Try/Catch Blues
Performance - It may seem like you are doing good putting try/catch blocks all throughout your code, but you are probably being redundant.
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<div class=Section1>
<p class=MsoNormal><span style='font-size:16.0pt;font-family:Arial'>Try/Catch
Blues</span><o:p></o:p></p>
<p class=MsoNormal><span class=GramE><span style='font-size:10.0pt;font-family:
Arial'>Error Checking Gone Horribly Wrong.</span></span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>Technical
Article by Sachin Mehra (<a href="mailto:[email protected]"><i><span
style='color:windowtext;text-decoration:none;text-underline:none'><span
style='mso-field-code:" HYPERLINK \0022mailto\:sachinweb\@hotmail\.com\0022 "'><u><span
style='color:blue'>[email protected]</span></u></span></span></i></a>)</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>It may seem
like you are doing good putting try/catch blocks all throughout your code, but
you are probably being redundant. When you declare a try/catch block in
Java you cause the compiler to create “protected zones” of execution which
require the runtime to do boundary checks and create further processing for the
system. You are not making the program more stable by doing <span
class=GramE>this,</span> you are making it many times slower!</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>If you have
a try/catch block which has only one line of code inside the </span><span
style='font-size:10.0pt;font-family:"Courier New"'>try <span class=GramE>{ …</span>
} </span><span style='font-size:10.0pt;font-family:Arial'>you are
probably being inefficient. </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>Here is an
example of a <b>bad</b> piece of code:</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'> </span><o:p></o:p></p>
<p class=MsoNormal><b><span style='font-size:8.0pt;font-family:Arial'>Example
1a</span></b><span style='font-size:10.0pt;font-family:Arial'>:</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> </span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span class=GramE><b><span
style='font-size:8.0pt;font-family:"Courier New"'>public</span></b></span><span
style='font-size:8.0pt;font-family:"Courier New"'> <span class=SpellE>HashTable</span>
<span class=SpellE>doEvent</span>(Event <span class=SpellE>event</span>) <b>throws</b>
<span class=SpellE>CBException</span> { </span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> Connection <span class=SpellE>conn</span> =
<b>null</b>;</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> <span class=SpellE>EntityClass</span> <span
class=SpellE>entClass</span> = <b>null</b>;</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> <span class=SpellE>ArrayList</span> list =
<b>null</b>;</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><b><span style='font-size:8.0pt;
font-family:"Courier New"'> <span class=GramE>try</span></span></b><span
style='font-size:8.0pt;font-family:"Courier New"'> {</span><o:p></o:p></p>
<p class=MsoNormal style='text-indent:.5in;background:#E6E6E6'><span
class=GramE><b><span style='font-size:8.0pt;font-family:"Courier New"'>try</span></b></span><span
style='font-size:8.0pt;font-family:"Courier New"'> {</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'>
<span class=SpellE><span class=GramE>conn</span></span>
= <span class=SpellE>dataAdapter.getConnection</span>(<span
class=SpellE>DataSource.PRIMARY</span>);</span><o:p></o:p></p>
<p class=MsoNormal style='text-indent:.5in;background:#E6E6E6'><span
style='font-size:8.0pt;font-family:"Courier New"'>}</span><o:p></o:p></p>
<p class=MsoNormal style='text-indent:.5in;background:#E6E6E6'><span
class=GramE><b><span style='font-size:8.0pt;font-family:"Courier
New"'>catch</span></b></span><span
style='font-size:8.0pt;font-family:"Courier New"'> (Exception e) {</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'>
<span class=SpellE><span
class=GramE>System.out.println</span></span><span
class=GramE>(</span>“[<span class=SpellE>SomeClass</span>] An error occurred
obtaining connection: “ + <span class=SpellE>e.getMessage</span>());</span><o:p></o:p></p>
<p class=MsoNormal style='text-indent:.5in;background:#E6E6E6'><span
style='font-size:8.0pt;font-family:"Courier New"'>}</span><o:p></o:p></p>
<p class=MsoNormal style='text-indent:.5in;background:#E6E6E6'><span
class=GramE><b><span style='font-size:8.0pt;font-family:"Courier New"'>try</span></b></span><span
