Java 8 Features⌗

  1. Functional Interfaces
  2. Methods
  3. Streams
  4. Date and Time

Why Java 8 is Important?⌗

  • java 8 improves overall application performance with little work.
  • Lambda Expressions, Stream API, new methods added to existing classes improve productivity.
  • Java 8 Optional type gives developers flexibility when dealing with null values, reducing the likelihood of NullPointerExceptions.
  • Less Code: Java 8 reduces boilerplate with a functional style, focusing on what to do, not how.
  • Parallel Friendly: With simple APIs, the JVM splits tasks and runs them across cores using fork/join.

Reactive Programming⌗

  • It’s a design pattern that focuses on use of asynchronous and non-blocking data streams to handle data and events.

Need of Reactive Programming⌗

  • For Efficiency and Scalability.

Without Reactive Programming⌗

Image Description \ Thread will be blocked until Operation is done.

With Reactive Programming⌗

Image Description Thread don’t wait for Response.

Functional Interface⌗

A functional interface in Java is an interface that contains exactly one abstract method. It can have any number of default or static methods, but only one abstract method.

Lambda Expressions⌗

A lambda expression is a concise way to represent an anonymous function—a function without a name—in Java. Introduced in Java 8.

Comparable<> Interface⌗

The Comparable<T> interface is used to define the natural ordering of objects. It allows a class to compare its instances using the compareTo() method.

✅ Syntax Example:⌗ 

class Student implements Comparable<Student> {     
	int rollNo;
	public int compareTo(Student other) {
		return this.rollNo - other.rollNo;
	} 
}

✅ What does this mean in compareTo()?⌗

  • this → current object (e.g., s1)

  • other → object passed for comparison (e.g., s2)

  • this.rollNo - other.rollNo:

    • Negative → this comes before

    • Zero → equal

    • Positive → this comes after

✅ What does Collections.sort(students) do?⌗

  • Sorts the list using the logic in compareTo().

  • Internally calls:

    java

    CopyEdit

    s1.compareTo(s2)

    for every pair of objects.

✅ When to use Comparable?⌗

  • When the class should define its own default sorting rule (e.g., by roll number, name, etc.).

  • Works automatically with Collections.sort() or Arrays.sort().