How do you check to see if the 1st letter in a str

问题:

In my if statement, I'm trying to check if the first letter of a string is either Y or y, and then proceed as such. Below is what I have, but I don't believe it to be correct.

System.out.print("Do you wish to do another calculation (Yes/No): ")
      option = scan.next();
         if (option.substring(0,1) == "N" && option.substring(0,1) == "n" )
         {
            System.out.println("Have a good day");
            System.exit(0);
         }
bmi.setOption(option);

I instantiated option as String option = " "; earlier on in my program. I know how to check if strings equal a certain character, however am having trouble checking to see if only the FIRST character of the string is equal to something.

Thank you!

回答1:

if (Character.toLowerCase(option.charAt(0)) == 'n')

回答2:

The first char can't be both "N" and "n", looks like you want it to be "N" or "n"

     if (option.substring(0,1).equals("N") || option.substring(0,1).equals("n") )

We had == before which is more like a memory comparison we want to compare value so we use equals