style='font-size:8.0pt;font-family:"Courier New"'> { </span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'>
<span class=SpellE><span class=GramE>entClass</span></span>
= new <span class=SpellE>EntityClass</span>();</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'>
<span class=GramE>list</span> = <span
class=SpellE>entClass.list</span>(<span class=SpellE>conn</span>);</span><o:p></o:p></p>
<p class=MsoNormal style='text-indent:.5in;background:#E6E6E6'><span
style='font-size:8.0pt;font-family:"Courier New"'>}</span><o:p></o:p></p>
<p class=MsoNormal style='text-indent:.5in;background:#E6E6E6'><span
class=GramE><b><span style='font-size:8.0pt;font-family:"Courier
New"'>catch</span></b></span><span
style='font-size:8.0pt;font-family:"Courier New"'> (Exception e)
{ </span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'>
<span class=SpellE><span
class=GramE>System.out.println</span></span><span
class=GramE>(</span>“[<span class=SpellE>SomeClass</span>] An error occurred
obtaining data from the Entity: “ + <span
class=SpellE>e.getMessage</span>());</span><o:p></o:p></p>
<p class=MsoNormal style='text-indent:.5in;background:#E6E6E6'><span
style='font-size:8.0pt;font-family:"Courier New"'>}</span><o:p></o:p></p>
<p class=MsoNormal style='text-indent:.5in;background:#E6E6E6'><span
class=GramE><b><span style='font-size:8.0pt;font-family:"Courier New"'>try</span></b></span><span
style='font-size:8.0pt;font-family:"Courier New"'> {</span><o:p></o:p></p>
<p class=MsoNormal style='text-indent:.5in;background:#E6E6E6'><span
style='font-size:8.0pt;font-family:"Courier New"'>
<span class=SpellE><span class=GramE>result.put</span></span><span class=GramE>(</span>“stuff”,
list);</span><o:p></o:p></p>
<p class=MsoNormal style='text-indent:.5in;background:#E6E6E6'><span
style='font-size:8.0pt;font-family:"Courier New"'>}</span><o:p></o:p></p>
<p class=MsoNormal style='text-indent:.5in;background:#E6E6E6'><span
class=GramE><b><span style='font-size:8.0pt;font-family:"Courier
New"'>catch</span></b></span><span
style='font-size:8.0pt;font-family:"Courier New"'> (Exception e) {</span><o:p></o:p></p>
<p class=MsoNormal style='text-indent:.5in;background:#E6E6E6'><span
style='font-size:8.0pt;font-family:"Courier New"'>
<span class=SpellE><span class=GramE>System.out.println</span></span><span
class=GramE>(</span>“[<span class=SpellE>SomeClass</span>] An error occurred
putting data into <span class=SpellE>HashTable</span>: ” + <span
class=SpellE>e.getMessage</span>());</span><o:p></o:p></p>
<p class=MsoNormal style='text-indent:.5in;background:#E6E6E6'><span
style='font-size:8.0pt;font-family:"Courier New"'>}</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> }</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> <span class=GramE><b>catch</b></span>
(Exception e {</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> <span
class=SpellE><span class=GramE>System.out.println</span></span><span
class=GramE>(</span>“[<span class=SpellE>SomeClass</span>] An error occurred in
the method: “ + <span class=SpellE>e.getMessage</span>());</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> }</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> <span class=GramE><b>finally</b></span> {</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> <span
class=SpellE><span class=GramE>dataAdapter.releaseConnection</span></span><span
class=GramE>(</span><span class=SpellE>conn</span>);</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> }</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'>} </span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>The above
example is a terrible piece of code. It is inherently inefficient,
represents poor error handling (despite the try/catch blocks) and is very ugly
to look at to say the least. For one, doing a boundary check on </span><span
class=SpellE><span class=GramE><span style='font-size:10.0pt;font-family:"Courier
New"'>dataAdapter.getConnection</span></span></span><span
class=GramE><span style='font-size:10.0pt;font-family:"Courier New"'>(</span></span><span
class=SpellE><span style='font-size:10.0pt;font-family:"Courier
New"'>DataSource.PRIMARY</span></span><span
style='font-size:10.0pt;font-family:"Courier New"'>)</span><span
style='font-size:10.0pt;font-family:Arial'> is pointless, why would you create
a unique boundary for this. This represents poor thinking. Consider
