org.sonar.l10n.java.rules.java.S128.html Maven / Gradle / Ivy

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Why is this an issue?
When the execution is not explicitly terminated at the end of a switch case, it continues to execute the statements of the following case. While
this is sometimes intentional, it often is a mistake which leads to unexpected behavior.
Noncompliant code example
switch (myVariable) {
  case 1:
    foo();
    break;
  case 2:  // Both 'doSomething()' and 'doSomethingElse()' will be executed. Is it on purpose ?
    doSomething();
  default:
    doSomethingElse();
    break;
}

Compliant solution
switch (myVariable) {
  case 1:
    foo();
    break;
  case 2:
    doSomething();
    break;
  default:
    doSomethingElse();
    break;
}

Exceptions
This rule is relaxed in the following cases:
switch (myVariable) {
  case 0:                                // Empty case used to specify the same behavior for a group of cases.
  case 1:
    doSomething();
    break;
  case 2:                                // Use of a fallthrough comment
    // fallthrough
  case 3:                                // Use of return statement
    return;
  case 4:                                // Use of throw statement
    throw new IllegalStateException();
  case 5:                                // Use of continue statement
    continue;
  default:                               // For the last case, use of break statement is optional
    doSomethingElse();
}

Resources

   MITRE, CWE-484 - Omitted Break Statement in Switch 
   CERT, MSC17-C. - Finish every set of statements associated with a case label with a
  break statement 
   CERT, MSC52-J. - Finish every set of statements associated with a case label with a
  break statement