I have added a new jar file - commons-lang.jar in the lib folder.
Jakarta's commons package provides a very common set of utility classes that provide extra functionality for classes in java.lang.
For a general idea of the commons project,refer : http://jakarta.apache.org/commons/components.html
The API for the commons-lang projct can be found here : http://jakarta.apache.org/commons/lang/api/index.html
There are classes like BooleanUtils,StringUtils and host of other utility classes which are extremely simple and trivial to use.The main advantage of using these classes is that they are well tested and promotes reusability of the code.
For example, consider the 'StringUtils' class.
This contains methods like contains(String str, char searchChar) which checks if String contains a search character, handling null.
Do refer to the API for more details on the same.
Maybe i will add some code segmets if i find some methods that are not trivial.Basically all methods in this project are self explainatory and trivial to use but very helpful.