Question

Cant get this to loop properly. Any tips out there?

import java.util.Scanner;
public class Lab4 {
public static void main(String[] args) {

//Declared variables
int choice;int number; int sum=0; int fact =1;
Scanner scan = new Scanner(System.in);

do {
System.out.println("Please choose one option from the following menu:");
System.out.println("1) Calculate the sum of integers from 1 to m");
System.out.println("2) Calculate the factorial of a given number");
System.out.println("3) Display the leftmost digit of a given number");
System.out.println("4) Quit");
choice= scan.nextInt();

//Based on choice, the entered menun options will be executed
switch(choice){

case 1:
System.out.println("enter a number");
number = scan.nextInt();
for(int i =1; i<=number; i++) {
sum = sum + i;
}
System.out.println("the sum of 1 to " + "" + number + " " + "is" + " " + sum );
number = scan.nextInt();
break;

case 2:
System.out.println("enter a number");
number = scan.nextInt();
for(int i=1; i<=number; i++) {
fact = fact * i;
}System.out.println("The factorial is" + " " + fact);
number = scan.nextInt();
break;
  
case 3:
System.out.println("Enter Number");
number = scan.nextInt();
while(number >= 10)
number = number / 10;
System.out.println("The left most digit is" + " " + number);
number = scan.nextInt();
break;

default:
System.out.println("Invalid choice.");
number = scan.nextInt();
break;
}

}while(choice!=4); {

}
}
}

Answer 1

/*
 *  Java program - menu based operation
 */

import java.util.Scanner;

public class Main
{
  public static void main(String[] args) {

    //Declared variables
    int choice;int number; int sum=0; int fact =1;
    Scanner scan = new Scanner(System.in);

    do
    {
      System.out.println("Please choose one option from the following menu:");
      System.out.println("1) Calculate the sum of integers from 1 to m");
      System.out.println("2) Calculate the factorial of a given number");
      System.out.println("3) Display the leftmost digit of a given number");
      System.out.println("4) Quit");
      System.out.print("Enter choice: ");
      choice = scan.nextInt();

      //Based on choice, the entered menun options will be executed
      switch(choice)
      {
        case 1:
          System.out.print("\nEnter a number: ");
          number = scan.nextInt();
          for(int i =1; i<=number; i++)
          {
            sum = sum + i;
          }
          System.out.println("The sum of 1 to " + "" + number + " " + "is" + " " + sum );
          break;

        case 2:
          System.out.print("\nEnter a number: ");
          number = scan.nextInt();
          for(int i=1; i<=number; i++)
          {
            fact = fact * i;
          }
          System.out.println("The factorial is" + " " + fact);
          break;
          
        case 3:
          System.out.print("\nEnter Number: ");
          number = scan.nextInt();
          while(number >= 10)
            number = number / 10;
          System.out.println("The left most digit is" + " " + number);
          break;
        
        case 4:
          System.exit(1);

        default:
          System.out.println("Invalid choice.");
          break;
      }

      System.out.print("\nDo you want to continue? (1/0): ");
      choice = scan.nextInt();
      System.out.println();
    
    } while(choice == 1);

    scan.close();

  }
}

/*  Program ends here */