java: how to declare final a variable that is initialized inside a try - catch block?

Question

I have a variable that is not supposed to change its value after it\'s been initialized, so I want to define it as a final variable.

the problem is that the variable

Answer 1

You could handle the Exceptions more accurately. If you get an Exception opening the connection, you don't have to close it in the finally block I guess. If you get an exception after that, in the try block, and handle the exception in a new nested try-catch block you don't need to define the variable outside. Something like:

    try {
        final Connection conn = getConn(prefix);
        try {
            //code using conn
        } catch (Exception e) {

        } finally {
            closeConnection(conn);
        }
    } catch (DbHelperException e) {
        throw new DbHelperException("error opening connection", e);
    }

Answer 2

How about this?

Connection temp = null;
try {
    temp = getConn(prefix);
} catch (Exception e) {
    throw new DbHelperException("error opening connection", e);
} finally {
    closeConnection(conn);
}
final Connection conn = temp;

Answer 3

Can you try assigning it in both the catch and finally blocks? Like so:

Connection connTemp = null;
final Connection conn;
try {
    connTemp = getConn(prefix);
} catch (Exception e) {
    throw new DbHelperException("error opening connection", e);
} finally {
    closeConnection(conn);
}
conn = connTemp;

Answer 4

Why do you want it final? If you want to pass it to an anonymous inner class, you could do:

Connection conn = null;
try {
    conn = getConn(prefix);
    final Connection finalConn = conn;
    // pass it to inner class here
} catch (Exception e) {
    throw new DbHelperException("error opening connection", e);
} finally {
    closeConnection(conn);
}

The only problem (and quite a big one) with this solution is that you close your connection as soon as you leave this block. So unless you declare and call your anon inner class straight away, this pattern isn't going to work.

Either way, I'd probably rephrase the whole thing if I were you, making prefix final instead and delegating connection handling to the anon inner class.