the following example of much more “cleaned up code”.</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'> </span><o:p></o:p></p>
<p class=MsoNormal><b><span style='font-size:8.0pt;font-family:Arial'>Example
1b:</span></b><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> </span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span class=GramE><b><span
style='font-size:8.0pt;font-family:"Courier New"'>public</span></b></span><span
style='font-size:8.0pt;font-family:"Courier New"'> <span class=SpellE>HashTable</span>
<span class=SpellE>doEvent</span>(Event <span class=SpellE>event</span>) { </span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> Connection <span class=SpellE>conn</span> =
<b>null</b>;</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> <span class=SpellE>EntityClass</span> <span
class=SpellE>entClass</span> = <b>null</b>;</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> <span class=SpellE>ArrayList</span> list =
<b>null</b>;</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><b><span style='font-size:8.0pt;
font-family:"Courier New"'> <span class=GramE>try</span></span></b><span
style='font-size:8.0pt;font-family:"Courier New"'> {</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> <span
class=SpellE><span class=GramE>conn</span></span> = <span
class=SpellE>dataAdapter.getConnection</span>(<span
class=SpellE>DataSource.PRIMARY</span>);</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> <span
class=SpellE><span class=GramE>entClass</span></span> = new <span
class=SpellE>EntityClass</span>();</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> <span
class=GramE>list</span> = <span class=SpellE>entClass.list</span>(<span
class=SpellE>conn</span>);</span><o:p></o:p></p>
<p class=MsoNormal style='text-indent:.5in;background:#E6E6E6'><span
class=SpellE><span class=GramE><span style='font-size:8.0pt;font-family:"Courier
New"'>result.put</span></span></span><span
class=GramE><span style='font-size:8.0pt;font-family:"Courier New"'>(</span></span><span
style='font-size:8.0pt;font-family:"Courier New"'>“stuff”, list);</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> }</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> <span class=GramE><b>catch</b></span>
(Exception e {</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> <span
class=SpellE><span class=GramE>System.out.println</span></span><span
class=GramE>(</span>“[<span class=SpellE>SomeClass</span>] An error occurred in
the method: “ + <span class=SpellE>e.getMessage</span>());</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> }</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> <span class=GramE><b>finally</b></span> {</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> <span
class=SpellE><span class=GramE>dataAdapter.releaseConnection</span></span><span
class=GramE>(</span><span class=SpellE>conn</span>);</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> }</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> <span class=GramE><b>return</b></span>
result;</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'>} </span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:8.0pt;
font-family:"Courier New"'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier
New"'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>The above
method in <i>Example 1b</i> is just as effective as <i>Example 1a</i> at
handling exceptions, and its execution time is much faster. Think
logically, if for example the </span><span class=SpellE><span class=GramE><span
style='font-size:10.0pt;font-family:"Courier
New"'>dataAdapter.getConnection</span></span></span><span
class=GramE><span style='font-size:10.0pt;font-family:"Courier New"'>(</span></span><span
style='font-size:10.0pt;font-family:"Courier New"'>)</span><span
style='font-size:10.0pt;font-family:Arial'> method fails, the </span><span
style='font-size:10.0pt;font-family:"Courier New"'>Exception</span><span
style='font-size:10.0pt;font-family:Arial'> will still be caught by the one
single catch block. Also, you can generally rely on the message coming
from the </span><span class=SpellE><span style='font-size:10.0pt;font-family:
"Courier New"'>ConnectionPoolManager</span></span><span style='font-size:10.0pt;
font-family:Arial'>, and </span><span class=SpellE><span style='font-size:10.0pt;
font-family:"Courier New"'>DataAdapter</span></span><span style='font-size:
10.0pt;font-family:Arial'> to pass an understandable failure message.
