Queue in java

Queue:-queue is used in data structure to insert data at the end and remove at top.

following are complete example of queue.


public class Queue {
int rear=-1;
int front=-1;
int size;
int qArr[];
Queue (){ size=10; qArr=new int[size];  }
Queue (int a){ size=a; qArr=new int[size];  }
public boolean  isEmpty()
                   {
if(rear==front)
return true;
else
return false;
                 }
public boolean isfull() {
if(rear==size-1)
return true;
else
return false;   }
public void enqueue(int n)
{

if(isfull())
{
System.out.println("Queue is full.");
}
else {
if(front==-1)
front++;

rear++;
qArr[rear]=n;
       }
}

public int dequeue()
{int temp=-9999;
if(isEmpty())
{

System.out.println("Stack is empty!");

}
else {
temp=qArr[front];
qArr[front]=-999;
front++;

}
return temp;
}

public void display()
{
for(int i=front;i<=rear;i++)
System.out.println(qArr[i]);

}
public  static void main(String args[]) {
Queue Q=new Queue(7); //will create Q of size 7.

System.out.println("//when queue is empty and performed dequeue.");
    Q.dequeue();     //output stack is empty
    System.out.println("//.......................");
Q.enqueue(34);    //at 1 position
Q.enqueue(35);   //at 2 position
Q.enqueue(36);   //at 3 position
Q.enqueue(37);   //at 4 position
Q.enqueue(38);   //at 5 position
        Q.enqueue(39);   //at 6 position
        Q.enqueue(40);    //at 7 position
        System.out.println("//when queue is full.");
        Q.enqueue(50);    //at 8 position which is no exist.
        // verification 50 are added or not.
     
        System.out.println("//displaying");
        Q.display();//50 are not added.
        System.out.println("//.......................");
        Q.dequeue();
        System.out.println("//after dequeue 34");
Q.display();
}

}