Java 8 Interview Questions Preparation Course


Java 8 is one of the major releases from Java with features like Streams, Lambdas etc. A lot of companies are looking for software developers proficient in Java 8 features.

This course contains basic to expert level Java 8 interview questions that an interviewer asks. Each question is accompanied with an answer so that you can prepare for job interview in short time.

We have compiled this course after attending dozens of technical interviews in top-notch companies like- Google, Netflix, Amazon etc.

Often, these questions and concepts are used in our daily programming work. But these are most helpful when an Interviewer is trying to test your deep knowledge of Java 8 features.

Join the course for just $10!!

What is the biggest benefit of this course to me?

Finally, the biggest benefit of this course is that you will be able to demand higher salary in your next job interview.

It is good to learn Java 8 for theoretical benefits. But if you do not know how to handle interview questions on Java 8, you can not convert your Java 8 knowledge into higher salary.

What are the topics covered in this course?

We cover a wide range of topics in this course. We have questions on Java 8 best practices, Security, Pact, Bulkhead Design Pattern etc.

How will this course help me?

By attending this course, you do not have to spend time searching the Internet for Java 8 interview questions. We have already compiled the list of the most popular and the latest Java 8 Interview questions.

Are there answers in this course?

Yes, in this course each question is followed by an answer. So you can save time in interview preparation.

What is the best way of viewing this course?

You have to just watch the course from beginning to end. Once you go through all the videos, try to answer the questions in your own words. Also mark the questions that you could not answer by yourself. Then, in second pass go through only the difficult questions. After going through this course 2-3 times, you will be well prepared to face a technical interview in Java 8 topic.

What is the level of questions in this course?

This course contains questions that are good for a Fresher to an Architect level. The difficulty level of question varies in the course from a Fresher to an Experienced professional.

What are the sample questions covered in this course?

Sample questions covered in this course are as follows:

  1. What are the new features released in Java 8?
  2. What are the main benefits of new features introduced in Java 8?
  3. What is a Lambda expression in Java 8?
  4. What are the three main parts of a Lambda expression in Java?
  5. What is the data type of a Lambda expression?
  6. What is the meaning of following lambda expression?
  7. Why did Oracle release a new version of Java like Java 8?
  8. What are the advantages of a lambda expression?
  9. What is a Functional interface in Java 8?
  10. What is a Single Abstract Method (SAM) interface in Java 8?
  11. How can we define a Functional interface in Java 8?
  12. Why do we need Functional interface in Java?
  13. Is it mandatory to use @FunctionalInterface annotation to define a Functional interface in Java 8?
  14. What are the differences between Collection and Stream API in Java 8?
  15. What are the main uses of Stream API in Java 8?
  16. What are the differences between Intermediate and Terminal Operations in Java 8 Streams?
  17. What is a Spliterator in Java 8?
  18. What are the differences between Iterator and Spliterator in Java 8?
  19. What is Type Inference in Java 8?
  20. Does Java 7 support Type Inference?
  21. How does Internal Iteration work in Java 8?
  22. What are the main differences between Internal and External Iterator?
  23. What are the main advantages of Internal Iterator over External Iterator in Java 8?
  24. What are the applications in which we should use Internal Iteration?
  25. What is the main disadvantage of Internal Iteration over External Iteration?
  26. Can we provide implementation of a method in a Java Interface?
  27. What is a Default Method in an Interface?
  28. Why do we need Default method in a Java 8 Interface?
  29. What is the purpose of a Static method in an Interface in Java 8?
  30. What are the core ideas behind the Date/Time API of Java 8?
  31. What are the advantages of new Date and Time API in Java 8 over old Date API?
  32. What are the main differences between legacy Date/Time API in Java and Date/Time API of Java 8?
  33. How can we get duration between two dates or time in Java 8?
  34. What is the new method family introduced in Java 8 for processing of Arrays on multi core machines?
  35. How does Java 8 solve Diamond problem of Multiple Inheritance?
  36. What are the differences between Predicate, Supplier and Consumer in Java 8?
  37. Is it possible to have default method definition in an interface without marking it with default keyword?
  38. Can we create a class that implements two Interfaces with default methods of same name and signature?
  39. How Java 8 supports Multiple Inheritance?
  40. Can we access a static method of an interface by using reference of the interface?
  41. How can you get the name of Parameter in Java by using reflection?
  42. What is Optional in Java 8?
  43. What are the uses of Optional?
  44. Which method in Optional provides the fallback mechanism in case of null value?
  45. How can we get current time by using Date/Time API of Java 8?
  46. Is it possible to define a static method in an Interface?
  47. How can we analyze the dependencies in Java classes and packages?
  48. What are the new JVM arguments introduced by Java 8?
  49. What are the popular annotations introduced in Java 8?
  50. What is a StringJoiner in Java 8?
  51. What is the type of a Lambda expression in Java 8?
  52. What is the target type of a lambda expression ?
  53. What are the main differences between an interface with default method and an abstract class in Java 8?

