CODEWITHSUNDEEP
javaencryptionexceptiontry-catch
tom
tom

Reputation: 2357

Exception not being caught by its catch block, then the method throws an exception of another kind

I'm experiencing some strange behavior but maybe I just don't completely understand how exception-handling works. I have the following piece of code:

public String encrypt(String msg, SecretKeySpec key) throws RuntimeException {

    try {

        System.out.println("1");
        cipher.init(Cipher.ENCRYPT_MODE, key);
        System.out.println("2");

        ...

    } catch (InvalidKeyException e) {
        System.out.println("3");
        throw new RuntimeException("invalid key");
    }

}

Upon invoking, the method throws a RuntimeException and the console output is: 1

(The cipher object is an attribute of the class the method is part of and was successfully created using Cipher.getInstance("AES", "BC"). Here is the documentation of the init method where the program fails.)

Upvotes: 1

Views: 1741

Answers (1)

T.J. Crowder
T.J. Crowder

Reputation: 1074248

The symptoms tell us that init is throwing a RuntimeException. Since that isn't an InvalidKeyException, your catch handler doesn't catch it.

Remember that although init is only documented to throw InvalidKeyException, it can also throw any RuntimeException it likes. RuntimeException doesn't have to be declared (or caught); it's an unchecked exception, that's its purpose.

Although you don't have to catch them, you can catch them if you want. Normally that's not good practice (it's normally a RuntimeException for a good reason), but in limited cases catching it can be appropriate.

Upvotes: 3

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