![]() The result when executing the above code will look like this:Īs you can see, because the value of n variable, in this case, is 1, the case for value 1 will be executed and print “Khanh”. In a switch statement, we may not need to declare the default label, if it is declared then it is not necessary to declare on a certain order! To execute only the code for each value of n variable, we must use the break keyword so that after executing the code, our program will exit the switch statement.Īs you can see, we also have a default label, this label is used to handle cases where the value of this n variable is not in the case where the switch statement has been processed. This means that when compiling source code, the value of each case must be determined, not waiting until the program runs, execute to this switch code, the value of each case will then be determined. The declared value for each case must be COMPILE TIME CONSTANTS. With the new changes, the scoping can now be used in a case level, allowing for cleaner code and some more flexibility.Īll in all, there is some nice quality of life changes coming to switch statements once Java 12 releases, be sure to give them a shot when you can.Here, we use the case label to handle each different value of n variable. Better scopingĭue to fallthrough semantics, so far the scoping of switch statements have been the entire statement, meaning that two entirely separate cases could not use the same variable names. In the majority of circumstances, this means that you have to have a default case, but with enums, you just need to make sure you cover all known cases. If you do end up using a switch as an expression in order to return a value, please note that you must have an exhaustive list of cases which either return a value or raise an exception. Or you can include the value directly after break like so: This removes the need to create a variable specifically for the purpose of returning a set value. In a lot of circumstances switches are used to return specific values depending on the input provided, to support this Java 12 allows switch statements to return values. } Returning values from the switch statement ![]() Or you can use the “Traditional” colon syntax: This has been done to make code both easier to read and easier to understand.Ĭase 1, 2, 4 -> ("Foo") Rather than forcing the fallthrough semantics of switch statements, Java 12 will allow you to list multiple case labels on the same line. This assists in making code easier to read/understand in addition to make switch statements quicker to type. Instead of having to break out of different cases, you can use the new switch label which allows the expression on the right to execute if the label matches. What’s being added? Expression label of ‘case L -> expression ’ Help prepare for instance of Pattern Matching (JEP 305).Allow either “Traditional” or “Simplified” scoping/control flow behavior.Extend switches so they can be a statement or an expression.The goals listed in the JEP ( 325) are the following: What does Java 12 want to do with Switch Expressions? ![]() When Java 12 releases, we’re getting improvements to how switch cases are handled, soon we’ll not be limited to only using the C like the syntax of switch statements. This month we are focusing on Java 12 new features you should know about. In other articles, we looked at improvements to Garbage Collection, Java 12’s JVM Constants API explained in 5 minutes, Java 12 made microbenchmarking easier Java 12 Switch Expressions explained in 5 minutes He enjoys experimenting with different computer systems, D&D, and a variety of PC games. Daniel Warren Daniel is a Java Developer at IDRsolutions and the product manager for FormVu.
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