Queues Using Arrays
/*Copyrights to vsdevelopers.io*/
/*For more programs visit vsdevelopers.io */
/*Java program for queue operations using array*/
/*The operations are Create, Insert,Delete, Search, Destroy*/
import java.util.Scanner;
public class VSDQueueArray {
static Scanner sc = new Scanner(System.in);
static int size;// size of queue
static int queue[];// queue array
static int rear = -1;// rear end of the queue
static int front = -1;// starting of queue
// Function to create a queue
public static void VSDcreateQueue() {
System.out.println(“Enter size of queue”);
size = sc.nextInt();
queue = new int[size];
}
// Function to insert element into the queue
public static void VSDinsert() {
if (queue == null)// Checking whether the queue exists or not
{
System.out.println(“Queue doesnot exist, Create the queue”);
return;
}
if (rear == size – 1) // Checking for filled queue
System.out.println(“Cannot insert the element, Queue is full”);
else {
System.out.println(“Please Enter element to insert:”);
int element = sc.nextInt();
queue[++rear] = element;// Inserting the element and updating the rear
if (front == -1)
front++;
}
VSDprintQueue();
}
// Function to delete element into the queue
public static void VSDdelete() {
if (queue == null)// Checking whether the queue exists or not
{
System.out.println(“Queue doesnot exist, Create the queue”);
return;
}
if (rear == -1)// Checking if queue is empty
System.out.println(“Queue is empty”);
else {
int element = queue[front];
for (int i = front; i < rear; i++) {
queue[i] = queue[i + 1];
}
queue[rear] = 0;
rear--;
System.out.println("The deleted element is:" + element);
}
VSDprintQueue();
}
// Function to search element in queue
public static void VSDsearch() {
if (queue == null)// Checking whether the queue exists or not
{
System.out.println("Queue doesnot exist, Create the queue");
return;
}
if (rear == -1)// Checking if queue is empty
System.out.println("Queue is empty");
else {
System.out.println("Please Enter element to serach:");
int element = sc.nextInt();
int flag = 0;// For marking presence of elements
for (int i = 0; i <= rear; i++) {
if (element == queue[i]) {
System.out.println("Element is present at index: " + i);
flag = 1;
}
}
if (flag == 0)
System.out.println("Element is not present in queue");
}
}
// Function to destroy queue
public static void VSDdestroy() {
queue = null;
System.out.println("Queue is destroyed");
}
// Function to print the Queue
public static void VSDprintQueue() {
System.out.println("Now the queue is");
if (rear == -1)
System.out.println("Queue is Empty!!!");
for (int i = front; i <= rear; i++)
System.out.println(queue[i]);
}
// Function to take user input
public static void VSDuserInput() {
System.out.println("Please Enter queue operation from:");
System.out.println("Create Insert Delete Search Destroy");
String choice = sc.next();
switch (choice) {
case "Create":
case "create":
VSDcreateQueue();
break;
case "Insert":
case "insert":
VSDinsert();
break;
case "Delete":
case "delete":
VSDdelete();
break;
case "Search":
case "search":
VSDsearch();
break;
case "Destroy":
case "destroy":
VSDdestroy();
break;
}
VSDuserChoice();
}
public static void VSDuserChoice() {
System.out.println("For performing operations enter y else enter n");
char ch = sc.next().charAt(0);
if (ch == 'Y' || ch == 'y')
VSDuserInput();
else
return;
}
public static void main(String args[]) {
VSDcreateQueue();// Creating queue initially
VSDuserInput();// Taking user input to perform queue operations
}
}
/java]
