Java Functional Programming - Lambda & Stream Practice Tests

Learning is incomplete without challenging questions to assess the knowledge gained. There are courses and books available on Functional Programming & Stream API, which cover these topics in detail, but simply watching the video lectures or finishing the book will not give enough confidence unless the knowledge is validated.

Practice tests in this course will not only help you to assess your current knowledge of these topics but will also help you to revise the topics quickly. Questions are designed to challenge your understanding of the topics. Detailed explanations for all the questions are also provided for your reference.

Functional programming is not a new concept. Lambdas were implemented in other languages much before they were introduced in Java.

Before JDK 8, anonymous inner classes with a single method was the closest Java came to functional programming but with lots of boilerplate code. If anyone wants to really appreciate the implementation of lambda expressions in java, it is necessary to know the anonymous inner classes in depth and to understand anonymous inner class you need to have knowledge of Regular and method-local inner classes.

You may face lots of questions in interviews or written tests where you are asked to convert anonymous inner class syntax to lambda expression and vice versa. Therefore I decided to start with questions on inner classes and then go on with Lambda expression, method references, built-in functional interfaces and finally end this test series with questions on Stream API.