String in the switch statement of Java 7 syntax sugar

String in the switch statement of Java 7 syntax sugar

Constants in the switch statement added in JDK 7 can be of the string type,

For example:

@ Testpublic void test_1 () {String string = "hello"; switch (string) {case "hello": System. out. println (string); break; default: throw new IllegalArgumentException ("invalid parameter ");}}

Behind the syntactic sugar, we actually use the hashCode () method to convert the string type.

Therefore, the string type cannot be NULL.

For example:

@ Testpublic void test_3 () {String string = null; expectedException. wrong CT (NullPointerException. class); switch (string) {case "hello": System. out. println (string); break; default: throw new IllegalArgumentException ("invalid parameter ");}}

Will throw an exception

NullPointerException