Queue Java Program Using Exception

Queue Java Program Using Exception

Queue - first in first out

import java.util.*; 

class Jqueue{ 
  public int count = 0;   
  public int element; 
  Scanner Sc=new Scanner(System.in); 
  int n=Sc.nextInt();   
  int []a=new int[n]; 
  void enqueue() 
  { 
   try 
   { 
 	System.out.print("Enter the element: "); 
 	a[count++]=Sc.nextInt(); 
   } 
   catch(Exception e) 
   { 
 	System.out.println(e+ "the queue is full"); 
   } 
  } 
  void dequeue() 
  { 
   try 
   { 
 	System.out.println("the deleted element is"+a[0]); 
        for(int i=0; i<count-1; i++)
         {
             a[i] = a[i+1];
         }
         a[count-1] =0;
         count -= 1;
        
   } 
   catch(Exception e) 
   {  
 	System.out.println(e +"the queue is empty"); 
   } 
  } 
  void  display() 
  { 
   try 
   { 
 	for(int i=0;i<count;++i) 
 	{ 
 	System.out.println("Elements in queue are" + a[i]); 
 	} 
   } 
   catch(Exception j) 
   { 
 	System.out.println(j+"the queue is  empty"); 
   } 
  }  
} 
class queue 
{ 
 public static void main(String args[]) 
 { 
  int opt,v;  
  Scanner S=new Scanner(System.in); 
  System.out.println("Enter queue size: ");
  Jqueue A=new Jqueue(); 
  System.out.println("\nqueue\n1.enqueue\n2.dequeue\n3.display"); 
  do 
  { 
 	System.out.println("Enter the choice"); 
 	opt=S.nextInt(); 
 	switch(opt) 
 	{ 
 	case 1: 
 	 A.enqueue();  	
         break;  	
        case 2:  
 	 A.dequeue();  	
         break;  	
        case 3: 
 	 A.display();  	
         break;  	
        default: 
 	 System.out.println("invalid"); 
 	 break; 
 	} 
       System.out.println("do you wish to contnue(1/0)?"); 
       v=S.nextInt();
  }while(v==1); 
 } 
} 
 

$ javac queue.java

$ java queue
Enter queue size:
5

queue
1.enqueue
2.dequeue
3.display
Enter the choice
1
Enter the element: 23
do you wish to contnue(1/0)?

1
Enter the choice
1
Enter the element: 32
do you wish to contnue(1/0)?
1
Enter the choice
1
Enter the element: 56
do you wish to contnue(1/0)?
1
Enter the choice
3
Elements in queue are23
Elements in queue are32
Elements in queue are56
do you wish to contnue(1/0)?
1
Enter the choice
2
the deleted element is23
do you wish to contnue(1/0)?
1
Enter the choice
2
the deleted element is32
do you wish to contnue(1/0)?
1
Enter the choice
2
the deleted element is56
do you wish to contnue(1/0)?
1
Enter the choice
2
the deleted element is0
java.lang.ArrayIndexOutOfBoundsException: -1the queue is empty
do you wish to contnue(1/0)?