b235a44d22d1","name":"Soniya Tonger","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.codesquadz.com\/blog\/#\/schema\/person\/image\/","url":"https:\/\/secure.gravatar.com\/avatar\/ce0d63c3b23fba6742a442760d76ba49?s=96&d=mm&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/ce0d63c3b23fba6742a442760d76ba49?s=96&d=mm&r=g","caption":"Soniya Tonger"},"description":"CodeSquadz is a leading Java training institute in Noida, India with a focus on training students in various languages. We provide immersive training programs for Core &amp; Advanced Java, Springboot, Python, PHP, Hibernate languages and Digital Marketing.","sameAs":["https:\/\/www.codesquadz.com\/","https:\/\/www.facebook.com\/codesquadz","https:\/\/www.instagram.com\/codesquadz\/","https:\/\/in.pinterest.com\/codesquadz\/"],"url":"https:\/\/www.codesquadz.com\/blog\/author\/abhijeet\/"}]}},"_links":{"self":[{"href":"https:\/\/www.codesquadz.com\/blog\/wp-json\/wp\/v2\/posts\/951"}],"collection":[{"href":"https:\/\/www.codesquadz.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.codesquadz.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.codesquadz.com\/blog\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.codesquadz.com\/blog\/wp-json\/wp\/v2\/comments?post=951"}],"version-history":[{"count":87,"href":"https:\/\/www.codesquadz.com\/blog\/wp-json\/wp\/v2\/posts\/951\/revisions"}],"predecessor-version":[{"id":1873,"href":"https:\/\/www.codesquadz.com\/blog\/wp-json\/wp\/v2\/posts\/951\/revisions\/1873"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.codesquadz.com\/blog\/wp-json\/wp\/v2\/media\/1021"}],"wp:attachment":[{"href":"https:\/\/www.codesquadz.com\/blog\/wp-json\/wp\/v2\/media?parent=951"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.codesquadz.com\/blog\/wp-json\/wp\/v2\/categories?post=951"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.codesquadz.com\/blog\/wp-json\/wp\/v2\/tags?post=951"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}