What are the requirements?

  1. Some Software Development Experience
  2. Familiar with basic Java

What am I going to get from this course?

  • Learn important concepts of Java 8
  • Understand Java 8 features
  • Answer interview questions on Java 8
  • Demand higher salary or promotion based on the knowledge gained

What is the target audience?

  • Software Engineer, Sr. Software Engineer, Member Technical Staff, Expert
  • DevOps Engineer, Operations Engineer
  • Software Architect, Development Manager, Director
  • Anyone who wants to learn Java 8 features

Join the course for just $10!!

What is the target type of a lambda expression ?

The target type of a lambda expression represents a type to which the expression can be converted.

The target type for a lambda expression is a functional interface.

The lambda expression must have same parameter type as the parameter in the function of the interface. It must also return a type compatible with the return type of function.

What are the main differences between an interface with default method and an abstract class in Java 8?

An interface with a default method appears same as an Abstract class in Java. But there are subtle differences between two.

  • Instance variable: An interface cannot have instance variables. An abstract class can have instance variables.
  • Constructor: An interface cannot have a constructor. An abstract class can have constructor.
  • Concrete Method: An interface cannot have concrete methods other than default method. An abstract class is allowed to define concrete methods with implementation.
  • Lambda: An interface with exactly one default method can be used for lambda expression. An abstract class cannot be used for lambda expression.

What is a StringJoiner in Java 8?

StringJoiner is a new class in Java 8 that can be used to create a String. It can construct a sequence of characters separated by a delimiter. It can also optionally add a prefix and suffix to this sequence. We can use this sequence to get a String.

E.g.
The String “[One:Two:Three]” may be constructed as follows:

StringJoiner sj = new StringJoiner(“:”, “[“, “]”);
sj.add(“One”).add(“Two”).add(“Three”);
String desiredString = sj.toString();

What is the type of a Lambda expression in Java 8?

The type of a lambda expression depends on the context it is being used.

A lambda is like a method reference. It does not have a type of its own.

Generally, a Lambda is an instance of a Functional Interface.

What are the popular annotations introduced in Java 8?

Some of the popular annotations introduced in Java 8 are:

  • @FunctionalInterface: This annotation is used to mark an interface as Functional Interface. As mentioned earlier, A FunctionalInterface can be used for lambda expressions.
  • @Repeatable: This annotation is used for marking another annotation. It indicates that the marked annotation can be applied multiple times on a type.

How can we get current time by using Date/Time API of Java 8?

In Java 8 we can use Clock class to get the current time. Instead of using old method System.currentTimeMillis(), we can create a Clock object and call millis() method to get the current time in milliseconds.

We can also call instant() method on Clock object to get the current time in a readable format.

How can we analyze the dependencies in Java classes and packages?

Java 8 comes with a new command line tool jdeps that can help in analyzing the package-level and class-level dependencies.

We can pass a jar file name or a class name as an argument to this tool. It will list all the dependencies of that jar or class.

What are the new JVM arguments introduced by Java 8?

In Java 8, PermGen space of ClassLoader is removed. It has been replaced with MetaSpace.

Now we can set the initial and maximum size of MetaSpace.

The JVM options -XX:PermSize and –XX:MaxPermSize are replaced by -XX:MetaSpaceSize and -XX:MaxMetaspaceSize respectively in Java 8.