Will a java exception terminate the whole java application?

Question

I used to think that when an exception happened, the whole java application will be terminated. For example, I write a test function to test my idea.

public void test(){
    File fileDir=new File(sourceDataDir);
    if(fileDir.exists()){
        File[] files = fileDir.listFiles();
        for(int index=0 ; index<files.length ; index++){
            System.out.println("index = "+index);
            File file = files[index];
            if(index == 1)//delete a file to cause a FileNotFoundException
                file.delete();
            try {
                BufferedReader in = new BufferedReader(new FileReader(file));
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }
        }
    }
}

I delete a file to cause a FileNotFoundException manually. I used to think that the whole application will terminate when the exception happened. But in fact, the application will continue reading the remaining files. So, my question is, in what condition an exception will cause the whole application to be terminated?

Answer 1

If an exception is not caught with catch, the thread in which the exception occurred will be terminated. If no non-daemon threads remain the JVM will terminate. That's the only way how an exception might terminate a JVM. If you catch an exception it will never cause a JVM termination.

Answer 2

Here's the deal with exceptions. They are of 2 types : Checked and Unchecked.

The Checked exceptions (all exceptions that are NOT subclasses of RuntimeException) must be handled in a try-catch or the code won't compile, like in the OPs question of FileNotFoundException. It's because of this forced handling that these exceptions usually do not terminate the app unless they are thrown up to the calling methods all the way up to the main() method, where they would stop the thread where they occurred.

The Unchecked exceptions (all exceptions that are subclasses of RuntimeException) need not be handled as these are from programming/data flaws (think divide by zero exception or trying to access a member of a null object etc.). These usually rip through the app and crash the thread they appear on, which could be your program on a single threaded execution.