</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'> </span><o:p></o:p></p>
<p class=MsoNormal><span class=GramE><span style='font-size:10.0pt;font-family:
Arial'>Lets</span></span><span style='font-size:10.0pt;font-family:Arial'> take
a look at another bad habit:</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'> </span><o:p></o:p></p>
<p class=MsoNormal><b><span style='font-size:8.0pt;font-family:Arial'>Example
2a:</span></b><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:Arial'> </span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span class=GramE><b><span
style='font-size:10.0pt;font-family:"Courier New"'>try</span></b></span><span
style='font-size:10.0pt;font-family:"Courier New"'> {</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span class=GramE><b>try</b></span>
{</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span class=SpellE><span
class=GramE>compEntity.fetch</span></span><span class=GramE>(</span><span
class=SpellE>conn</span>, <span
class=SpellE>compToolEvent.getComponentId</span>());</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span class=SpellE>ArrayList</span>
roles = <span class=SpellE><span class=GramE>genRolesEntity.list</span></span><span
class=GramE>(</span><span class=SpellE>conn</span>);</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> </span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span class=SpellE><span
class=GramE>results.put</span></span><span class=GramE>(</span>"roles",
roles);</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span class=SpellE><span
class=GramE>results.put</span></span><span class=GramE>(</span>"component",
<span class=SpellE>compEntity</span>);</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> }</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span class=GramE><b>catch</b></span> (<span
class=SpellE>CBException</span> e) {</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span
class=GramE><b>throw</b></span><b>
new</b> <span class=SpellE>CBException</span>(“Error: “ + <span
class=SpellE>e.toString</span>());
</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> }</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span class=GramE><b>catch</b></span>
(Exception e) {</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span
class=GramE><b>throw</b></span><b>
new</b> <span class=SpellE>CBException</span>(“Error: “ + <span
class=SpellE>e.toString</span>());</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> }</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> … Hidden Code Here …</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'>}</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span class=GramE><b><span
style='font-size:10.0pt;font-family:"Courier New"'>catch</span></b></span><span
style='font-size:10.0pt;font-family:"Courier New"'> (Exception e) { </span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span
class=GramE><b>throw</b></span><b>
new</b> <span class=SpellE>CBException</span>(“Error: “ + <span
class=SpellE>e.toString</span>());</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'>}
</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:Arial'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>First of
all, if you don’t see a problem in the above block of code then you don’t
understand Exceptions. The above code shows massive
redundancy in the error handling. Let’s say for example that </span><span
class=SpellE><span class=GramE><span style='font-size:10.0pt;font-family:"Courier
New"'>compEntity.fetch</span></span></span><span
class=GramE><span style='font-size:10.0pt;font-family:"Courier New"'>(</span></span><span
style='font-size:10.0pt;font-family:"Courier New"'>) </span><span
style='font-size:10.0pt;font-family:Arial'>throws a </span><span class=SpellE><span
style='font-size:10.0pt;font-family:"Courier New"'>CBException</span></span><span
style='font-size:10.0pt;font-family:Arial'>, this is what happen at
runtime:</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>1. Line:
</span><span class=SpellE><span class=GramE><span style='font-size:10.0pt;
font-family:"Courier New"'>compEntity.fetch</span></span></span><span
class=GramE><span style='font-size:10.0pt;font-family:"Courier New"'>(</span></span><span
class=SpellE><span style='font-size:10.0pt;font-family:"Courier New"'>conn</span></span><span
style='font-size:10.0pt;font-family:"Courier New"'>, <span
class=SpellE>compToolEvent.getComponentId</span>())
</span><span style='font-size:10.0pt;font-family:Arial'>Throws a </span><span
class=SpellE><span style='font-size:10.0pt;font-family:"Courier
New"'>CBException</span></span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>2. </span><span
class=SpellE><span style='font-size:10.0pt;font-family:"Courier
New"'>CBException</span></span><span
style='font-size:10.0pt;font-family:Arial'> is CAUGHT by first catch block.</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>3. A
NEW </span><span class=SpellE><span style='font-size:10.0pt;font-family:"Courier
New"'>CBException</span></span><span
style='font-size:10.0pt;font-family:Arial'> is THROWN.</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>4. </span><span
class=SpellE><span style='font-size:10.0pt;font-family:"Courier
New"'>CBException</span></span><span
style='font-size:10.0pt;font-family:Arial'> is caught in the Exception catch
block at the bottom.</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>5. A
NEW </span><span class=SpellE><span style='font-size:10.0pt;font-family:"Courier
New"'>CBException</span></span><span
style='font-size:10.0pt;font-family:Arial'> is THROWN.</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>So what’s
the problem you ask? There are three big problems, and they are that:
Three <span class=SpellE>CBExceptions</span> are instantiated instead of
one! But what does it matter? A lot actually, this type of boundary
checking is expensive and foolish. Consider this revised code.</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'> </span><o:p></o:p></p>
<p class=MsoNormal><b><span style='font-size:8.0pt;font-family:Arial'>Example
2b:</span></b><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:Arial'> </span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span class=GramE><b><span
style='font-size:10.0pt;font-family:"Courier New"'>try</span></b></span><span
style='font-size:10.0pt;font-family:"Courier New"'> {</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span class=GramE><b>try</b></span>
{</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span class=SpellE><span
class=GramE>compEntity.fetch</span></span><span class=GramE>(</span><span
