Java
Top 250 Java Interview Questions and Answers 2024
250 questions found
Updated 14 Dec 2024
Q201. What are the java 1.8 features?
Java 1.8 introduced several new features including lambda expressions, functional interfaces, streams, and default methods.
Lambda expressions allow you to write code in a more concise and readable way.
Functional interfaces are interfaces with a single abstract method, used for lambda expressions.
Streams provide a way to work with sequences of elements and perform operations on them.
Default methods allow interfaces to have method implementations.
Other features include the new ...read more
Q202. what is dependency injection in spring
Dependency injection in Spring is a design pattern where objects are provided with their dependencies rather than creating them internally.
In Spring, dependency injection is achieved through either constructor injection or setter injection.
It helps in achieving loose coupling between classes and promotes easier testing and maintenance.
Example: In Spring framework, you can define dependencies in a configuration file and let the framework inject them into the classes at runtime...read more
Q203. Explain Java OPPs concept.
Java OPPs concept refers to Object-Oriented Programming principles in Java.
Java OPPs involves concepts like classes, objects, inheritance, polymorphism, and encapsulation.
Classes are blueprints for objects, defining attributes and behaviors.
Inheritance allows a class to inherit attributes and methods from another class.
Polymorphism enables objects to be treated as instances of their parent class.
Encapsulation involves bundling data and methods within a class to restrict acces...read more
Q204. Coding questions. Add digits of an integer using streams.
Add digits of an integer using streams.
Convert the integer to a string
Split the string into individual characters
Convert each character back to an integer
Sum all the integers using streams
Q205. Coding part in kotlin or java
Both Kotlin and Java can be used for coding in Android development.
Both Kotlin and Java are officially supported languages for Android development.
Kotlin is preferred by many developers for its concise syntax and reduced boilerplate code.
Java is still widely used in existing Android projects and has a larger pool of resources and libraries.
Developers can choose between Kotlin and Java based on their familiarity and project requirements.
Q206. springboot annotations and their usecases
SpringBoot annotations are used to simplify the development process by providing shortcuts for common tasks.
Annotations like @RestController, @RequestMapping, @GetMapping, @PostMapping are used to define RESTful web services.
Annotations like @Service, @Repository, @Component are used for defining beans.
Annotations like @Autowired, @Qualifier are used for dependency injection.
Annotations like @Transactional are used for managing transactions.
Annotations like @Value, @Configura...read more
Q207. Javaproject you have done
Developed a Java project for a school assignment on implementing a library management system.
Used Java programming language to create classes for books, users, and transactions
Implemented features such as adding/removing books, checking out books, and generating reports
Utilized JDBC for database connectivity to store book and user information
Q208. Design patterns and their applications in Java frameworks
Design patterns are reusable solutions to common software problems. Java frameworks use various design patterns to improve code quality and maintainability.
Java frameworks like Spring and Hibernate use the Singleton pattern to ensure only one instance of a class is created.
The Factory pattern is used to create objects without exposing the creation logic to the client.
The Observer pattern is used to notify multiple objects when a change occurs in a subject object.
The Decorator...read more
Java Jobs
Q209. return type for get window handles
The return type for get window handles is an array of strings.
Return type should be an array of strings
Each string in the array represents a window handle
Example: ['handle1', 'handle2', 'handle3']
Q210. Functional interface in java?
Functional interface in Java is an interface with only one abstract method. It can have multiple default or static methods.
Functional interfaces can be annotated with @FunctionalInterface to ensure they have only one abstract method.
Examples of functional interfaces in Java include Runnable, Callable, and ActionListener.
Lambda expressions can be used to implement functional interfaces concisely.
Q211. Data structures in java
Data structures in Java are used to store and organize data efficiently.
Java provides built-in data structures like arrays, lists, sets, maps, queues, and stacks.
Arrays are used to store a fixed-size collection of elements of the same data type.
Lists like ArrayList and LinkedList can dynamically grow and shrink in size.
Sets ensure unique elements and maps store key-value pairs.
Queues follow the FIFO (First In First Out) principle, while stacks follow the LIFO (Last In First O...read more
Q212. What is Java and what is role in it
Java is a high-level programming language used for developing applications and software.
Java is an object-oriented language
It is platform-independent
It is used for developing web, mobile, and desktop applications
Java is used in Android app development
Java is used for creating server-side applications
Java is used for developing enterprise-level applications
Q213. How would you rate yourself in C and Java?
I would rate myself as proficient in both C and Java.
I have extensive experience in both languages, having worked on multiple projects using them.
I am comfortable with the syntax and can write efficient and optimized code.
I am familiar with the standard libraries and can use them effectively.
