OutOfMemoryError with Java

Recently had to investigate an OutOfMemoryError issue possibly caused by my Java code.  Some tools/information I have found useful so far are:

1. VisualVM - profiler that you probably already have installed.  Check for <JAVA_HOME>/bin/jvisualvm.exe
   
• If you have problems installing plugins that you need, for example, as above, download and install manually  
• If you encounter a "Cannot connect to service" error, consider attempting with JConsole first by running <JAVA_HOME>/bin/jconsole -debug to determine the reason why;  Troubleshooting connection problems in JConsole
2. Generations - describes Java memory management.  It will help you interpret the graphs in the Visual GC plugin
3. Understanding Weak References - never heard of weak references in the context of Java?  Me too