To land the job, it helps to review common and challenging Java interview questions. The object-oriented, class-based programming language is one of the most popular programming languages in the world, after all.
We prepared these Java interview questions with answers from experts. You can expect to learn the basics with topics that are easy for beginners as well as more difficult problems with specific code to help professional software developers and Android app developers.
Remember that the programming language is liked by both experienced programmers and people who are new to the field because it has many useful features. Our interview questions start with basic Java concepts and progress to much more difficult challenges.
If you’re looking for a new job or want to hire more people, keep reading for the best Java interview questions for 2024.
These basic Java interview questions and Java programming interview questions will help you get ready for your interview. Review the answers, including the coding examples, and put your best foot forward.
Please keep in mind that we also gave you a PDF to help you study, which you can download and use to learn on the go:
If you would rather watch videos whenever you want, this course will help you read more and get ready for a Java-based interview: Java Interview Guides: 200 Interview Question and Answer
If not, this book, Elements of Programming Interviews in Java: The Insider Guide second edition, will help you do well in your next Java interviews.
NetBeans is one of the most popular integrated development environments (IDEs) for Java developers. It provides a comprehensive set of tools for Java, from coding and debugging to testing and profiling. With powerful code completion, refactoring tools, and integration with popular application servers, NetBeans makes Java development faster and easier.
If you have an upcoming Java or NetBeans interview, you’ll want to be prepared to answer questions about NetBeans and demonstrate your skills. Here are some of the top NetBeans interview questions and answers to help you get ready:
1. What is NetBeans? What are some of its key features?
NetBeans is a free, open source IDE primarily used for Java development. Some of its key features include:
- Smart code completion, suggestion, and documentation
- Drag-and-drop GUI builder
- Integrated debugging and profiling
- Support for Maven and Ant build tools
- Integration with version control systems like Git and Subversion
- Plugins for Spring, Hibernate, Java EE, PHP, C/C++, and more
- Extensible via plugins
2. What are some benefits of using NetBeans over other Java IDEs?
Some benefits of NetBeans include:
- It’s free and open source
- Great GUI builder for Swing and JavaFX
- Seamless Maven integration
- Large library of plugins
- Integrated tools for Tomcat, GlassFish, etc
- Lightweight and fast
- Powerful code refactoring features
3. Explain the NetBeans project/application structure.
A NetBeans project contains logical groups of related files called source folders. Some common folders are
src– contains Java source fileslib– contains compiled JAR librariestest– contains test case source filesdocs– contains documentationconf– contains XML configuration files
The nbproject folder contains NetBeans project metadata and build scripts.
4. How do you create a new project in NetBeans?
To create a new project in NetBeans
- Click File > New Project
- Select Java category and project type e.g. Java Application
- Enter project name and location
- Select project settings like Java version, build tool, etc
- Click Finish
This creates the new project with the standard folders and files
5. Explain the NetBeans GUI designer. How do you use it?
The NetBeans GUI designer lets you quickly build Java Swing interfaces by dragging and dropping components onto a canvas. You can then view the generated code, make adjustments, and attach event handlers without editing code manually.
To use it:
- Right-click on a file and select New > JFrame Form
- Drag components from the Palette onto the canvas
- Use the Properties pane to customize the UI components
- View/edit the code in the Source tab
- Double-click on components to attach event handlers
6. How do you run a Java application in NetBeans?
There are several ways to run a Java application in NetBeans:
- Right-click on the project and select Run
- Click the Run Project icon in the toolbar
- Navigate to the main class, right-click and select Run File
- Use keyboard shortcut Shift + F6
- From the Run menu, select Run Project/File
The output displays in the Output window at the bottom.
7. Explain the debugger features in NetBeans.
NetBeans provides an excellent visual debugger with standard features like:
- Breakpoints
- Step over, step into and step out
- Variable inspection
- Call stack
- Debugging windows like Local Variables, Watches, etc.
Additional features include:
- Live expression evaluation
- Multiple sessions
- Taking thread snapshots
- Attaching to running processes
8. How do you set a breakpoint in NetBeans?
To set a breakpoint in NetBeans:
- Open the Java file
- Click on the line number margin to add a breakpoint
- A red dot appears indicating the breakpoint
You can also:
- Right-click on a line and select Breakpoint > Toggle
- Press Ctrl + F8
- Use the Breakpoints window
9. What build tools does NetBeans support?
NetBeans has built-in support for Apache Ant and Maven. You can create new projects using either build tool.
For Ant, NetBeans generates the necessary build script (build.xml) with targets for compiling, building JARs, etc.
For Maven, NetBeans handles dependency management and syncs with the project object model (POM.xml). You can run Maven goals like clean, install, etc. directly within NetBeans.
10. How do you connect a database in NetBeans?
To connect to a database in NetBeans:
- Right-click on the Services tab and select New Connection
- Select the database type e.g. MySQL, Oracle, etc.
- Enter the database connection details like URL, username, password
- Test and verify the connection
- Click Next and complete the wizard to create the connection
The database connection will now show under the Services tab. You can expand it to see database objects like tables, views, stored procedures, etc.
11. Explain refactoring in NetBeans.
Refactoring is the process of restructuring code without changing external behavior. NetBeans provides automated refactoring tools to safely rename identifiers, change method parameters, extract code into methods, and more.
To refactor code:
- Select the item to refactor
- Right-click and select Refactor
- Choose the refactor action e.g. Rename
- Preview changes in the Refactoring window
- Click Do Refactor to apply changes
This automates modifying all occurrences and updating references safely.
