The WeakReference class, monitoring memory leak and garbage collection in a Java application

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 Below is a Stack implementation that uses an internal resizeable array structure.  public class MyStack< T > implements Stack< T > { private static final int CAPACITY = 100 ; private Object[] array ; private int pos = 0 ; public MyStack () { this . array = new Object[ CAPACITY ] ; } @Override public void push ( T item) { if ( pos >= array . length / 2 ) { Object[] newArray = new Object[ pos * 2 ] ; System. arraycopy ( array , 0 , newArray , 0 , array . length ) ; array = newArray ; } array [ pos ++] = item ; } @Override public T pop () { if (isEmpty()) { throw new RuntimeException( "empty stack" ) ; } @SuppressWarnings ( "unchecked" ) T item = ( T ) array [ pos - 1 ] ; pos -= 1 ; return item ; } @Override @SuppressWarnings ( "unchecked" ) public T peek...
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Real life TestDrivenDevelopment benefit: Tests as Documentation

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I ve been working on an integration component that listens to LDAP server and notifies applications about changes on LDAP entries. My component searches for LDAP change logs. And a change log has the "targetdn" attribute.

Example:
targetDn:
uid=ND2392,ou=Users,dc=MyCompany

There is a business rule about notification process:
If Organization Unit is “Special Users”, skip the notification for that change.

Example:
targetDn:
uid=ND2392,ou=Special Users,dc=MyCompany
 
This changeLog should be skipped because it is about "Special Users" organization unit.

I am using a regular expression to parse the targetdn.
I isolated the code that does parsing and wrote unit tests for many inputs. Of course I added a unit test for the Business Rule mentioned above.

At a point, I thought my regular expression is not good enough and changed it:

Old regex:
[oO][uU]=[^,]*

New regex:
[oO][uU]=[^,\s]*

I was getting prepared to commit my code to Clearcase but I said:
“Just a minute! Lets run all unit tests first..”

After running all tests, I saw that 1 test failed. The test about the business rule failed!
That failure informed me that changing the regex was not a good idea. IT REMINDED ME ABOUT THE BUSINESS RULE. IT SERVED AS DOCUMENTATION.
I love this kind of documentation that not just sits there but helps :)

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