Do nothing in a case of an enhanced switch

April 7, 2022

I have following enhanced switch case

@Override
public MultivaluedMap<String, String> update(MultivaluedMap<String, String> incomingHeaders,
        MultivaluedMap<String, String> clientOutgoingHeaders) {

    switch (authMethod) {
        case BASIC -> clientOutgoingHeaders.add("Authorization", basicAuth("admin", "admin"));
        case BEARER -> clientOutgoingHeaders.add("Authorization", "Bearer" + " " + getAccessTokenFromKeycloak());
        case SKIP -> System.out.println(); // How can I remove this?
    }
    return clientOutgoingHeaders;
}

where as authMethod is a

enum AuthMethod{
        BASIC,
        BEARER,
        SKIP
    }

If authMethodis SKIP I simply want the code to do nothing. I don’t want to remove the case.

I am aware, that I could work around this problem in other different ways, but I am curious if this works with an enhanced switch.

Also I am aware, that I could just remove the SKIP case. That is simply not what I want, because I want to make clear, that SKIP does nothing in that case.

This is what I have tried

case SKIP -> {};
case SKIP -> ();

How can I do nothing in a case of an enhanced switch statement?

>Solution :

This is so close!

case SKIP -> {};

You just had one extra semicolon! Remove it and it compiles!

case SKIP -> {}

See the syntax for a SwitchRule in the Java Language Specification:

SwitchStatement:
switch ( Expression ) SwitchBlock

SwitchBlock:
{ SwitchRule {SwitchRule} } 
{ {SwitchBlockStatementGroup} {SwitchLabel :} }

SwitchRule:
SwitchLabel -> Expression ; 
SwitchLabel -> Block 
SwitchLabel -> ThrowStatement

Notice how, if it is an expression, like your add calls, you need a semicolon after it. If you use a block, like {}, you should not add a semicolon.