Top 21 Groovy Interview Questions with Answers for Java developers

Hello guys, if you are preparing for Groovy Developer interview or a Java Developer interview where Groovy is mentioned as required skill then you should prepare for it. If you are looking for common Groovy Interview questions and their answers then you have come to the right place. Earlier, I have shared best Groovy books and online courses to learn Groovy and in this article article, I am going to share frequently asked Groovy Interview Questions with answers.  These Groovy questions covers essential features of Groovy programming language and suitable for both beginners and programmers with 1 to 3 years of experience. 

If you have worked in Groovy then you can easily answer these questions but if you struggle then you can always check these best Groovy courses to revise essential Groovy concepts. 

By the way, this is indeed your day because you have just found the right thing that will help you realize success in your upcoming Groovy interview. Do not panic anymore because everything is on the right track and you will see success on that interview day. 

20 Groovy Interview Questions and Answers

Without wasting anymore of your time, here is a list of 20 Groovy questions and answers. The list covers basic Groovy concepts like how Groovy complements Java, what are traits in Groovy and clean, clear, and concise syntax of Groovy. You can go through these questions to quickly revise essential Groovy concepts.  The top 20 Groovy interview questions that are going to make everything easy for you are as follows:

1. What is Groovy?
Answer: Groovy is an object-oriented programming language for JVM (Java Virtual Machines). It is used to combine Java modules, to write Java application and to extend existing Java application.

2. What is the limitation of Groovy?
Answer:

• Groovy can be slower
• Groovy might need lots of memory
• Groovy start up time requires improvement
• It requires Java knowledge
• It takes sometimes to get use to like New Syntax, closures, default typing,
• Documentation is thin

3. What is the role of Grape dependency in Groovy?
Answer: Grape is a JAR dependency manager included into Groovy. It allows you to add quickly maven repository dependencies to your classpath, making scripting easier. The simplest use is adding an annotation to your script.

4. What is the scope of a variable?
Answer: The scope of a variable means the part of a program where the particular variable can be accessed. In the Go language, every variable is statistically scoped that means the scope of a variable is declared at compile time itself. Scope of a variable in the Go language is categorized into two types

• Local variables these variables are either declared inside a function or a block
• Global variables these variables are declared outside the function or a block

5. Is there any limit on appending the jars that are available in the Groovy?
Answer: No, there is no such limit. Programmers can make them available in any number whenever they need them.

6. What is the significance of ExpandoMeta class in Groovy?
Answer: It is a powerful option available in the Groovy. Through this class, it is possible for the programmers to consider and add properties, constructors, methods, and operations to the task. By default, it cannot be inherited and users need to call it whenever they need it. The command for this is “ExpandoMetaClass.enabledglobally()”

7. What is Querying in Groovy? Why there is a need for it?
Answer: Querying is basically an approach to detect whether the set of commands is compatible with the operations or not. Also, it can be considered when users need to verify or cross-examine something. The Groovy is an approach that has support for the various queries and the same can be handled. Its prime task is to make sure error-free outcomes in every situation.

8. What does the AST abbreviate for?
Answer: It stands for Abstract syntax Tress.

9. Where can Groovy Bitwise Operators implement?
Answer: Bitwise operators can implement on INT and on a BYTE. There is a total of four bitwise operators that are helpful in this manner.

10. Is it possible for you to integrate with other applications that are not based on Java?
Answer: Yes, this is possible. However, only one problem with Groovy integration is that it offers limited features that cannot be used to handle complex programming.

11. Compare the old version of the Groovy with the new version?
Answer: When it comes to the new version, there are a lot of advanced features that are quite simple to use when compared to the older version. With the help of the new version, it is also possible to stream arrays and objects of object-oriented methods used in the older version. In addition to this, a lot of run time errors have been eliminated at various stages and commands also have been improved for smooth operations.

12. What are different kinds of objects in Groovy?
Answer: There are three different kinds of objects in groovy:

• POJO
• POGO
• Groovy Interceptors

13. What is delegation in Groovy?
Answer: Delegation is when a class has methods that directly call methods of another class with same signature.

14. What is Trait in Groovy?
Answer: Traits in groovy are like interfaces with default implementation and state.

15. What is Closure in Groovy?
Answer: A closure in Groovy is an open, anonymous, block of code that can take arguments, return a value and be assigned to a variable.

16. What are the different flavors of String available in Groovy?
Answer: There are two flavors of String available in Groovy:

• Plain String
• GStrings

17. What are the important characteristics of Mixins?
Answer: Below are a few of the important characteristics of Mixins:

• Mixins are visible on all threads.
• There are no restrictions on what method to mix in.
• We can mix into superclasses and interfaces.
• A mixin can override a method of a previous mixin but not methods in the metaclass.
• There is no per-instance mixin.
• A Mixin cannot easily be undone.

18. Mention important features that Groovy JDK offers.
Answer: Some of the important features offered by groovy JDK are provided as follows:

• Collection of literals: -The literal syntax and its initialization are easy and readable I Groovy, whereas in Java, these are difficult and cumbersome.
• Groovy Beans property: – Java lacks direct syntactic support even though it is based on JavaBeans’ concept for structure. In Groovy, a field can be declared as a property or as trivial, and it can access the same too.
• This feature was presented in groovy from the beginning. It was there in its collection framework.
• JDK enhancements: – Many operators and classes and additional methods have also been introduced by the latest versions of Groovy.

19. What is JVM?
Answer: It stands for Java Virtual Machines. They are basically regarded as one of the essential components or requirements on which Groovy works. In fact, Groovy is largely based on these machines. This is due to the fact that Groovy needs a Java-based platform to perform its task smoothly and reliably.

20. Is there any limit on appending the jars that are available in the Groovy?
Answer: No, there is no such limit. Programmers can make them available in any number whenever they need them.

21. What is difference between Groovy and Java? (answer)

While both Java and Groovy code are compiled into byte code there are many difference between Groovy and Java, particularly on syntax. For example, Groovy support collection literals which are still not supported by Java. Groovy also supports multi-line string which are not supported until Java 13 when Text block was introduced. 

That's all about frequently asked Groovy Interview Questions with answers for 1 to 3 years of experienced professionals. You should now know that these are the kind of questions you will face in your interview and therefore you should pay keen attention to them. Just make sure that you have mastered them and also have confidence in yourself and everything will fall in the right place.

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Thanks for reading this article so far. All the best for your Java and Groovy Developer interviews and if you have any questions which don't know answer or any doubt feel free to ask in comments. 

P. S. - If you are new to Groovy programming and want to learn Groovy programming language in depth, then I highly recommend you check out these best Groovy Courses for beginners, which are both comprehensive and very engaging. You can use this course to learn Groovy for both scripting as well as writing object oriented code.