Jav Streams
Java Streams API. It allows you to drive away from Imperative Approach to Declarative Approach Programming.
Java Streams
Filter Methods:
- We Call the actual collection that we need
.stream()– this takes you to abstraction- You Can ask what you want of that list
- We have
.filter()method - We have to collect the result in the brand new list
- We used the
.collect()method - It takes
Collector.toList()
import java.util.Arrays; import java.util.List; import java.util.stream.Collectors; public class Main { public static void main(String[] args) { List < String > lines = Arrays.asList("Adam", "Olivia", "Amelia", "Harry"); List < String > result = lines.stream() .filter(line - > !"Harry".equals(line)) .collect(Collectors.toList()); result.forEach(System.out::println); } }
The Above code returns
Adam, Olivia, Amelia
Sort Methods
- Whenever we use the Declarative approach, we need to do abstraction mode
.stream()– this takes you to abstraction- We have
.sorted()method - It takes
Comparator.comparing()Comparator Method - It takes
Comparator.reverseOrder()Reversing Method - We have to collect the result in the brand new list
- We used the
.collect()method - It takes
Collector.toList() - If you want to reverse the output.Just add
.reversed()method
import java.util.Arrays; import java.util.Comparator; import java.util.List; import java.util.stream.Collectors; public class Main { public static void main(String[] args) { List < String > list = Arrays.asList("A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O"); List < String > sortedList = list.stream() .sorted(Comparator.reverseOrder()) .collect(Collectors.toList()); sortedList.forEach(System.out::println); } }
It returns the output in reverse order
O N M L K J I H G F E D C B A
- Streams Api Easy to work with Collections
- It tunes the performance as well
- It’s Better with a large amount of data
- It reduced the many lines of codes