I am always learning and improving my skills in both languages.
For example, in C, I have worked on projects involving embedded systems and low-level programming, while in Java, I have dev...read more
Q214. What are the different between c++ and java
C++ is a compiled language while Java is an interpreted language.
C++ is faster and more efficient than Java.
Java is platform-independent while C++ is platform-dependent.
C++ allows for manual memory management while Java has automatic garbage collection.
Java has built-in support for multithreading while C++ requires external libraries.
C++ is commonly used for system-level programming while Java is used for web and mobile applications.
Q215. Difference between @Controller, @RestController
Difference between @Controller and @RestController
Both are used for handling HTTP requests in Spring framework
@Controller returns a view while @RestController returns data in JSON/XML format
@RestController is a combination of @Controller and @ResponseBody annotations
Use @Controller for traditional web applications and @RestController for RESTful web services
Q216. What are the new features added to java8
Java8 introduced several new features including lambda expressions, streams, and default methods.
Lambda expressions allow for functional programming and simplify code.
Streams provide a way to process collections of data in a functional way.
Default methods allow for adding new methods to interfaces without breaking existing implementations.
Other features include the Date and Time API, Nashorn JavaScript engine, and improved security.
Java8 also introduced the concept of Optiona...read more
Q217. What is the differences between Java and Python?
Java is statically typed, object-oriented language with a focus on performance and scalability. Python is dynamically typed, high-level language known for its simplicity and readability.
Java is statically typed, meaning variable types are explicitly declared at compile time. Python is dynamically typed, allowing for more flexibility but potentially leading to runtime errors.
Java is more verbose and requires more boilerplate code compared to Python, which emphasizes readabilit...read more
Q218. Explain @SprintBootApplication annotation.
Annotation used in Spring Boot to enable the application to be run from a main method.
Used to mark a class as the main entry point for a Spring Boot application
Eliminates the need for a traditional main method
Can be used in combination with @SpringBootApplication annotation
Q219. What is javascript? What is the difference between Java and Javascript?
JavaScript is a programming language commonly used for web development. It is different from Java in terms of syntax, purpose, and usage.
JavaScript is a scripting language primarily used for client-side web development.
Java is a general-purpose programming language often used for server-side applications.
JavaScript code is executed on the client's browser, while Java code is executed on the server.
JavaScript is dynamically typed, while Java is statically typed.
JavaScript is o...read more
Q220. What are new features in java 17
Java 17 introduces new features like Sealed Classes, Pattern Matching for switch, and Foreign Function & Memory API.
Sealed Classes allow restricting which classes can be subclasses of a superclass.
Pattern Matching for switch simplifies code by combining conditional logic with variable assignment.
Foreign Function & Memory API enables Java programs to interoperate with code written in other languages.
Q221. What is bean factory?
Bean factory is a container for managing beans in Spring framework.
Bean factory is responsible for creating, managing, and configuring beans in a Spring application.
It uses inversion of control (IoC) to manage the beans.
Beans are defined in a configuration file (XML or Java) and the bean factory instantiates them.
Example: ApplicationContext is a type of bean factory in Spring framework.
Q222. What is java opps
Java OOPs (Object-Oriented Programming) is a programming paradigm based on the concept of objects, which can contain data in the form of fields and code in the form of procedures.
Java OOPs focuses on creating objects that interact with each other to solve a problem.
Key principles of Java OOPs include Inheritance, Encapsulation, Polymorphism, and Abstraction.
Example: Inheritance allows a class to inherit properties and behavior from another class, promoting code reusability.
Q223. All Spring annotation.
Spring annotations are used to provide metadata to Spring framework classes and methods.
Annotations are used to configure Spring beans, dependency injection, AOP, etc.
Examples include @Component, @Autowired, @RequestMapping, @Transactional, etc.
Q224. pattern in java
Pattern in Java refers to a design pattern used to solve common problems in software development.
Design patterns help in creating reusable and maintainable code.
Examples of design patterns in Java include Singleton, Factory, and Observer.
Each design pattern has a specific purpose and structure to follow.
Q225. Functional interface - what is use of static and default in real time
Static and default methods in functional interfaces provide utility methods and default implementations for interface methods in real-time applications.
Static methods in functional interfaces can be used for utility methods that are not tied to a specific instance of the interface.
Default methods in functional interfaces provide default implementations for interface methods, allowing for backward compatibility when new methods are added to the interface.
In real-time applicati...read more
Q226. What is C++ Java
C++ and Java are programming languages used for software development.
C++ is a high-performance language used for system programming, game development, and other performance-critical applications.
Java is an object-oriented language used for developing web applications, mobile apps, and enterprise software.
