Java Queue Example

Chapter: Miscellaneous Last Updated: 28-05-2016 13:02:02 UTC

Program:

            /* ............... START ............... */
                
public class JavaQueueExample {

	int Q[]; // Array to implement Queue
	int size; // Maximum size of the Queue
	int front; // Index of front element
	int rear; // Index of rear element

	JavaQueueExample(int cap) // Parameterised Constructor
	{
		size = cap;
		Q = new int[size];
		front = 0;
		rear = 0;
	}

	void insert(int v) // Function to insert element in Queue
	{
		if (rear == size) // Condition for Overflow
		{
			System.out.println("OVERFLOW");
		} else {
			Q[rear] = v; // Storing value in Queue
			rear = rear + 1;
		}
	}

	int delete() // Function to delete element from Queue
	{
		if (front == 0 && rear == 0) // Condition for Underflow
		{
			System.out.println("UNDERFLOW");
			return -999;
		} else {
			int val = Q[front]; // Storing the element which will be removed
			front = front + 1;
			if (front == rear) // Condition for emptying the Queue
			{
				front = 0;
				rear = 0;
			}
			return val;
		}
	}

	void display() // Function for printing elements in the queue
	{
		if (front == 0 && rear == 0) {
			System.out.println("The Queue is empty");
		} else {
			System.out.println("The elements in the queue are : ");
			for (int i = front; i < rear; i++) {
				System.out.println(Q[i]);
			}
		}
	}
}

                /* ............... END ............... */
        

Notes:

  • Queue is a linear data structure which enables the user to add elements from the rear end and remove elements from the front end only.
  • Queue uses the concept of FIFO (First In First Out).

Tags

Java Queue Example, Java

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