退出Java程序

Question

I have an assignment to write Health Analyzer Application program in Java. This is the first step:

The user has to enter Man (Upper case or lower), or Woman (Upper case or lower) for gender, or Exit (Upper case or lower) for exiting from the program. If the user inputs a word that is not recognized (NOT Man, Woman or Exit) for gender, then the program displays “Wrong Selection of gender! ”, and exits.

This is what I've been working on. The only thing I'm missing is that it reads "Exit" as "Wrong selection of gender", when it should say "Thank you for using this Application"

System.out.println("------------------------------------------------------------\n" +
                   "        Welcome to Health Analyzer\n" +
                   "------------------------------------------------------------");

// SELECTING GENDER
       Scanner scan = new Scanner(System.in);
System.out.println("\t Select Gender\n" +
"\t Enter \"Man\" to calclate average calorie requirements for man\n" +
"\t Enter \"Woman\" to calclate average calorie requirements for Woman\n" +
"\t Enter \"Exit\" for Exiting the Program\n" +
"Enter the Choice: ");

String gender;  
gender = scan.nextLine().toLowerCase();

String man = "Man"; 
String woman = "Woman"; 
String exit = "Exit"; 

if (! (gender.equals(man)) || (gender.equals(woman))) {
    System.out.println("\t Wrong Selection of gender!");
    System.exit(0); }
else if (gender.equals(exit)) {
    System.out.println("\t\t *** Thank you for using this Application ***");
    System.exit(0);
}

Answer 1

Your logic is a bit reversed here.

As you enter exit - the first if (

if (! (gender.equals(man)) || (gender.equals(woman))) {

) will evalute to true, as it is not woman nor man.

You should probably do it with truthy evaluations.

if (man.equals(gender) || woman.equals(gender)) {
doSomeStuffHere
}
else if (exit.equals(gender)) {
exitProgramHere
}
else { 
printWrongGenderHere
}

Also instead of using equals, use equalsIgnoreCase

Answer 2

Since you are using toLowerCase on input string to convert into lowercase. You should compare the string with lowercase only.

gender = scan.nextLine().toLowerCase();
String man = "man"; 
String woman = "woman"; 
String exit = "exit"; 

Otherwise, you could user equalsIgnoreCase for ignoring case-sensitivity.

if (gender.equals(exit)) {
    System.out.println("\t\t *** Thank you for using this Application ***");
    System.exit(0);
}
else if (! (gender.equals(man) || gender.equals(woman)) ) {
    System.out.println("\t Wrong Selection of gender!");
    System.exit(0); 
}