C++ is compiled, while Java is both compiled and interpreted.
C++ allows for direct memory manipulation, while Java has automatic memory management.
C++ is known for its speed ...read more
Q227. Difference between Java and C language.
Java is an object-oriented programming language while C is a procedural programming language.
Java is platform-independent while C is platform-dependent.
Java has automatic memory management while C requires manual memory management.
Java has built-in support for multithreading while C requires external libraries for multithreading.
Java has a larger standard library compared to C.
Java is used for developing web applications, mobile applications, and enterprise software while C i...read more
Q228. What are the 2 difference between c++ and java
C++ is a compiled language while Java is an interpreted language.
C++ is faster than Java due to its compilation process.
Java has automatic garbage collection while C++ requires manual memory management.
C++ supports multiple inheritance while Java only supports single inheritance.
Java has a built-in exception handling mechanism while C++ requires manual exception handling.
C++ allows for pointer arithmetic while Java does not.
Java has a larger standard library than C++.
C++ is o...read more
Q229. Why we use @transiant annotations in spring
We use @transient annotations in Spring to mark fields that should not be persisted.
The @transient annotation is used to exclude a field from being persisted to the database.
It is commonly used for fields that are derived from other fields or are not relevant to the persistence layer.
The @transient annotation is also used to prevent serialization of certain fields in distributed systems.
It is important to note that @transient fields will not be persisted or serialized, so the...read more
Q230. tell me about java8 features
Java 8 introduced several new features including lambda expressions, streams, functional interfaces, and default methods.
Lambda expressions allow you to write more concise code by enabling functional programming.
Streams provide a way to work with sequences of elements and perform operations on them in a declarative way.
Functional interfaces are interfaces with a single abstract method, which can be implemented using lambda expressions.
Default methods allow interfaces to have ...read more
Q231. What is Java Python
Java and Python are both popular programming languages used for various applications.
Java is a statically typed language known for its platform independence and object-oriented programming features.
Python is a dynamically typed language known for its simplicity and readability, often used for web development, data analysis, and artificial intelligence.
Both languages have large communities and extensive libraries for different purposes.
Java example: public class HelloWorld { p...read more
Q232. how to remove autoconfiguration in springboot
To remove autoconfiguration in Spring Boot, exclude the specific autoconfiguration class from the application.
Exclude the autoconfiguration class using @EnableAutoConfiguration annotation with exclude attribute
Create a configuration class and exclude the specific autoconfiguration class using @EnableAutoConfiguration annotation
Use application.properties or application.yml to exclude autoconfiguration classes
Q233. why js used not java
JavaScript is used for front-end web development due to its ability to create interactive and dynamic user interfaces.
JavaScript is specifically designed for client-side scripting in web development.
Java is a backend language and is not typically used for front-end development.
JavaScript allows for dynamic content updates without reloading the entire page.
JavaScript is supported by all major web browsers, making it a versatile choice for web development.
Q234. What is Java?What are its features
Java is a high-level programming language known for its platform independence and object-oriented features.
Java is platform-independent, meaning it can run on any device with a Java Virtual Machine (JVM)
It is object-oriented, allowing for modular and reusable code
Java has automatic memory management through garbage collection
It supports multithreading for concurrent programming
Java has a rich set of APIs and libraries for various functionalities
Q235. What archive is present in EAR?
EAR file contains a JAR file which is an archive of Java classes, resources, and metadata.
EAR file stands for Enterprise Archive
Contains one or more Java EE modules (WAR, JAR, etc.)
Used for packaging and deploying enterprise applications
Q236. Create package and call tha class in anotherclassby using object on oops
Create a package in Java and call a class from that package in another class using object-oriented programming principles.
Create a package by using the 'package' keyword at the beginning of the Java file.
Define a class within the package and create an object of that class in another class.
Import the package in the class where you want to use the class from the package.
Access the class from the package using the object created in the other class.
Q237. What is default package
Default package is a package that does not have any name.
Default package is also known as unnamed package.
Classes in default package can be accessed from other classes in the same package but not from other packages.
It is not recommended to use default package in production code.
Example: package myPackage; // named package, package // default package
Q238. What is c language, what is java
C language is a procedural programming language, while Java is an object-oriented programming language.
C language is low-level and provides direct access to memory, making it efficient for system programming.
Java is platform-independent and has a rich set of libraries, making it suitable for developing applications.
C language uses pointers extensively, while Java handles memory management automatically with garbage collection.
C language is widely used for operating systems, e...read more
Q239. How is Java advantageous than C++?
Java is advantageous than C++ due to its platform independence and automatic memory management.
