Stream sorted() method in Java

A Stream sorted() method used to sort stream elements in to the specified order. If order not specified, it sorts elements in ascending order. It takes Consumer object that can be a method reference or a lambda expression. It is an intermediate operation that returns a Stream object that includes sorted elements of Stream.

Syntax

 1 Stream<T> sorted()
 2 Stream<T> sorted(Comparator<? super T> comparator);

T : It represents a type of Stream elements that will be sorted.

comparator : It is an instance of comparator, if order of sorted() method needs to be change. If not specified, the default order will be ascending order.

Stream sorted() method

 1 package com.java;
 2 
 3 import java.util.Arrays;
 4 import java.util.List;
 5 
 6 public class Example {
 7     public static void main(String[] args) {
 8 
 9         List<String> strings = Arrays.asList("String", "Java", "Watch");
 10         strings.stream().sorted()
 11                 .forEach(System.out::println);
 12     }
 13 }

In the above example, a list object is stream using stream() method. A sorted() method sort each Stream elements into ascending order and returns a Stream object that includes sorted strings. A Stream object with sorted strings will be print using Stream forEach() method.

Output

 1 Java
 2 String
 3 Watch

Stream sorted() method with comparator

 1 package com.java;
 2 
 3 import java.util.Arrays;
 4 import java.util.Comparator;
 5 import java.util.List;
 6 
 7 public class Example {
 8     public static void main(String[] args) {
 9 
 10         List<String> strings = Arrays.asList("String", "Java", "Watch");
 11         
 12         strings.stream().sorted(Comparator.reverseOrder())
 13                 .forEach(System.out::println);
 14     }
 15 }

In the above example, a Stream sorted() method called by passing a Comparator object. A Comparator reverseOrder() method returns an instance of Comparator object. It sort Stream elements in reverse order and returns Stream object. A Stream elements will be print using forEach() method.

Output

 1 Watch
 2 String
 3 Java

Stream sorted() method with numbers

 1 package com.java;
 2 
 3 import java.util.Arrays;
 4 import java.util.List;
 5 
 6 public class Example {
 7     public static void main(String[] args) {
 8 
 9         List<Integer> strings = Arrays.asList(20, 10, 50, 40);
 10 
 11         strings.stream().sorted()
 12                 .forEach(System.out::println);
 13     }
 14 }

In the above example, a list object is define with integer values. A Stream sorted() function is called that sort Stream elements in ascending order and returns a Stream object that includes sorted intgers. A sorted Stream object element will be printed using forEach() method,

Output

Stream sorted() with custom comparator

 1 package com.java;
 2 
 3 import java.util.Arrays;
 4 import java.util.List;
 5 
 6 public class Example {
 7     public static void main(String[] args) {
 8 
 9         List<Integer> strings = Arrays.asList(20, 10, 50, 40);
 10 
 11         strings.stream().sorted((n1, n2) -> n2 - n1)
 12                 .forEach(System.out::println);
 13     }
 14 }

In the above example, a sorted() method sort each element of Stream based on custom Comparator and returns Stream object that include descending order numbers. A custom comparator sort elements in descending order. A Stream object elements printed using forEach() method.

Output

Stream sorted() with Custom object

 1 package com.java;
 2 
 3 import java.util.ArrayList;
 4 import java.util.List;
 5 
 6 class Model {
 7     private String name;
 8     private Integer price;
 9 
 10     public Model(String name, Integer price) {
 11         this.name = name;
 12         this.price = price;
 13     }
 14 
 15     public String getName() {
 16         return this.name;
 17     }
 18 
 19     public Integer getPrice() {
 20         return this.price;
 21     }
 22 
 23     public String toString() {
 24         return this.name + " = " + this.price;
 25     }
 26 }
 27 public class Example {
 28     public static void main(String[] args) {
 29 
 30         List<Model> models = new ArrayList<>();
 31         models.add(new Model("Java", 1000));
 32         models.add(new Model("Javascript", 1200));
 33 
 34         models.stream().sorted((n1, n2) -> n2.getPrice() - n1.getPrice())
 35                 .forEach(System.out::println);
 36     }
 37 }

In the above example, a custom class Model is created that has two properties name and price. An list object is created with two Model object. A sorted() method sort Stream elements in descending order based on price property. It returns a Stream that contain sorted Model object in descending order. A resulting Stream object elements printed using forEach() method.

Output