Case insensitive matching in Java switch-case statement

问题

I was wondering if there is a way to perform case insensitive match in java switch case statement. the default implementation is case sensitive. Please see the example below.

public class SwitchCaseTest {

    /**
     * @param args
     */
     public static void main(String[] args) {

        switch ("UPPER") {
            case  "upper" :
                System.out.println("true");
                break;

            default:
                System.out.println("false");
                break;
        }
    }
}

So above statement returns false as output. And i am trying make it work for case-insensitive match like String.equalsIgnoreCase() would do. I tried to convert both the string literal to lower case and then compare. but was unable to do so.

回答1:

If you want to do that: just make sure the input data is in all lowercase, and use lowercase cases...

switch ("UPPER".toLowerCase()) {
case  "upper" :

....

Localization issues

Also, the ages old issue of localization strikes again, and plagues this thing too... For example, in the Turkish Locale, the uppercase counterpart of i is not I, but İ... And in return, the I is not transformed to i, but a "dotless i": ı. Don't underestimate this, it can be a deadly mistake...

回答2:

You try making everything uppercase or lowercase

String str = "something".toUpperCase();
switch(str){
case "UPPER":
}

String str = "something".toLowerCase();
swtich(str){
case "lower":
}

or even better use enum (note this is only possible from Java 7)

enum YourCases {UPPER1, UPPER2} // cases.
YourCases c = YourCases.UPPER1; // you will probably get this value from somewhere
switch(c){
case YourCases.UPPER1: ....
break;
case YourCases.UPPER2: ....
}

回答3:

try

switch ("UPPER".toUpperCase()) {
    case  "UPPER" :

回答4:

To avoid having to use the case expression to verify if it is lowercase or uppercase, I recommend that you use the following:

String value = String.valueOf(userChoice).toUpperCase();

This helps to make the conversion of lowercase to uppercase before doing the evaluation in the switch case.

来源：https://stackoverflow.com/questions/19180797/case-insensitive-matching-in-java-switch-case-statement

标签

java

string

switch-statement

case-sensitive

case-insensitive