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POWhat is the proper way to handle a NumberFormatException when it is expected?
 

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  1. POWhat is the proper way to handle a NumberFormatException when it is expected?
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    <p>I'm running into this situation where I need to parse a <code>String</code> into an <code>int</code> and I don't know what to do with the <code>NumberFormatException</code>. The compiler doesn't complain when I don't catch it, but I just want to make sure that I'm handling this situation properly.</p> <pre><code>private int getCurrentPieceAsInt() { int i = 0; try { i = Integer.parseInt(this.getCurrentPiece()); } catch (NumberFormatException e) { i = 0; } return i; } </code></pre> <p>I want to just simplify my code like this. The compiler doesn't have a problem with it, but the thread dies on the <code>NumberFormatException</code>.</p> <pre><code>private int getCurrentPieceAsInt() { int i = 0; i = Integer.parseInt(this.getCurrentPiece()); return i; } </code></pre> <p>Google CodePro wants me to log the exception in some way, and I agree that this is best practice.</p> <pre><code>private int getCurrentPieceAsInt() { int i = 0; try { i = Integer.parseInt(this.getCurrentPiece()); } catch (NumberFormatException e) { i = 0; e.printStackTrace(); } return i; } </code></pre> <p>I want this method to return <code>0</code> when the current piece is not a number or cannot be parsed. When I don't catch the <code>NumberFormatException</code> explicitly, does it not assign the variable <code>i</code>? Or is there some default value that <code>Integer.parseInt()</code> returns?</p> <p>General style says that if I catch an exception, I should log it somewhere. I don't want to log it. It's normal operation for this exception to be thrown sometimes, which also doesn't sit well with me. I cannot find a function, however, which will tell me if <code>Integer.parseInt()</code> will throw an exception. So my only course of action seems to be to just call it and catch the exception.</p> <p>The <a href="http://download.oracle.com/javase/6/docs/api/java/lang/Integer.html#parseInt(java.lang.String)" rel="noreferrer">javadoc</a> for <code>parseInt</code> doesn't help much.</p> <p>Here are the specific questions I'd like to know:</p> <ul> <li>Is there a method that I can call that will tell me if <code>Integer.parseInt()</code> will throw a <code>NumberFormatException</code> before calling it? Then I would have no problem logging this, since it should never happen.</li> <li>If I simply do not catch the exception, will the valiable not get assigned? Then I will simply initialize it to the value that I want when it's not a number and not catch the exception.</li> <li>Is there a way to mark the exception somehow explicitly that I don't care about it? I'm thinking this would be something similar to <code>AWTEvent.consume()</code>. If so, then I will do this so that Google CodePro doesn't see this as "unlogged".</li> </ul>
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    1. CO"If I simply do not catch the exception, will the valiable not get assigned? Then I will simply not catch the exception." - if you're unsure about whether this is a viable option, I suggest you try it (and walkthrough with a debugger) to be 100% sure you understand what happens in this case. I don't mean to sound like I'm talking down, but I feel that having a solid understanding of exceptions is important.
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    2. COI'm not a Java programmer but in C#, Integer has a TryParse() method which tries the parse the int and returns a bool on whether it was successful. Surely thats better than expecting an exception.
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    3. COI would love it if there was a `tryParse()` method. I think I understand why there's not one, since it basically means doing the work twice. Also, when I try it, the uncaught `NumberFormatException` kills the thread on the spot. I updated the question to reflect this.
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