Java Programs - Solved 2024 ICSE Computer Science Paper

import java.util.Scanner;
class Gmail{
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        System.out.print("Enter the Gmail ID: ");
        String gm = in.nextLine();
        boolean check = true;
        if(!gm.endsWith("@gmail.com"))
            check = false;
        else{
            String first = gm.substring(0, gm.lastIndexOf('@'));
            if(first.length() == 0)
                check = false;
            for(int i = 0; i < first.length(); i++){
                char ch = first.charAt(i);
                if(!Character.isLetterOrDigit(ch)){
                    check = false;
                    break;
                }
            }
        }
        if(check)
            System.out.println("Valid Gmail ID!");
        else
            System.out.println("Invalid Gmail ID.");
    }
}