Java Try Catch Finally blocks without Catch

Question

I'm reviewing some new code. The program has a try and a finally block only. Since the catch block is excluded, how does the try block work if it encounters an exception or anything throwable? Does it just go directly to the finally block?

Answer 1

A small note on try/finally: The finally will always execute unless

• System.exit() is called.
• The JVM crashes.
• The try{} block never ends (e.g. endless loop).

Answer 2

Java versions before version 7 allow for these three combinations of try-catch-finally...

try - catch
try - catch - finally
try - finally

finally block will be always executed no matter of what's going on in the try or/and catch block. so if there is no catch block, the exception won't be handled here.

However, you will still need an exception handler somewhere in your code - unless you want your application to crash completely of course. It depends on the architecture of your application exactly where that handler is.

• Java try block must be followed by either catch or finally block.
• For each try block there can be zero or more catch blocks, but only one finally block.
• The finally block will not be executed if program exits(either by calling System.exit() or by causing a fatal error that causes the process to abort).

Answer 3

The Java Language Specification⁽¹⁾ describes how try-catch-finally is executed. Having no catch is equivalent to not having a catch able to catch the given Throwable.

• If execution of the try block completes abruptly because of a throw of a value V, then there is a choice:
  • If the run-time type of V is assignable to the parameter of any catch clause of the try statement, then …
    …
  • If the run-time type of V is not assignable to the parameter of any catch clause of the try statement, then the finally block is executed. Then there is a choice:
    • If the finally block completes normally, then the try statement completes abruptly because of a throw of the value V.
    • If the finally block completes abruptly for reason S, then the try statement completes abruptly for reason S (and the throw of value V is discarded and forgotten).

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(1) Execution of try-catch-finally