Switch without break

by

Findbugs is flagging up that falling through from one case to the next is generally not a good idea if there’s any code in the first one (although sometimes it can be used to good effect). So when it sees the second case and no break, it reports the error.

So for instance:

switch (foo) {
    case 0:
        doSomething();
    case 1:
        doSomethingElse();
    default:
        doSomeOtherThing();
}

This is perfectly valid Java, but it probably doesn’t do what the author intended: If foo is 0, all three of the functions doSomething, doSomethingElse, and doSomeOtherThing run (in that order). If foo is 1, only doSomethingElse and doSomeOtherThing run. If foo is any other value, only doSomeOtherThing runs.

In contrast:

switch (foo) {
    case 0:
        doSomething();
        break;
    case 1:
        doSomethingElse();
        break;
    default:
        doSomeOtherThing();
        break;
}

Here, only one of the functions will run, depending on the value of foo.

Since it’s a common coding error to forget the break, tools like Findbugs flag it up for you.

There’s a common use-case where you have multiple case statements in a row with no intervening code:

switch (foo) {
    case 0:
    case 1:
        doSomething();
        break;
    case 2:
        doSomethingElse();
        break;
    default:
        doSomeOtherThing();
        break;
}

There, we want to call doSomething if foo is 0 or 1. Most tools won’t flag this up as a possible coding error, because there’s no code in the case 0 prior to the case 1 and this is a fairly common pattern.

More Related Contents:

  1. Switch statement (Character) [closed]
  2. New to Java and having issues writing and example
  3. Why can’t I use switch statement on a String?
  4. Why do we need break after case statements?
  5. Is it possible to use the instanceof operator in a switch statement?
  6. Turning Sonar off for certain code
  7. Why switch is faster than if
  8. Declaring and initializing variables within Java switches
  9. In a switch statement, why are all the cases being executed?
  10. Test for floating point equality. (FE_FLOATING_POINT_EQUALITY)
  11. Using two values for one switch case statement
  12. Java switch statement multiple cases
  13. Is there a way to ignore a single FindBugs warning?
  14. Java: If vs. Switch
  15. Could not find artifact com.sun:tools:jar:0
  16. Why is default required for a switch on an enum?
  17. switch expression can’t be float, double or boolean
  18. Android coding with switch (String)
  19. Why do I get a “variable might not have been initialized” compiler error in my switch block?
  20. Use string in switch case in java
  21. Java 8, how can I implement a switch statement using streams?
  22. How to use null in switch
  23. How is String in switch statement more efficient than corresponding if-else statement?
  24. Case insensitive matching in Java switch-case statement
  25. Switch over type in java
  26. ResultSet not closed when connection closed?
  27. Why can’t your switch statement data type be long, Java?
  28. If-else working, switch not [duplicate]
  29. Using Integer in Switch Statement
  30. Maximum number of enum elements in Java

Leave a Comment