Interview Questions
Java
Java interview questions
Java Interview Questions
Java Interview Questions
java8
Java8 Examples
java8 interview questions
java8 streams examples
Java8 Streams Interview Questions
In this post, we will see Java8 Streams Interview questions.
What is the difference between a Stream and a Collection in Java 8
- Stream represents a sequence of elements and supports various operations to perform computations upon those elements. It is a more powerful and flexible version of the Enumeration and Iterator interfaces.
- A Collection represents a group of elements and supports various operations to add, remove, and retrieve elements. It is a more general interface that encompasses List, Set, and Queue interfaces.
- The main difference between a Stream and a Collection is that a Stream is designed for functional-style operations and Collection is designed for storage and retrieval of elements.
- A Stream is a one-time use object, it can be consumed once and it’s not possible to use it again. Streams are designed to perform operations on a large number of elements and they provide the advantage of lazy evaluation. This means that the operations are performed only when the terminal operation is called.
- Collections are designed for storage and retrieval of elements and they provide more general operations such as add, remove, and retrieve.
- You can convert a Collection to a Stream using the
stream()
method. In short, a Stream is a powerful and flexible way to perform functional-style operations on a sequence of elements, while a Collection is a more general interface for storing and retrieving elements.
List<String> words = Arrays.asList("Java", "Streams", "are", "powerful");
Stream<String> stream = words.stream();
How do you create a stream in Java 8
Please click on above post for more details: https://www.javasavvy.com/java8-streams-features-and-stream-creation-exampls/
How does the lazy evaluation feature of streams work?
Java 8 Streams Lazy Evaluation: Click here for more details
- Lazy evaluation means that a stream operation is not executed until it is absolutely necessary.
- This can lead to significant performance gains when working with large data sets.
- When you create a stream, it does not immediately process the data. Instead, it creates a “pipeline” of operations that will be performed on the data.
- The pipeline is not executed until a terminal operation is called on the stream.Please click on above link for more details
Can you explain the concept of a Intermediate and Terminal operations in Java 8 streams?
Can you provide an example of using the filter method on a stream?
In this below example, people are huge data set and finds out adult males
List<Person> people = new ArrayList<Person>();
Stream<Person> adults= people.stream()
.filter(p -> p.getAge() >= 18)
.filter(p -> p.getGender() == Gender.MALE);
Even Numbers
List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
Stream<Integer> evenNumbers = numbers.stream().filter(n -> n % 2 == 0);
can you provide example for map method to transform elements in a stream?
In this example, it will get the full name from the people’s list
List<Person> people = new ArrayList<Person>();
Stream<String> fullName = people.stream()
.map(p -> p.getFirstName() + " " + p.getLastName());