Question

If I have a function with a try/finally section, and the thread running it is interrupted while in the try block, will the finally block execute before the interruption actually occurs?

Answer 1

According to the Java Tutorials, “if the thread executing the try or catch code is interrupted or killed, the finally block may not execute even though the application as a whole continues.”

Here’s the full passage:

The finally block always executes when the try block exits. This
ensures that the finally block is executed even if an unexpected
exception occurs. But finally is useful for more than just exception
handling — it allows the programmer to avoid having cleanup code
accidentally bypassed by a return, continue, or break. Putting cleanup
code in a finally block is always a good practice, even when no
exceptions are anticipated.

Note: If the JVM exits while the try or catch code is being executed, then
the finally block may not execute. Likewise, if the thread executing
the try or catch code is interrupted or killed, the finally block may
not execute even though the application as a whole continues.

class Thread1 implements Runnable {

    @Override
    public void run() {
        try {
            Thread.sleep(10000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            System.out.println("finally executed");
        }
    }
}

…

t1.start();
t1.interrupt();

It prints – finally executed