This method cannot throw a checked exception that it claims to. This may cause consumers of the API to incorrectly attempt to handle, or propagate, this exception.


The problem

Java allows methods to declare that they throw checked exceptions even when they don’t. This can lead to call sites being forced to explicitly handle or propagate exceptions which provably can never occur. It may also lead readers of the code to search for possibly throwing paths where none exist.

private static void validateRequest(Request request) throws IOException {
  checkArgument(request.hasFoo(), "foo must be specified");

Response handle(Request request) {
  try {
  } catch (IOException e) { // Required, but unreachable.
    return failedResponse();
  // ...

Including unthrown exceptions can be reasonable where the method is overridable, as overriding methods will not be able to declare that they throw any exceptions not included.


Suppress false positives by adding the suppression annotation @SuppressWarnings("CheckedExceptionNotThrown") to the enclosing element.