SeatNotAvailableException

 MAIN.JAVA:

import java.util.Scanner;
import java.io.*;
public class Main {
    public static void main(String args[])throws SeatNotAvailableException {
Scanner sc = new Scanner(System.in);
System.out.println("Enter the number of rows and columns of the show:");
int n = sc.nextInt();
int size = (n*n);
int s;
int a[] = new int[size];
int mat[][] = new int[n][n];
System.out.println("Enter the number of seats  to be booked:");
int seats = sc.nextInt();
try {
    for(int i=0;i<seats;i++) {
        System.out.println("Enter the seat number "+(i+1));
        s = sc.nextInt();
        if(a[s]==0) {
            a[s] =1;
            int t=0;
            for(int j=0;j<n;j++) {
            for(int k=0;k<n;k++) {
                mat[j][k] = a[t];
                t++;
            }
            }    
        }else {
            throw new SeatNotAvailableException("Already Booked");
        }
    }
}catch(Exception e) {
    System.out.println(e);
}
finally {
    System.out.println("The seats booked are:");
    for(int i=0;i<n;i++) {
    for(int j=0;j<n;j++) {
        System.out.println(mat[i][j]+"");
    }
    System.out.println();
}
    }
    }
}

SeatNotAvailableException.JAVA:

import java.util.*;
public class SeatNotAvailableException extends Exception{

	public SeatNotAvailableException(String s) {
		super(s);
		// TODO Auto-generated constructor stub
	}
	   
}