Java Program: Sort List of Strings in Ascending and Descending Order using Streams

Java Stream: Exercise-6 with Solution

Write a Java program to sort a list of strings in alphabetical order, ascending and descending using streams.

Sample Solution:

Java Code:

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 > colors = Arrays.asList("Red", "Green", "Blue", "Pink", "Brown");
    System.out.println("Original List of strings(colors): " + colors);
    // Sort strings in ascending order
    List < String > ascendingOrder = colors.stream()
      .sorted()
      .collect(Collectors.toList());

    // Sort strings in descending order
    List < String > descendingOrder = colors.stream()
      .sorted(Comparator.reverseOrder())
      .collect(Collectors.toList());

    System.out.println("\nSorted in Ascending Order: " + ascendingOrder);
    System.out.println("\nSorted in Descending Order: " + descendingOrder);
  }
}

Sample Output:

Original List of strings(colors): [Red, Green, Blue, Pink, Brown]

Sorted in Ascending Order: [Blue, Brown, Green, Pink, Red]

Sorted in Descending Order: [Red, Pink, Green, Brown, Blue]

Explanation:

In the above exercise,

Using streams, we call the sorted() method without passing any comparator to sort the strings in ascending order based on their natural order (lexicographically). We collect the sorted strings into a new list using the toList() method.

To sort the strings in descending order, we pass Comparator.reverseOrder() as the comparator to the sorted() method. This reverses the natural order and sorts the strings in descending order.

Flowchart:

Java Code Editor:

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