Java is platform independent while C++ is platform dependent
Java has automatic memory management while C++ requires manual memory management
Java has a simpler syntax compared to C++
Java has a larger standard library compared to C++
Java has better support for multithreading compared to C++
Q240. what difference between @EnableAutoConfiguration and ComponentScan
EnableAutoConfiguration enables auto-configuration of Spring Boot application while ComponentScan scans for Spring components.
EnableAutoConfiguration automatically configures Spring Boot application based on classpath and other settings.
ComponentScan scans for Spring components and registers them as beans.
EnableAutoConfiguration is used in main application class while ComponentScan can be used in any configuration class.
EnableAutoConfiguration can be disabled using @SpringBoo...read more
Q241. Describe Java8 Features
Java8 introduced several new features including lambda expressions, functional interfaces, streams, and default methods.
Lambda expressions allow you to write code in a more concise and readable way.
Functional interfaces are interfaces with a single abstract method, which can be implemented using lambda expressions.
Streams provide a way to work with collections of objects in a functional style.
Default methods allow interfaces to have methods with implementations.
Other features...read more
Q242. Why do you prefer python to java?
Python is preferred over Java for software testing due to its simplicity, readability, and extensive testing libraries.
Python has a simpler syntax compared to Java, making it easier to write and read test scripts.
Python's extensive testing libraries like pytest and unittest provide powerful tools for test automation.
Python's dynamic typing allows for faster development and easier maintenance of test scripts.
Python's large community and active support make it easier to find so...read more
Q243. What annotations are included in @SpringbootApplication annotation
The @SpringBootApplication annotation includes @Configuration, @EnableAutoConfiguration, and @ComponentScan annotations.
Includes @Configuration annotation to specify that the class can be used by the Spring IoC container as a source of bean definitions.
Includes @EnableAutoConfiguration annotation to enable Spring Boot's auto-configuration feature.
Includes @ComponentScan annotation to specify the base packages to scan for components.
Q244. what is difference between java and java script
Java is a programming language used for building applications, while JavaScript is a scripting language primarily used for web development.
Java is a statically typed language, while JavaScript is dynamically typed.
Java is compiled and runs on the Java Virtual Machine (JVM), while JavaScript is interpreted by the browser.
Java is used for building standalone applications, server-side applications, and Android apps, while JavaScript is mainly used for client-side web development...read more
Q245. What is java and explain its features
Java is a high-level programming language known for its platform independence and object-oriented features.
Java is platform-independent, meaning it can run on any device with a Java Virtual Machine (JVM)
It is object-oriented, allowing for modular and reusable code
Java is known for its robust standard library, providing a wide range of pre-built functionality
It supports multithreading, allowing for concurrent execution of tasks
Java is statically typed, catching errors at compi...read more
Q246. Oop concept in java
OOP concept in Java refers to the principles of Object-Oriented Programming, such as encapsulation, inheritance, and polymorphism.
Encapsulation: Bundling data and methods that operate on the data into a single unit (object)
Inheritance: Allowing a class to inherit properties and behavior from another class
Polymorphism: Ability for objects of different classes to respond to the same method call
Q247. What is c code in java
C code in Java refers to the use of the Java Native Interface (JNI) to incorporate C code into Java programs.
C code in Java is typically used when performance optimization or low-level system access is required.
JNI allows Java programs to call C functions and use C libraries.
C code can be written separately and compiled into a shared library, which is then loaded and used by Java code.
JNI provides a way to pass data between Java and C, handle exceptions, and manage memory.
Exa...read more
Q248. What is the different between java and c
Java and C are both programming languages, but differ in syntax, usage, and platform compatibility.
Java is an object-oriented language, while C is a procedural language.
Java is platform-independent, while C is platform-dependent.
Java has automatic memory management, while C requires manual memory management.
Java has a larger standard library than C.
C is faster and more efficient than Java for certain tasks, such as system programming.
Java is commonly used for web development,...read more
Q249. difference b/w java and c++
Java is platform-independent, object-oriented, and uses automatic memory management, while C++ is platform-dependent, supports multiple paradigms, and requires manual memory management.
Java is platform-independent, while C++ is platform-dependent.
Java is object-oriented, while C++ supports multiple paradigms.
Java uses automatic memory management (garbage collection), while C++ requires manual memory management.
Java has a simpler syntax compared to C++.
Java has a larger standa...read more
Q250. 2. What is autowired
Autowired is a feature in Spring Framework that allows automatic dependency injection.
Autowired annotation is used to automatically wire beans by type.
It eliminates the need for explicit bean configuration in XML or Java configuration.
Autowired can be used on properties, setters, and constructors.
Example: @Autowired private UserService userService;
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