10+ Java Programmer Interview Questions and Answers

Answering two technical questions related to Java programming.

• Double size refers to the number of bytes occupied by a double-precision floating-point value in Java, which is 8 bytes.

• The wrapper class of boolean is Boolean.

JVM is used to execute Java bytecode and provide platform independence.

• JVM stands for Java Virtual Machine.

• It interprets compiled Java code and executes it.

• JVM provides platform independence by converting bytecode to machine-specific code.

• JVM also manages memory allocation and garbage collection.

• Examples of JVM-based languages include Kotlin and Scala.

Inheritance is a mechanism in Java where a new class inherits properties and behaviors from an existing class.

• Allows for code reusability and promotes a hierarchical relationship between classes

• Derived class (subclass) inherits attributes and methods from a base class (superclass)

• Example: class Dog extends Animal, where Dog inherits properties and behaviors from Animal

Java Program is a set of instructions written in the Java programming language that can be executed by a computer.

• Java Program is a collection of classes and methods that define the behavior of a software application.

• It is written in the Java programming language and can be executed on any platform that has a Java Virtual Machine (JVM).

• Java Programs are compiled into bytecode, which is then interpreted and executed by the JVM.

• They can perform various tasks such as data manipu...read more

Java programming uses object-oriented programming principles and a robust set of libraries and frameworks.

• Java uses object-oriented programming principles such as encapsulation, inheritance, and polymorphism.

• Java has a rich set of libraries and frameworks for various purposes like GUI development, networking, database connectivity, etc.

• Java supports multithreading, exception handling, and dynamic memory allocation.

• Java programs are compiled into bytecode and run on the Java V...read more

An object is a fundamental concept in object-oriented programming, representing a real-world entity with its own state and behavior.

• An object is an instance of a class.

• It encapsulates data and methods.

• Objects can interact with each other through method calls.

• Example: A car object can have properties like color and speed, and methods like start() and stop().

A class is a blueprint for creating objects, while an object is an instance of a class.

• A class defines the properties and behaviors of objects.

• An object is a specific instance of a class.

• Classes can be used to create multiple objects with similar characteristics.

• Objects can interact with each other by calling methods defined in their class.

• Example: Class 'Car' defines properties like 'color' and behaviors like 'drive'. An object 'myCar' can be created from this class.

JRE stands for Java Runtime Environment.

• JRE is a software package that provides the necessary runtime environment for Java applications to run.

• It includes the Java Virtual Machine (JVM), class libraries, and other supporting files.

• JRE is required to run Java applications on a computer.

• Examples of Java applications that require JRE include Eclipse, NetBeans, and Minecraft.

To benefit the company, we can focus on improving efficiency, reducing costs, and increasing revenue.

• Streamline processes to reduce waste and increase productivity

• Implement cost-saving measures such as energy-efficient technology

• Explore new revenue streams through product diversification or expansion into new markets

There are 4 main OOPs concepts: Inheritance, Encapsulation, Polymorphism, and Abstraction.

• Inheritance allows a class to inherit properties and behavior from another class.

• Encapsulation restricts access to certain components within a class.

• Polymorphism allows objects to be treated as instances of their parent class.

• Abstraction hides complex implementation details and only shows the necessary features.

A servlet is a Java program that extends the capabilities of a server. It handles client requests and generates dynamic web content.

• Servlets are Java classes that are used to extend the capabilities of servers to handle requests and generate responses.

• Servlets are commonly used in web development to create dynamic web pages.

• Servlets follow the Java Servlet API, which provides a framework for writing servlets.

• Servlets can handle various types of requests such as GET, POST, PUT...read more

Pipeline is a series of connected processes that execute sequentially. Docker is a containerization platform.

• Pipeline is used for continuous integration and delivery.

• Docker allows developers to package their applications and dependencies into a container.

• Containers are lightweight and portable, making it easier to deploy applications across different environments.

• Docker uses a client-server architecture and can be managed through a command-line interface or a web-based dashbo...read more

Pipeline Docker is a tool that allows for continuous integration and deployment of Docker containers.

• Pipeline Docker automates the process of building, testing, and deploying Docker containers.

• It integrates with popular CI/CD tools like Jenkins and GitLab.

• Pipeline Docker uses a pipeline script to define the steps of the build process.

• It can be used to deploy containers to a variety of environments, including Kubernetes and AWS.

• Pipeline Docker can also be used to manage multip...read more

Java is a versatile programming language known for its platform independence, object-oriented approach, and robustness.

• Platform independence: Java programs can run on any platform that has a Java Virtual Machine (JVM)

• Object-oriented approach: Java supports the principles of encapsulation, inheritance, and polymorphism

• Robustness: Java has strong memory management, exception handling, and type safety features

• Rich API: Java provides a vast library of classes and interfaces for v...read more