12. How do you configure Tomcat server in NetBeans?
To configure Tomcat in NetBeans:
- Click Tools > Servers
- Click Add Server and select Apache Tomcat
- Set Tomcat installation directory
- On the next page, update settings like port, username/password, etc.
- Click Finish
Tomcat will now show under the Services tab. Right-click on it to start, stop, deploy to, and configure.
13. Explain the Java EE workflow in NetBeans.
NetBeans provides seamless support for end-to-end Java EE development:
- Create EJB, web service, web application, etc. project from templates
- Develop using annotated POJOs, JSF, JPA, EJBs, etc.
- Package as WAR/EAR file with Ant/Maven
- Deploy project on integrated Java EE server like GlassFish, Tomcat, etc.
- Manage database connections
- Develop, deploy and test without leaving the IDE
This improves productivity for enterprise Java development.
14. How do you debug a remote Java application in NetBeans?
To debug remotely:
- Click Debug > Attach Debugger
- Select Remote from the Debugger drop-down
- Enter remote debug settings like host, port, username, etc.
- Click Attach
- Debug as if it were local
You can also open project properties and set “Run Configuration” to remote.
15. What are some useful NetBeans plugins?
Some useful NetBeans plugins include:
- SonarLint – code quality and bug detection
- Git – Integrated Git tools
- NBProfiler – application profiling
- Chrome Debugger – debug JavaScript in Chrome
- Gradle – build automation
- PlantUML – diagramming plugin
- NetBeans Java Hint – code suggestions
16. How is NetBeans licensed? What is the current version?
NetBeans is licensed under Apache 2.0. It’s owned by the NetBeans community and supported by Oracle.
The latest stable release as of 2022 is NetBeans 14. New major versions are released every 1-2 years.
17. What platforms and languages does NetBeans support?
NetBeans supports Java, JavaScript, PHP, Groovy, C/C++, and more on Windows, macOS, Linux, and Solaris. Plugin support expands the languages and platforms further.
The Java support is the most comprehensive, but NetBeans works well for web development using HTML5, JavaScript, CSS, and PHP.
18. How do you find documentation and get help in NetBeans?
NetBeans provides several ways to access documentation and help:
- Hover over any item and press Ctrl + Q for quick documentation
- Select Help > Help Contents to open NetBeans documentation
- Go to Help > Support to get community support and find resources
- Use keyboard shortcut Ctrl + Shift + F1 to view context help
19. Explain NetBeans Platform. How is it used?
NetBeans Platform is a framework for building cross-platform desktop applications using Swing components. It provides:
- Modular architecture
- Lifecycle management
Arrays, Strings and Vectors Java Interview Questions
An array needs to be declared with a size, but an array list doesn’t need to be declared with a size because its size changes on the fly. To put an object into an array, there is the need to specify the index. However, no such requirement is in place for an array list. While an array list is parameterized, an array is not parameterized.
String variables are stored in a constant string pool. With the change in the string reference, it becomes impossible to delete the old value. Say a string has a value called “Old.” Adding the new value “New” will not get rid of the old value. It will still be there, however, in a dormant state. In a Stringbuffer, values are stored in a stack. With the change in the string reference, the new value replaces the older value. The StringBuilder, which is also a Stringbuffer but is not synchronized, is faster than the Stringbuffer even though both are synchronized and therefore safe for multiple threads. Hence, performance is faster in Stringbuilder than the Stringbuffer.
The string pool is a collection of strings stored in the heap memory refers to. Whenever a new object is created, it is checked if it is already present in the string pool. If it’s already there, the same reference is sent back to the variable. If it’s not, a new object is made in the string pool and the reference to that object is sent back.
Packages Java Interview Questions
Packages are Javas way of grouping a variety of classes and/or interfaces together. The functionality of the objects decides how they are grouped. Packagers act as “containers” for classes.
Enlisted below are the advantages of Packages:
- Classes of other programs can be reused.
- There can be two classes with the same name in two different packages.
- Classes can be hidden by packages, which means that only internal programs and classes can be used.
- They also separate design from coding.
Top Core Java Interview Questions || Core Java Interview Questions and Answers [MOST ASKED]
FAQ
What is JDK in Java interview questions?
What is JVM in Java interview questions?
What are Java interview questions?
These Java interview questions are based-on Core and advanced Java programming topics such as Core Java Concepts, Object-Oriented Programming (OOP), Java Collections Framework, Multithreading, Java I/O, Exception Handling, Java Memory Management, Java Annotations, Java Design Patterns, Java Streams API, JDBC, and many more.
What is NetBeans in Java?
All You Need To Know About Net NetBeans is an open-source IDE used for developers for developing Java desktop applications. Netbeans provides the Java developers all the tools needed to create professional desktop, mobile and enterprise applications. In this article, we will cover the following topics about Netbeans in Java:
What questions do recruiters ask during a Java interview?
As the interview progresses, the recruiter may ask questions to get to know your unique Java experience. Understanding your relevant experience and background can help recruiters determine if you’re able to perform the job’s duties. Here are some questions an interviewer may ask to evaluate your experience and background with Java:
How do I prepare for a Java interview?
To have a successful interview, it helps to review common Java interview questions. Knowing the questions an interviewer may ask can help you prepare answers that effectively highlight your skill level and experience with this high-level programming language.
