Using || in Cases in a Switch?

问题

So for a college lab for Java Fundamentals I'm having trouble. I have to set up a switch and inside that switch a case. There are 3 options for user input, and each option can be answered with letter. The problem is that this letter is allowed to be capital OR lower case, and the problem is I cant seem to figure out how to set it up so a case will allow either of those.

In the code below..crustType is defined as a char.

Keep in mind this is Java Fundamentals and we're just learning about switches, unfortunately our PPT for this doesn't explain what to do in this situation.

switch (crustType)
  {
     case (crustType == 'H' || crustType == 'h'):
        crust = "Hand-tossed";
        System.out.println("You have selected 'Hand-Tossed' crust for your pizza.");
        break;

     case (crustType == 'T' || crustType == 't'):
        crust = "Thin-crust";
        System.out.println("You have selected 'Thin-Crust' crust for your pizza.");
        break;

     case (crustType == 'D' || crustType == 'd'):
        crust = "Deep-dish";
        System.out.println("You have selected 'Deep-Dish' crust for your pizza.");
        break;

     default:
        crust = "Hand-tossed";
        System.out.println("You have not selected a possible choice so a Hand-tossed crust was selected.");
  }

However I keep getting an error with ||...

97: error: incompatible types
      case (crustType == 'H' || crustType == 'h'):
                             ^   required: char   found:    boolean 
102: error: incompatible types

回答1:

Use:

case 'H':
case 'h':
    ...
    break;
case 'T':
case 't':
    ...
    break;

instead. Since the type of crustType is char, then what goes in cases must be of char type. When you put something like

crustType == 'H'

you will get an error because that expression returns a boolean.

回答2:

It's wrong, Use like below

case 'H' :
case 'h' :
       crust = "Hand-tossed";
        System.out.println("You have selected 'Hand-Tossed' crust for your pizza.");
        break;
// Next set code case

This is how a statement can have multiple case labels

回答3:

or you can use if-else-if statements

if(crustType == 'H' || crustType == 'h'){
        crust = "Hand-tossed";
        System.out.println("You have selected 'Hand-Tossed' crust for your pizza.");
        }

     else if(crustType == 'T' || crustType == 't'){
        crust = "Thin-crust";
        System.out.println("You have selected 'Thin-Crust' crust for your pizza.");
        }

     else if(crustType == 'D' || crustType == 'd'){
        crust = "Deep-dish";
        System.out.println("You have selected 'Deep-Dish' crust for your pizza.");
        }

     else{
        crust = "Hand-tossed";
        System.out.println("You have not selected a possible choice so a Hand-tossed crust 
was selected.");
}

or a String.equalIgnoreCase method in the if .

N.B. i would prefer the other answer .. it is just an alternative :)

来源：https://stackoverflow.com/questions/21520252/using-in-cases-in-a-switch

标签

java

switch-statement