My Java Program is not working

Question

I'm not so good at programming and can't tell why this isn't working. Whatever I input, it always go straight to the else statement.

    public void pizzaIntro()
    {
    Scanner user_input = new Scanner(System.in);
    String user_command = "null";
    String apology = "I'm sorry it appears there has been some kind of mistake in your order.";
    System.out.println("Welcome to " + cM + " here we strive to deliver excellent services to all our customers!");
    System.out.println("The current prize for pizza is $" + bP + " and an extra $" + tP + " per topping.");
    System.out.println(); System.out.println();
    while(user_command != "exit")
    {
        System.out.print("Would you like toppings?(yes/no):");
        user_command = user_input.next();
        if(user_command.toLowerCase() == "yes")
        {
            System.out.println("Good Eat Your Pizza.");
        }
        else if (user_command.toLowerCase() == "no")
        {
            System.out.println("Well Ok Then!");
        }
        else
        {
            System.out.println(apology);
            System.exit(1);
        }
    }
    pic1.show();
}

Thank you very much! I can't believe it was something so simple. — user2147193, Mar 08 '13 at 05:48

score 2 · Accepted Answer · edited May 23 '17 at 12:21

Use equals method to compare strings. To know the difference between == and equals, read https://stackoverflow.com/questions/7311451/difference-between-equals-and-instanceof You will get a clear idea of what to use when.

while(!(user_command.equals("exit")) {
    System.out.print("Would you like toppings?(yes/no):");
    user_command = user_input.next();
    if(user_command.toLowerCase().equals("yes"))
    {
        System.out.println("Good Eat Your Pizza.");
    }
    else if (user_command.toLowerCase().equals("no"))
    {
        System.out.println("Well Ok Then!");
    }
    else
    {
        System.out.println(apology);
        System.exit(1);
    }
}

score 1 · Answer 2 · answered Mar 08 '13 at 05:47

1

Use equals method instead of ==

user_command.toLowerCase().equals("yes")

In Java, == always just compares two references. Its OK to use it for primitive data types. String is not primitive datatype. String is a object. You should use equals method.

In your case you can consider using equalsIgnoreCase method to ignore the Case.

answered Mar 08 '13 at 05:47

Jayamohan

12,734
2
27
41

And, for those of us that don't better, please explain why (that's right, you gotta work for that up-vote ;)) – MadProgrammer Mar 08 '13 at 05:48

score 1 · Answer 3 · answered Mar 08 '13 at 05:50

Use equalsIgnoreCase. It is more safe

public void pizzaIntro()
    {
        Scanner user_input = new Scanner(System.in);
        String user_command = "null";
        String apology = "I'm sorry it appears there has been some kind of mistake in your order.";
        System.out.println("Welcome to " + cM
                           + " here we strive to deliver excellent services to all our customers!");
        System.out.println("The current prize for pizza is $" + bP
                           + " and an extra $" + tP + " per topping.");
        System.out.println();
        System.out.println();
        while (!user_command.equalsIgnoreCase("exit"))
        {
            System.out.print("Would you like toppings?(yes/no):");
            user_command = user_input.next();
            if (user_command.equalsIgnoreCase("yes"))
            {
                System.out.println("Good Eat Your Pizza.");
            }
            else if (user_command.equalsIgnoreCase("no"))
            {
                System.out.println("Well Ok Then!");
            }
            else
            {
                System.out.println(apology);
                System.exit(1);
            }
        }
        pic1.show();
    }

score 1 · Answer 4 · answered Mar 08 '13 at 05:51

Never compare any Java objects with "==" (only primitives like int, long, double, etc.). It should read:

if(user_command.toLowerCase().equals("yes")) {
  ...
}

otherwise you check if the location of the object is the same, not the content.

In this particular example you might just want to use String.equalsIgnoreCase(...) instead.

My Java Program is not working

4 Answers4