Java Stream sorted() Example

1. Introduction

This tutorial explores the sorted() method in the Java Stream API. The sorted() method is an intermediate operation that sorts the elements of a stream into a specified order. It can use natural ordering or a provided Comparator.

Key Points

1. sorted() sorts the elements of the stream.

2. It can use natural ordering or a custom order defined by a Comparator.

3. Sorting is a common operation to prepare data for further processing, such as display or sequential analysis.

2. Program Steps

1. Create a Stream of elements.

2. Apply the sorted() method using natural ordering or a custom Comparator.

3. Collect or process the sorted stream to demonstrate its effects.

3. Code Program

import java.util.Comparator;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;

public class StreamSortedExample {

    public static void main(String[] args) {
        // Stream of integers
        Stream<Integer> numberStream = Stream.of(5, 3, 9, 1, 4);

        // Sort the stream in natural order
        List<Integer> sortedNumbers = numberStream.sorted().collect(Collectors.toList());
        System.out.println("Sorted numbers (natural order): " + sortedNumbers);

        // Stream of strings
        Stream<String> stringStream = Stream.of("banana", "apple", "cherry", "date");

        // Sort the stream using a custom comparator
        List<String> sortedStrings = stringStream.sorted(Comparator.reverseOrder()).collect(Collectors.toList());
        System.out.println("Sorted strings (reverse order): " + sortedStrings);
    }
}

Output:

Sorted numbers (natural order): [1, 3, 4, 5, 9]
Sorted strings (reverse order): [date, cherry, banana, apple]

Explanation:

1. Stream.of(5, 3, 9, 1, 4) creates a stream of integers.

2. numberStream.sorted() sorts the integers in natural ascending order.

3. sortedNumbers.collect(Collectors.toList()) collects the sorted numbers into a list and prints them.

4. Stream.of("banana", "apple", "cherry", "date") creates a stream of strings.

5. stringStream.sorted(Comparator.reverseOrder()) sorts the strings in descending order using a reverse order comparator.

6. sortedStrings.collect(Collectors.toList()) collects the sorted strings into a list and prints them in reverse alphabetical order.