Stream sorted() in Java

Stream sorted() returns a stream consisting of the elements of this stream, sorted according to natural order. For ordered streams, the sort method is stable but for unordered streams, no stability is guaranteed. It is a stateful intermediate operation i.e, it may incorporate state from previously seen elements when processing new elements.

Syntax :

Stream<T> sorted()

Where, Stream is an interface and T
is the type of stream elements.

Exception : If the elements of this stream are not Comparable, a java.lang.ClassCastException may be thrown when the terminal operation is executed.

Below given are some examples to understand the implementation of the function in a better way.

Example 1 :

// Implementation of Stream.sorted()
// to get a stream of elements
// sorted in their natural order
import java.util.*;

class GFG {

    // Driver code
    public static void main(String[] args)
    {

        // Creating a list of integers
        List<Integer> list = Arrays.asList(-9, -18, 0, 25, 4);

        System.out.println("The sorted stream is : ");

        // displaying the stream with elements
        // sorted in natural order
        list.stream().sorted().forEach(System.out::println);
    }
}

Output:

The sorted stream is : 
-18
-9
0
4
25

Example 2 :

// Implementation of Stream.sorted()
// to get a stream of elements
// sorted in their natural order
import java.util.*;

class GFG {

    // Driver code
    public static void main(String[] args)
    {

        // Creating a list of strings
        List<String> list = Arrays.asList("Geeks", "for",
                     "GeeksQuiz", "GeeksforGeeks", "GFG");

        System.out.println("The sorted stream is : ");

        // displaying the stream with elements
        // sorted in their natural order
        list.stream().sorted().forEach(System.out::println);
    }
}

Output:

The sorted stream is : 
GFG
Geeks
GeeksQuiz
GeeksforGeeks
for

Example 3 :

// Using stream sorted to sort a stream
// of user defined class objects
import java.util.*;

class Point
{
    Integer x, y;
    Point(Integer x, Integer y) {
        this.x = x;
        this.y = y;
    }

    public String toString() {
        return this.x + ", "+ this.y;
    }
}

class GFG
{
    public static void main(String[] args)
    {

        List<Point> aList = new ArrayList<>();
        aList.add(new Point(10, 20));
        aList.add(new Point(5, 10));
        aList.add(new Point(1, 100));
        aList.add(new Point(50, 2000));

        // displaying the stream with elements
        // sorted according to x coordinate
        aList.stream()
        .sorted((p1, p2)->p1.x.compareTo(p2.x))
        .forEach(System.out::println);
    }
}

Output:

1, 100
5, 10
10, 20
50, 2000