class=SpellE>conn</span>, <span
class=SpellE>compToolEvent.getComponentId</span>());</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span class=SpellE>ArrayList</span>
roles = <span class=SpellE><span class=GramE>genRolesEntity.list</span></span><span
class=GramE>(</span><span class=SpellE>conn</span>);</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> </span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span class=SpellE><span
class=GramE>results.put</span></span><span class=GramE>(</span>"roles",
roles);</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span class=SpellE><span
class=GramE>results.put</span></span><span class=GramE>(</span>"component",
<span class=SpellE>compEntity</span>);</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span class=GramE>return</span>
results;</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> }</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span class=GramE><b>catch</b></span> (<span
class=SpellE>CBException</span> e) {</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span
class=GramE><b>throw</b></span><b>
e;</b></span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> }</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span class=GramE><b>catch</b></span>
(Exception e) {</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span
class=GramE><b>throw</b></span><b>
e</b>;</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> }</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> … Hidden Code Here …</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'>}</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span class=GramE><b><span
style='font-size:10.0pt;font-family:"Courier New"'>catch</span></b></span><span
style='font-size:10.0pt;font-family:"Courier New"'> (<span class=SpellE>CBException</span>
e) {</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span class=GramE><b>throw</b></span>
e;</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'>}</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span class=GramE><b><span
style='font-size:10.0pt;font-family:"Courier New"'>catch</span></b></span><span
style='font-size:10.0pt;font-family:"Courier New"'> (Exception e) { </span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span
class=GramE><b>throw</b></span><b>
new</b> <span class=SpellE>CBException</span>(“Error: “ + <span
class=SpellE>e.toString</span>());</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'>}
</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:Arial'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>The above
example makes much more sense. When we catch a </span><span class=SpellE><span
style='font-size:10.0pt;font-family:"Courier New"'>CBException</span></span><span
style='font-size:10.0pt;font-family:Arial'>, we just throw the existing </span><span
class=SpellE><span style='font-size:10.0pt;font-family:"Courier
New"'>CBException</span></span><span
style='font-size:10.0pt;font-family:Arial'> instance which is caught again and
thrown to the higher level. In this case we only create one </span><span
style='font-size:10.0pt;font-family:"Courier New"'>Exception</span><span
style='font-size:10.0pt;font-family:Arial'> object. The above
example is once again also inherently redundant anyways, and can be even
further compressed into the following example (remembering the discussion
earlier):</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'> </span><o:p></o:p></p>
<p class=MsoNormal><b><span style='font-size:8.0pt;font-family:Arial'>Example
2c:</span></b><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:Arial'> </span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span class=GramE><b><span
style='font-size:10.0pt;font-family:"Courier New"'>try</span></b></span><span
style='font-size:10.0pt;font-family:"Courier New"'> {</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span class=SpellE><span
class=GramE>compEntity.fetch</span></span><span
class=GramE>(</span><span class=SpellE>conn</span>, <span
class=SpellE>compToolEvent.getComponentId</span>());</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span class=SpellE>ArrayList</span>
roles = <span class=SpellE><span class=GramE>genRolesEntity.list</span></span><span
class=GramE>(</span><span class=SpellE>conn</span>);</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> </span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span class=SpellE><span
class=GramE>results.put</span></span><span
class=GramE>(</span>"roles", roles);</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span class=SpellE><span
class=GramE>results.put</span></span><span
class=GramE>(</span>"component", <span
class=SpellE>compEntity</span>);</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span class=GramE>return</span>
results;</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> … Hidden Code Here …</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'>}</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span class=GramE><b><span
style='font-size:10.0pt;font-family:"Courier New"'>catch</span></b></span><span
style='font-size:10.0pt;font-family:"Courier New"'> (<span class=SpellE>CBException</span>
e) {</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span class=GramE><b>throw</b></span>
e;</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'>}</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span class=GramE><b><span
style='font-size:10.0pt;font-family:"Courier New"'>catch</span></b></span><span
style='font-size:10.0pt;font-family:"Courier New"'> (Exception e) { </span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span class=GramE><b>throw</b></span><b>
new</b> <span class=SpellE>CBException</span>(“Error: “ + <span
class=SpellE>e.toString</span>());</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:"Courier New"'>}
</span><o:p></o:p></p>
<p class=MsoNormal style='background:#E6E6E6'><span style='font-size:10.0pt;
font-family:Arial'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>That’s more
like it. But it could still be better, but that can wait until a later
article.</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:16.0pt;font-family:Arial'>Final
Words</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Arial'>To
re-iterate, don’t use excessive try/catch blocks. Plan more carefully,
and also take advantage of stacked catches to encapsulate code rather than
creating many protected areas. Performance is a very important.</span><o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
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