Deque iterator() method in Java

Last Updated : 20 Jun, 2020

The iterator() method of Deque Interface returns an iterator over the elements in this deque in a proper sequence. The elements will be returned in order from first (head) to last (tail). The returned iterator is a “weakly consistent” iterator. Syntax:

Iterator iterator()

Parameters: This method does not accepts any parameter. Returns: This method returns an iterator over the elements in this deque in a proper sequence. Below programs illustrate iterator() method of Deque: Program 1: With the help of ArrayDeque.

Java

// Java Program Demonstrate iterator()
// method of Deque
import java.util.*;

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

        // create object of Deque
        Deque<Integer> DQ
            = new ArrayDeque<Integer>();

        // Add numbers to end of Deque
        DQ.add(7855642);
        DQ.add(35658786);
        DQ.add(5278367);
        DQ.add(74381793);

        // Call iterator() method of Deque
        Iterator iteratorVals = DQ.iterator();

        // Print elements of iterator
        // created from Deque
        System.out.println("The iterator values"
                           + " of Deque are:");

        // prints the elements using an iterator
        while (iteratorVals.hasNext()) {
            System.out.println(iteratorVals.next());
        }
    }
}

Output:

The iterator values of Deque are:
7855642
35658786
5278367
74381793

Program 2: With the help of LinkedList.

Java

// Java Program Demonstrate iterator()
// method of Deque
import java.util.*;

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

        // create object of Deque
        Deque<Integer> DQ
            = new LinkedList<Integer>();

        // Add numbers to end of Deque
        DQ.add(7855642);
        DQ.add(35658786);
        DQ.add(5278367);
        DQ.add(74381793);

        // Call iterator() method of Deque
        Iterator iteratorVals = DQ.iterator();

        // Print elements of iterator
        // created from Deque
        System.out.println("The iterator values"
                           + " of Deque are:");

        // prints the elements using an iterator
        while (iteratorVals.hasNext()) {
            System.out.println(iteratorVals.next());
        }
    }
}

Output:

The iterator values of Deque are:
7855642
35658786
5278367
74381793

Program 3: With the help of LinkedBlockingDeque.

Java

// Java Program Demonstrate iterator()
// method of Deque
import java.util.*;
import java.util.concurrent.LinkedBlockingDeque;

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

        // create object of Deque
        Deque<Integer> DQ
            = new LinkedBlockingDeque<Integer>();

        // Add numbers to end of Deque
        DQ.add(7855642);
        DQ.add(35658786);
        DQ.add(5278367);
        DQ.add(74381793);

        // Call iterator() method of Deque
        Iterator iteratorVals = DQ.iterator();

        // Print elements of iterator
        // created from Deque
        System.out.println("The iterator values"
                           + " of Deque are:");

        // prints the elements using an iterator
        while (iteratorVals.hasNext()) {
            System.out.println(iteratorVals.next());
        }
    }
}

Output:

The iterator values of Deque are:
7855642
35658786
5278367
74381793

Program 4: With the help of ConcurrentLinkedDeque.

Java

// Java Program Demonstrate iterator()
// method of Deque
import java.util.*;
import java.util.concurrent.ConcurrentLinkedDeque;

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

        // create object of Deque
        Deque<Integer> DQ
            = new ConcurrentLinkedDeque<Integer>();

        // Add numbers to end of Deque
        DQ.add(7855642);
        DQ.add(35658786);
        DQ.add(5278367);
        DQ.add(74381793);

        // Call iterator() method of Deque
        Iterator iteratorVals = DQ.iterator();

        // Print elements of iterator
        // created from Deque
        System.out.println("The iterator values"
                           + " of Deque are:");

        // prints the elements using an iterator
        while (iteratorVals.hasNext()) {
            System.out.println(iteratorVals.next());
        }
    }
}

Output:

The iterator values of Deque are:
7855642
35658786
5278367
74381793

Reference: https://docs.oracle.com/javase/8/docs/api/java/util/Deque.html#iterator--

Deque offer() method in Java

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