Deque descendingIterator() method in Java
The descendingIterator(E e) method of Deque Interface returns an iterator over the elements in this deque in a reverse sequential order. The elements will be returned in order from last(tail) to first(head). The returned iterator is a “weakly consistent” iterator.
Syntax:
Iterator descendingIterator()
Parameters: This method does not accept any parameter.
Return Value: This method returns an iterator over the elements in this deque in a proper sequence
Below programs illustrate the descendingIterator() method in Java:
Program 1: With the help of LinkedList.
// Java code to illustrate descendingIterator() // method of Deque in Java import java.util.*; public class GFG { public static void main(String args[]) { // Creating an empty Deque Deque<String> de_que = new LinkedList<String>(); // Use add() method to add elements into the Queue de_que.add("Welcome"); de_que.add("To"); de_que.add("Geeks"); de_que.add("4"); de_que.add("Geeks"); // Call iterator() method of deque Iterator iteratorVals = de_que.iterator(); // Print elements of iterator // created from PriorityBlockingQueue System.out.println("The iterator values" + " of deque are:"); // prints the elements using an iterator while (iteratorVals.hasNext()) { System.out.println(iteratorVals.next()); } } } |
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Output:
The iterator values of deque are: Welcome To Geeks 4 Geeks
Program 2:
// Java code to illustrate descendingIterator() // method of Deque in Java import java.util.*; public class GFG { public static void main(String args[]) { // Creating an empty Deque Deque<Integer> de_que = new LinkedList<Integer>(); // Use add() method to add elements into the Queue de_que.add(10); de_que.add(15); de_que.add(30); de_que.add(20); de_que.add(5); // Call iterator() method of deque Iterator iteratorVals = de_que.iterator(); // Print elements of iterator // created from PriorityBlockingQueue System.out.println("The iterator values" + " of deque are:"); // prints the elements using an iterator while (iteratorVals.hasNext()) { System.out.println(iteratorVals.next()); } } } |
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Output:
The iterator values of deque are: 10 15 30 20 5
Program 3: With the help of ArrayDeque.
// Java code to illustrate descendingIterator() // method of Deque in Java import java.util.*; public class GFG { public static void main(String args[]) { // Creating an empty Deque Deque<String> de_que = new ArrayDeque<String>(); // Use add() method to add elements into the Queue de_que.add("Welcome"); de_que.add("To"); de_que.add("Geeks"); de_que.add("4"); de_que.add("Geeks"); // Call iterator() method of deque Iterator iteratorVals = de_que.iterator(); // Print elements of iterator // created from PriorityBlockingQueue System.out.println("The iterator values" + " of deque are:"); // prints the elements using an iterator while (iteratorVals.hasNext()) { System.out.println(iteratorVals.next()); } } } |
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Output:
The iterator values of deque are: Welcome To Geeks 4 Geeks
Program 4: With the help of LinkedBlockingDeque.
// Java code to illustrate descendingIterator() // method of Deque in Java import java.util.*; import java.util.concurrent.LinkedBlockingDeque; public class GFG { public static void main(String args[]) { // Creating an empty Deque Deque<String> de_que = new LinkedBlockingDeque<String>(); // Use add() method to add elements into the Queue de_que.add("Welcome"); de_que.add("To"); de_que.add("Geeks"); de_que.add("4"); de_que.add("Geeks"); // Call iterator() method of deque Iterator iteratorVals = de_que.iterator(); // Print elements of iterator // created from PriorityBlockingQueue System.out.println("The iterator values" + " of deque are:"); // prints the elements using an iterator while (iteratorVals.hasNext()) { System.out.println(iteratorVals.next()); } } } |
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Output:
The iterator values of deque are: Welcome To Geeks 4 Geeks
Program 5: With the help of ConcurrentLinkedDeque.
// Java code to illustrate descendingIterator() // method of Deque in Java import java.util.*; import java.util.concurrent.ConcurrentLinkedDeque; public class GFG { public static void main(String args[]) { // Creating an empty Deque Deque<String> de_que = new ConcurrentLinkedDeque<String>(); // Use add() method to add elements into the Queue de_que.add("Welcome"); de_que.add("To"); de_que.add("Geeks"); de_que.add("4"); de_que.add("Geeks"); // Call iterator() method of deque Iterator iteratorVals = de_que.iterator(); // Print elements of iterator // created from PriorityBlockingQueue System.out.println("The iterator values" + " of deque are:"); // prints the elements using an iterator while (iteratorVals.hasNext()) { System.out.println(iteratorVals.next()); } } } |
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Output:
The iterator values of deque are: Welcome To Geeks 4 Geeks
Reference: https://docs.oracle.com/javase/8/docs/api/java/util/Deque.html#descendingIterator–
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