Errors & Exceptions

Notch raises failures with throw and handles them with try / catch.

Quick reference

throw 'boom'

try
  throw 'boom'
catch RuntimeException as e
  print(e)
end

Throwing

throw raises a value as an error:

throw 'boom'

Catching

A try block runs its statements; a matching catch handles a thrown exception, binding it to a name with as:

try
  throw 'boom'
catch RuntimeException as e
  print(e)
end

Exception types

Exception types resolve by their short name in throw, catch, and new without an import:

throw IOException("disk gone")

Using an exception type as a plain value elsewhere still needs an import - see Java Interop.

See also

• Error Index for every diagnostic code Notch reports, with a cause and a fix for each. This page covers raising and handling errors in your own code; the index covers the errors Notch itself reports.
• Java Interop for how JVM types resolve, and for null handling.
• Control Flow for the surrounding statement forms.