Java 9 Interview Questions and Answers
The most recent version of the Java programming language is Java 9. It has a lot of new features and enhancements and was released in September 2017. It’s crucial to be ready for inquiries regarding the new features if you’re searching for a job that requires Java 9. In this article, we go over some of the most typical Java 9 interview inquiries and offer advice on how to respond.
Java 9 Interview Questions and Answers
1. What is the difference between Java 9 and earlier versions of Java?
New improvements and functionality have been added to Java 9 version. JShell, Http2Client, the Java Platform Module System (JPMS), multi-release jar files, the Stack Walking API, private methods in interfaces, modifications to the Process and Collection APIs, improvements to the Stream API, and other components are included.
2. Can you explain what a module is in context with Java 9?
A module consists of a new module description file and a collection of resources and packages that are closely related. To put it another way, it’s an abstraction that enables us to make our code even more reusable.
3. What are some of the new features added to the Java programming language in Java 9?
Some of the new features added to Java 9 include:
– The Java Platform Module System
– A new HTTP Client API
– Improved Javadoc
– Multi-release JAR files
– The G1 Garbage Collector
– The Java Shell (JShell)
– The Process API
– Stream API Improvements
– Try-With-Resources Improvements
– Private Interface Methods
– Reactive Streams
– @SafeVarargs Annotation
- What is the purpose the implementation of JShell in Java 9?
An interactive tool for learning Java programming and creating Java code prototypes is the Java Shell tool (JShell). JShell is a Read-Evaluate-Print Loop (REPL), which instantly displays the results after evaluating declarations, statements, and expressions.
5. How do modules help reduce dependencies between packages?
Modules can be used in Java 9 to lessen package requirements. It is simpler to handle dependencies and prevent conflicts when a package’s exports and required modules are specified.
6. What is the main advantage of using Jigsaw over Maven or Gradle?
When working on large projects, Jigsaw’s more modular approach to Java programming can be a huge asset. You can divide your project into smaller, more manageable pieces using Jigsaw. Development and debugging may become easier and more effective as a result.
7. What does it mean when we say that a class is modularized?
When a class is divided into modules, it has been modularized. A Java application can make use of a module, which is a grouping of classes and other resources. We can increase the scalability and ease of maintenance of our apps by modularizing our code.
8. What’s the best way to isolate classes from external dependencies when developing applications?
Using a classloader is one method for separating classes from external dependencies when creating apps. By doing this, you’ll be able to load classes into your application without making them publicly visible.
9. How can you improve the security of an application without affecting its performance?
A few techniques exist for enhancing an application’s security without degrading its performance:
Use a security framework like the Java Security Framework, which is made to be quick and effective.
– Make use of the application server’s built-in security features, such as role-based access control and authentication.
– Apply security controls at the application level, such as output encoding and input validation.
10. How can you ensure that all references to a class are removed during garbage collection?
By setting a class’ static fields to null, you may make sure that all references to it are eliminated during garbage collection. All references to the class will be dropped as a result, and it will be unloaded.
11. What are the advantages of using JPMS over OSGi?
Over OSGi, JPMS offers a variety of benefits, such as a more modular approach, enhanced performance, and an easier development paradigm.
12. In your opinion, which one is better: Spring Boot or Java 9 Modules? Why?
Which is better—Spring Boot or Java 9 Modules—is not clearly definable. Both have benefits and drawbacks of their own. Java 9 Modules offer more flexibility and control, whereas Spring Boot is simpler to use and requires less configuration. The best choice ultimately depends on the requirements of the project.
13. What changes have been made to String handling in Java 9?
Compact Strings are once again an idea in Java 9. This means that anytime we build a String, a byte array will be utilised internally, with one byte being provided for each character, provided that all of the characters of the String can be represented using a byte—Latin-1 representation.
14. Can you explain the concept of try-with-resources blocks in Java?
A try statement that declares one or more resources is known as a try statement with resources. An object that needs to be closed after the programme is done using it is referred to as a resource. At the conclusion of the statement, each resource is closed thanks to the try -with-resources clause. any Java-implemented object.
