//Implementation and operations on Queue using Arrays. import java.util.*; class arrayQueue { protected int Queue[] ; protected int front, rear, size, len; public arrayQueue(int n) { size = n; len = 0; Queue = new int[size]; front = -1; rear = -1; } public boolean isEmpty() { return front == -1; } public boolean isFull() { return front==0 && rear == size -1 ; } public int getSize() { return len ; } public int peek() { if (isEmpty()) throw new NoSuchElementException("Underflow Exception"); return Queue[front]; } public void insert(int i) { if (rear == -1) { front = 0; rear = 0; Queue[rear] = i; } else if (rear + 1 >= size) throw new IndexOutOfBoundsException("Overflow Exception"); else if ( rear + 1 < size) Queue[++rear] = i; len++ ; } public int remove() { if (isEmpty()) throw new NoSuchElementException("Underflow Exception"); else { len-- ; int ele = Queue[front]; if ( front == rear) { front = -1; rear = -1; } else front++; return ele; } } public void display() { System.out.print("\nQueue = "); if (len == 0) { System.out.print("Empty\n"); return ; } for (int i = front; i <= rear; i++) System.out.print(Queue[i]+" "); System.out.println(); } } public class Array_Queue { public static void main(String[] args) { Scanner scan = new Scanner(System.in); System.out.println("Array Queue Test\n"); System.out.println("Enter Size of Integer Queue "); int n = scan.nextInt(); arrayQueue q = new arrayQueue(n); char ch; do{ System.out.println("\nQueue Operations"); System.out.println("1. Insert"); System.out.println("2. Remove"); System.out.println("3. Peek"); System.out.println("4. Check empty"); System.out.println("5. Check full"); System.out.println("6. Size"); System.out.println("7. Exit"); int choice = scan.nextInt(); switch (choice) { case 1 : System.out.println("Enter integer element to insert"); try { q.insert( scan.nextInt() ); } catch(Exception e) { System.out.println("Error : " +e.getMessage()); } break; case 2 : try { System.out.println("Removed Element = "+q.remove()); } catch(Exception e) { System.out.println("Error : " +e.getMessage()); } break; case 3 : try { System.out.println("Peek Element = "+q.peek()); } catch(Exception e) { System.out.println("Error : "+e.getMessage()); } break; case 4 : System.out.println("Empty status = "+q.isEmpty()); break; case 5 : System.out.println("Full status = "+q.isFull()); break; case 6 : System.out.println("Size = "+ q.getSize()); break; case 7: System.exit(0); break; default : System.out.println("Wrong Entry \n "); break; } scan.close(); q.display(); System.out.println("\nDo you want to continue (Type y or n) \n"); ch = scan.next().charAt(0); } while (ch == 'Y'|| ch == 'y'); } }