This is my code:

public boolean displayLoginScreen()
    {
        int choice;
        boolean isStaff = true;
        Scanner input  = new Scanner(System.in);
        System.out.print("****************************************************\n");
        System.out.print("                                                    \n");
        System.out.print("         Grocery Store Management System            \n");
        System.out.print("                                                    \n");
        System.out.print("****************************************************\n");
        System.out.println();
        System.out.print("             Do you want to log in as : \n");
        System.out.print("                   1 = Staff \n");
        System.out.print("                   2 = Customer\n");
        System.out.print("                   3 = Exit\n");
        System.out.println();
        
        try
        {
            do 
            {
                System.out.print("Enter your choice : "); 
                choice = input.nextInt();
                System.out.println(); 
                 
                switch(choice)
                {
                    case 1:
                    {
                        isStaff = staffLogin();
                        
                        if(isStaff)
                            return isStaff;
                        else
                            displayLoginScreen();
                        
                        break;
                    }
                    
                    case 2:
                    {
                        customerLogin();
                        return isStaff = false;
                    }
                    
                    case 3:
                        System.exit(0);
                        break;
                        
                    default:
                        System.out.println("Invalid input. Enter again.");
                        System.out.println();
                }
                
            } while(choice != 3);
        }
            
        catch(InputMismatchException e)
        {
            System.out.println("Invalid input. Enter again.");
            System.out.println();
            displayLoginScreen();
        }
        
        return isStaff;
    }

When i run for the first time and enter 1 for choice and the isStaff is false. And then the displayLoginScreen() will run. But for this second time, my choice == 1 and isStaff is true, however, the return isStaff in case 1 did not function and the program run again the do while loop where it ask me to enter my choice again.

CodePudding user response：

Because when you recursively call displayLoginScreen() (which you probably shouldn't be doing in the first place, recursion is not a replacement for just repeating logic in a loop), the code never does anything with the result. To put it simply, the if block here returns a value, the else block does not:

if (isStaff)
    return isStaff;
else
    displayLoginScreen();

If the intent is to return the result of displayLoginScreen(), return it:

if (isStaff)
    return isStaff;
else
    return displayLoginScreen();