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Tuesday, 23 April 2013

Java code to insert,delete and display from Circular Queue

/*
Program for realisation of Circular Queue
*/
import java.io.*;
class circularQ
{
int Q[] = new int[100];
int n, front, rear;
static BufferedReader br = new BufferedReader(new
InputStreamReader(System.in));
public circularQ(int nn)
{
n=nn;
front = rear = 0;
}
public void add(int v)
{
if((rear+1) % n != front)
{
rear = (rear+1)%n;
Q[rear] = v;
}
else
System.out.println("Queue is full !");
}
public int del()
{
int v;
if(front!=rear)
{
front = (front+1)%n;
v = Q[front];
return v;
}
else
return -9999;
}
public void disp()
{
int i;
if(front != rear)
{
i = (front +1) %n;
while(i!=rear)
{
System.out.println(Q[i]);
i = (i+1) % n;
}
}
else
System.out.println("Queue is empty !");
}
public static void main() throws IOException
{
System.out.print("Enter the size of the queue : ");
int size = Integer.parseInt(br.readLine());
circularQ call = new circularQ(size);
int choice;
boolean exit = false;
while(!exit)
{
System.out.print("\n1 : Add\n2 : Delete\n3 : Display\n4 :
Exit\n\nYour Choice : ");
choice = Integer.parseInt(br.readLine());
switch(choice)
{
case 1 :
System.out.print("\nEnter number to be added : ");
int num = Integer.parseInt(br.readLine());
call.add(num);
break;
case 2 :
int popped = call.del();
if(popped != -9999)
System.out.println("\nDeleted : " +popped);
else
System.out.println("\nQueue is empty !");
break;
case 3 :
call.disp();
break;
case 4 :
exit = true;
break;
default :
System.out.println("\nWrong Choice !");
break;
}
}
}
}

/**
* Algorithm for Push :
* ------------------
* 1. Start
* 2. if((rear+1)%n = front) then queue is full (overflow)
*
else
* 3. rear = (rear+1)%n;
* 4. Q[rear] = v;
* 5. End
*
* Algorithm for pop :
* -----------------
* 1. Start
* 2. if(front == rear) then queue is empty (underflow)
*
else
* 3. front = (front+1)%n;
* 4. v = Q[front];
* 5. End
*/

/*
OUTPUT :
------
Enter the size of the queue : 5
1:Add
2:Delete
3:Display
4:Exit
Your Choice : 1
Enter number to be added : 35
....
....
...
...
..
.
*/



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