Experiential Code Review for java

Experiential Code Review for java

Please refer below scenarios for details of my question
Scenario 1: I implemented a simple XML tag modification logic wherein I
had to update various XML tags. During code review, an experienced java
guy informs that this is a good candidate to use velocity template in
java.
Scenarion 2: I implemented a jdbc module to connect to multiple database,
execute queries and retrieve output. During code review, an experienced
Java guys informs that this is a good candidate to use
AbstractRoutingDataSource interface wherein you can associate key to each
data source and access it accordingly using spring framework.
How do I know that such things already exists in java which I get to know
during code review. Static code review/coverage tools will not provide me
such valuable experiential code review feedback.
I am from C#, VB.net background and now working on java for past 1 year
and I find java to be an excellent programming language with lots of
things already in place. We just need to find what we want to find and
accordingly learn and integrate it.
So, my question is : How do I know such things already exists and how do I
search for such things which I am not aware of?