How to use the ArrayDeque function to perform array deque operations in Java

In Java, ArrayDeque is an implementation of a double-ended queue, which can be used to perform double-ended queue operations on arrays. This article will introduce how to use the ArrayDeque function in Java to perform deque operations.

1. ArrayDeque function introduction

ArrayDeque is a way to implement a double-ended queue in Java. It can enter and exit the queue at both the head and the tail of the queue. operate. In the specific implementation, ArrayDeque takes the form of a dynamic array, which can automatically expand and contract as needed. ArrayDeque inherits from AbstractCollection and implements the Deque interface.

2. Create an ArrayDeque

In Java, we can use the ArrayDeque class to create a double-ended queue. The following is how ArrayDeque is created:

Deque<Integer> deque = new ArrayDeque<Integer>();

The above code defines a double-ended queue of type Integer, which we can use to perform double-ended queue operations.

3. Basic operations of double-ended queue

3.1 Enqueue operation

In ArrayDeque, we can use the addFirst() function to insert elements at the head of the queue , use the addLast() function to insert elements at the end of the queue, as shown below:

deque.addFirst(1);
deque.addLast(2);

The above code adds two elements to the double-ended queue, 1 and 2, added to the head and tail of the queue respectively.

3.2 Dequeue operation

In ArrayDeque, we can use the pollFirst() function to take out elements from the head of the queue, and use the pollLast() function to take out elements from the tail of the queue, as shown below:

int element1 = deque.pollFirst();
int element2 = deque.pollLast();

The above code takes out two elements from the double-ended queue, taking out element 1 at the head of the queue and element 2 at the tail of the queue.

3.3 Get the elements at the head and tail of the queue

In ArrayDeque, we can use the getFirst() function to get the head element and the getLast() function to get the tail element, as shown below :

int headElement = deque.getFirst();
int tailElement = deque.getLast();

The above code obtains the head element and tail element of the double-ended queue.

4. Traversing the deque

We can also use iterators in Java to traverse the elements in the deque, as shown below:

Iterator<Integer> iterator = deque.iterator();
while (iterator.hasNext()) {
   int element = iterator.next();
   System.out.println(element);
}

The above code uses an iterator to traverse all elements in the deque and then output them one by one.

5. Summary

Through the above introduction, we can use the ArrayDeque function in Java to perform array double-ended queue operations. We can use the addFirst() and addLast() functions to add elements to the deque, use the pollFirst() and pollLast() functions to remove elements from the head and tail of the queue, and use the getFirst() and getLast() functions to obtain the head and tail of the queue. The tail element of the queue, using an iterator to traverse the elements in the deque. Through these operations, we can easily implement the function of double-ended queue.

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