Java 8

Practice 40 Java 8 interview questions with detailed answers. Part of the Java 8 track on Java Interview Hub.

• What are the new features introduced in Java 8?
• What is a lambda expression in Java 8, and what are its benefits?
• What is the difference between a Lambda Expression and an Anonymous Inner Class?
• What is a Functional Interface in Java 8?
• What are some of the predefined functional interfaces in Java 8?
• What is the Streams API in Java 8? How does it work?
• Explain the difference between map() and flatMap() in Streams.
• How can you filter a collection using Streams in Java 8?
• What are Default Methods in Java 8, and why were they introduced?
• How are Static Methods in interfaces different from Default Methods in Java 8?
• What is Optional in Java 8, and how is it used?
• How do you handle null values in Java 8 using Optional?
• What is the difference between findFirst() and findAny() in Streams?
• Explain the purpose of the Collectors class in Java 8.
• What is the significance of the forEach() method in Java 8?
• How does Java 8 handle parallel processing with the Streams API?
• What is the purpose of the Predicate functional interface in Java 8?
• How do you create an infinite stream in Java 8?
• What is the Function interface in Java 8, and how is it used?
• What are method references in Java 8, and how do they relate to Lambda Expressions?
• How can you sort a collection using Streams in Java 8?
• What is the use of reduce() in Java 8 Streams?
• How does the filter() method work in Java 8?
• What is the significance of Collectors.toList() in Java 8 Streams?
• Can you explain how Stream.of() works in Java 8?
• How is Java 8 backward-compatible with earlier versions of Java?
• What is the difference between limit() and skip() in Java 8 Streams?
• Explain how to convert a list to a map using Streams in Java 8.
• What is the difference between Stream.iterate() and Stream.generate()?
• How can you apply a custom comparator in a stream pipeline in Java 8?
• Can you explain why Java 8 introduced the concept of Default Methods in interfaces, and what problem does it solve?
• Is it possible to use this and super in a Lambda expression? Explain why or why not.
• How can a Lambda expression access variables outside its scope? What is the concept behind it?
• Can a Lambda expression throw an exception? How can you handle exceptions in a Lambda?
• What is the difference between Optional.of() and Optional.ofNullable()?
• How does the internal working of Stream.sorted() differ when using natural ordering versus custom comparator?
• Can you use Optional as a method parameter? Why should or shouldn’t you do this?
• What will happen if you try to modify a local variable inside a Lambda expression?
• Can you use the synchronized keyword inside a Lambda expression?
• What is the difference between count(), sum(), and reduce() in Java 8 Streams?