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Java 8 Features

Theory

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Java 8 Features

8 Features is modern Java (5/8 toolkit). Lambdas are short functions: (n) -> print. They implement a functional interface (one abstract method). Streams let you filter/map/collect a list without a manual loop.

For 8 Features: generics keep types safe: List<String>. Autoboxing turns int into Integer when needed. varargs is String... args. Optional avoids some null checks — don’t overuse it.

Keep 8 Features small. Don’t dump business logic inside forEach. Know one tiny example you can write from memory.

Let's take this on the board with one tiny Main class — no extra files. Java 8 Features — output: [4, 16]. 1..5 → keep evens 2,4 → square → 4 and 16. Start from main, go line by line, and stop at each print. That output is the proof for 8 Features.

Exam tip

Explain map/filter/collect as a 3-step stream story.

Example

import java.util.*;
import java.util.stream.*;
public class Main {
  public static void main(String[] args) {
    List<Integer> nums = Arrays.asList(1, 2, 3, 4, 5);
    List<Integer> evenSq = nums.stream()
      .filter(n -> n % 2 == 0)
      .map(n -> n * n)
      .collect(Collectors.toList());
    System.out.println(evenSq); // [4, 16]
  }
}

Java 8 Features — output: [4, 16]. 1..5 → keep evens 2,4 → square → 4 and 16.

Short notes

Def8 Features is part of modern Java (generics / Java 8 style).
Rule8 Features — lambda = (args) -> body on a functional interface.
Use8 Features — streams filter/map/collect. Generics = List<String>.
Trap8 Features — huge logic inside lambdas, or forgetting generics.

import java.util.*; import java.util.stream.*; public class Main { public static void main(String[] args) { List<Integer> nums = Arrays.asList(1, 2, 3, 4, 5); List<Integer> evenSq = nums.stream() .filter(n -> n % 2 == 0) .map(n -> n * n) .collect(Collectors.toList()); System.out.println(evenSq); // [4, 16] } }

Java 8 Features

Example

Short notes

Questions

Java 8 Features

Example

Short notes

Questions