Stream forEachOrdered() method in Java with examples

Last Updated : 06 Dec, 2018

Stream forEachOrdered(Consumer action) performs an action for each element of this stream, in the encounter order of the stream if the stream has a defined encounter order. Stream forEachOrdered(Consumer action) is a terminal operation i.e, it may traverse the stream to produce a result or a side-effect.

Syntax :

void forEachOrdered(Consumer<? super T> action)

Where, Consumer is a functional interface which 
is expected to operate via side-effects. and T 
is the type of stream elements.

Note : This operation processes the elements one at a time, in encounter order if one exists. Performing the action for one element happens-before performing the action for subsequent elements.

Example 1 : To print the elements of integer array in original order.

// Java code for forEachOrdered 
// (Consumer action) in Java 8 
import java.util.*; 
  
class GFG { 
      
    // Driver code 
    public static void main(String[] args) { 
  
    // Creating a list of Integers 
    List<Integer> list = Arrays.asList(10, 19, 20, 1, 2); 
      
    // Using forEachOrdered(Consumer action) to  
    // print the elements of stream in encounter order 
    list.stream().forEachOrdered(System.out::println); 
      
  
} 
} 

Output:

Example 2 : To print the elements of string array in original order.

// Java code for forEachOrdered 
// (Consumer action) in Java 8 
import java.util.*; 
  
class GFG { 
      
    // Driver code 
    public static void main(String[] args) { 
  
    // Creating a list of Strings 
    List<String> list = Arrays.asList("GFG", "Geeks",  
                             "for", "GeeksforGeeks"); 
      
    // Using forEachOrdered(Consumer action) to  
    // print the elements of stream in encounter order 
    list.stream().forEachOrdered(System.out::println); 
      
  
} 
} 

Output:

GFG
Geeks
for
GeeksforGeeks

Example 3 : To print the characters at index 2 of string array in original order.

// Java code for forEachOrdered 
// (Consumer action) in Java 8 
import java.util.*; 
import java.util.stream.Stream; 
  
  
class GFG { 
      
    // Driver code 
    public static void main(String[] args) { 
  
    // Creating a Stream of Strings 
    Stream<String> stream = Stream.of("GFG", "Geeks",  
                             "for", "GeeksforGeeks"); 
      
    // Using forEachOrdered(Consumer action)  
    stream.flatMap(str-> Stream.of(str.charAt(2))) 
          .forEachOrdered(System.out::println); 
      
  
} 
} 