Java ConcurrentLinkedQueue forEach() Method

The forEach() method of ConcurrentLinkedQueue class executes the specified action for each element of Iterable, until all the elements are processed, or the action throws an exception.

Syntax:

Parameters:

action - this is the action to be performed for every element.

Specified By:

The forEach() method of ConcurrentLinkedQueue class is specified by :

forEach() method in interface Iterable<E>.

Throws:

The forEach() method throws NullPointerException if the defined action represents null.

Example 1

import java.util.concurrent.ConcurrentLinkedQueue;
public class ConcurrentLinkedQueueForEachExample1 {
    public static void main(String[] args) {
        ConcurrentLinkedQueue<String> queue = new ConcurrentLinkedQueue<String>();
        queue.add("Reema");
        queue.add("Rahul");
        queue.add("Rita");
        queue.add("Ramesh");
        System.out.println(queue);
        System.out.println("\nPrinting the queue with the help of foreach loop : ");
        //foreach() will perform the given action for each element
        for (String xyz: queue) {
            System.out.println(xyz);
        }
    }
}

Test it Now

Output:

[Reema, Rahul, Rita, Ramesh]

Printing the queue with the help of foreach loop : 
Reema
Rahul
Rita
Ramesh

Example 2

import java.util.concurrent.ConcurrentLinkedQueue;
public class ConcurrentLinkedQueueForEachExample2 {
    public static void main(String[] args) {
        Student student1 = new Student("15cs1029", "MVN University", "Reema");
        Student student2 = new Student("15cs1010", "MVN University", "Geetanjali");
        Student student3 = new Student("17cs1029", "MR University", "Vineet");
        Student student4 = new Student("15cs1011", "MVN University", "Himanshu");
        ConcurrentLinkedQueue<Student> queue = new ConcurrentLinkedQueue<Student>();
        queue.add(student1);
        queue.add(student2);
        queue.add(student3);
        queue.add(student4);
        //foreach() will perform the given action for each element
        for (Student xyz : queue) {
            System.out.println(xyz);
        }
    }
}
class Student {
    static int i = 1;
    public String name;
    public String college;
    String rollNo;

    Student(String rollNo, String college, String name) {
        this.rollNo = rollNo;
        this.name = name;
        this.college = college;
    }
    public String toString() {
        return i++ + ".Roll No. =  " + this.rollNo + "\n  College =  " + this.college + "\n  Name = " + this.name + "\n";
    }
}

Test it Now

Output:

1.Roll No. =  15cs1029
  College =  MVN University
  Name = Reema

2.Roll No. =  15cs1010
  College =  MVN University
  Name = Geetanjali

3.Roll No. =  17cs1029
  College =  MR University
  Name = Vineet

4.Roll No. =  15cs1011
  College =  MVN University
  Name = Himanshu

Example 3

import java.util.concurrent.ConcurrentLinkedQueue;
public class ConcurrentLinkedQueueForEachExample3 {
    static int i =0;
    public static void main(String[] args) {
        ConcurrentLinkedQueue<String> queue = new  ConcurrentLinkedQueue<String>();
        queue.add("reema");
        queue.add("sonia");
        //foreach() will perform the given action for each element
        for (String val : queue) {
            String upperCase = val.toUpperCase();
            System.out.println(++i + " Lower case = " + val);
            System.out.println("  Upper case = " + upperCase);
            System.out.println();
        }
    }
}

Test it Now

Output:

1 Lower case = reema
  Upper case = REEMA

2 Lower case = sonia
  Upper case = SONIA

Example 4

import java.util.concurrent.ConcurrentLinkedQueue;
public class ConcurrentLinkedQueueForEachExample4 {
    public static void main(String[] args) {
        ConcurrentLinkedQueue<String> queue = new ConcurrentLinkedQueue<String>();
        queue.add(null);
        System.out.println("\nPrinting the queue with the help of foreach loop : ");
        //foreach() will perform the given action for each element
        for (String xyz: queue) {
            System.out.println(xyz);
        }
    }
}

Test it Now

Output:

Exception in thread "main" java.lang.NullPointerException
	at java.util.concurrent.ConcurrentLinkedQueue.checkNotNull(ConcurrentLinkedQueue.java:920)
	at java.util.concurrent.ConcurrentLinkedQueue.offer(ConcurrentLinkedQueue.java:327)
	at java.util.concurrent.ConcurrentLinkedQueue.add(ConcurrentLinkedQueue.java:297)
	at com.javaTpoint.ConcurrentLinkedQueueForEachExample4.main(ConcurrentLinkedQueueForEachExample4.java:7)

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