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    <p>At least two approaches come to mind, which are usually going to be <strong>combined</strong> depending on what you want <code>foo</code> to do:</p> <h3>1. Catch and rethrow only the relevant exceptions</h3> <p>There are only so many exceptions the code in your main flow can throw (probably mostly <code>SqlException</code>s). So only catch and rethrow those, and declare that you're doing so. More to the point, rethrow only the ones you're not actually handling (in your simplified sample code, you're not handling any, but your real life code is probably more subtle).</p> <p>Mind you, some of the exceptions may be runtime exceptions, and so you may want to combine this with the below.</p> <h3>2. Don't catch the exception at all</h3> <p>Like this:</p> <pre><code>// Signature changes to include any exceptions that really can be thrown public void foo() throws XYZException, ABCException { // A flag indicating that the commit succeeded boolean done = false; begin(); try { // Don't have any `return` statements in here (or if you do, // set `done` to `true` first) ... commit(); done = true; // Commit didn't throw an exception, we're done } finally { // finally clause always happens regardless if (!done) { // We must be processing an exception; rollback try { rollback(); } catch (Exception e) { // quash it (e.g., leave this block empty), we don't want // to mask the real exception by throwing a different one } } } } </code></pre> <p>Naturally your signature needs to include any exceptions that may be thrown in the main flow, but that's what you're trying to do, if I'm understanding you correctly.</p> <p>Again, you may well <strong>combine</strong> these two approaches, because you may want to <em>handle</em> some exceptions and not others.</p>
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    1. UST.J. Crowder
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    1. COI'm no fan on #1 because one can never be really sure which runtime exceptions will be thrown. #2 however, is more what I'm looking for, despite being a bit verbose. It would be convenient if Java had a built-in mechanism to find out whether you got into a finally block normally or via an exception.
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      1. USBart van Heukelom
    2. CO@Bart: Agreed about runtime exceptions, that's why I added that sentence to the end of #1 (should have been there when you read, but you may have been reading a stale page -- in any case, it's there now). Re verbosity: I usually have a function to call for silent rollback, so I don't have to write all that stuff every time. :-)
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    3. COIn this case you will have `foo() throws SQLException`. Is it a good idea to expose `SQLException` to the upper level?
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      1. USPetar Minchev
 

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