15. What is the need to add “–add-modules ” option on java command line?
Javac and Java both have the —add-modules $modules option, which enables explicitly providing a comma-separated list of root modules in addition to the initial module. (By resolving their dependencies, root modules create the initial collection of modules from which the module graph is constructed.)
16. How can you use the $MODULE_PATH environment variable to specify modules path?
You can provide the path to a module by setting the $MODULE PATH environment variable to a list of directories that house module definitions.
17. What is the purpose of the –patch-module option?
Classes are added to a specified module with —patch-module. The indicated modules and their transitive dependencies are added to the module graph with the —add-modules option. One module reads another when —add-reads is used.
18. Can you give me some examples of how private methods can be used in interfaces in Java 9?
In Java 9, interfaces can employ private methods to increase their flexibility and modularity. For instance, input data may be verified by a private method before being processed by the remainder of the interface. This would eliminate the need to worry about the data validation phase while using the interface in various circumstances.
19. What are nested based access control (NBAC) rules?
A set of rules called the NBAC rules specify how Java 9 should handle nested classes and interfaces.
20. What is Project Portola?
Project Portola aims to support the Eclipse IDE with the new Java 9 Platform Module System.
- What are the main goals of Java 9?
Making the Java Standard Edition platform and JDK easier to navigate and scale down for small computing devices are the primary objectives of Java 9. Enhance overall security and sustain Java implementations as a whole, including the JDK. Permit enhanced application performance overall.
- What is the advantage of CompletableFuture in Java?
There are two primary advantages to this updated CompletableFuture: By calling the complete() method immediately, it can be expressly finished. Even if the computation didn’t finish, using default / intermediate results enables values of any kind to be available in the future.
- What is multi-resolution image api in Java 9?
A new multi-resolution picture API that enables numerous images with various resolution versions has been released with Java 9. This API enables the use of a collection of photos with various resolutions into a single multi-resolution image.
- What changes are made to Optional class in Java 9?
To help us deal with default values, Java 9 introduces three new methods to the Optional class: or(), ifPresentOrElse(), and stream().
- What changes are made to diamond operator in Java 9?
It can be combined with anonymous classes in Java 9 to streamline the code and increase readability.
- What changes are made to @Deprecated annotation in Java 9?
Two updates to the @Deprecated annotation are included in Java 9:
whetherElementIsSubjectToRemoval: Declares if the element being annotated is a candidate for removal in a later version. False is used as the default value.
since: The version in which the annotated element was declared deprecated is returned. Empty string is used as the default value.
- What is the use of of Nullable method in Stream?
If non-null, the ofNullable() method of the Stream class returns an empty stream; otherwise, it returns a sequential stream with one entry. This method was added to Java 9 to prevent NullPointerExceptions as well as stream null checks.
- What changes are there in iterate method of Stream?
A new input, a predicate that accepts the condition to halt the flow, has been added to the iterate() function of the Stream API in Java 9.
- What changes are made to Stream from java 8 in java 9?
While Java 9 provides an interactive REPL Jshell to explore API features and other new language features, Java 8 no longer supports the JDBC-ODBC bridge. Java 9 has collection factory methods that allow the components of collections or lists to be directly filled in place of Java 8’s removal of the PermGen memory capability.
- How can you check a system process details in Java 9?
The Java 9 Process API, which is in charge of managing and controlling operating system processes, has seen significant improvement. The native process ID, start time, accumulated CPU time, arguments, command, user, parent process, and offspring are now provided via the ProcessHandle Class.
In conclusion, this guide on Java 9 interview questions and answers provides a comprehensive resource for individuals preparing for Java 9 interviews. By exploring the various topics covered, including new features, modules, and enhancements, job seekers and interviewers can gain a deeper understanding of Java 9 and its capabilities. From the Java Platform Module System (JPMS) to improvements in the Streams API and process API, this guide equips individuals with the knowledge and insights necessary to excel in Java 9 interviews. Stay up-to-date with the latest Java advancements, enhance your programming skills, and confidently tackle Java 9-related questions with the help of this comprehensive resource.