There are three main features in Java 8 that I love, one of them is the lambda expressions, it will have enormous implications for simplifying development. The another one is the new java.util.stream package provide a Stream API to support functional-style operations on streams of elements. The Stream API is integrated into the Collections API, which enables bulk operations on collections, such as sequential or parallel map-reduce transformations. And lastly but not least the java.time API that now are compatible with lambda, thread safe and simplified usage.
- Java Time API
- Streams
- Stream Filters
- Stream Collectors
- Executors
- Generics
- Functional Interfaces
- Lambda Expressions
- Junit 5
- From Anonymous to Lambda
- JFairy Data Generator
- Using Optional
- Builder Desing Pattern
- Mailosaur Getting Started
- GitHub Repository
forEach() in a Map
Iterate over a collection in Java 8 is a really nice one, which lets you pass a method reference or a lambda to receive (key, value) pairs one by one.
import java.util.Map;
import java.util.HashMap;
class ForEachMap {
void iterate(Map<String, Integer> items){
items.forEach((k,v) -> System.out.println("Item : " + k + " Count : " + v));
}
public static void main(String[] args){
Map<String, Integer> items = new HashMap<>();
items.put("A", 10);
items.put("B", 20);
items.put("C", 30);
new ForEachMap().iterate(items);
}
}
output
Item : A Count : 10
Item : B Count : 20
Item : C Count : 30
forEach() in a List
Also, you can loop a List with forEach
import java.util.List;
import java.util.ArrayList;
class ForEachList {
void iterate(List<String> items){
items.forEach(System.out::println);
}
public static void main(String[] args){
List<String> items = new ArrayList<String>();
items.add("A");
items.add("B");
items.add("C");
new ForEachList().iterate(items);
}
}
output
A
B
C
NOTE: You can get item from collection like this: items.forEach(item -> System.out.println(item));
You can iterate a Set in the same way