In this Java tutorial, you’ve learned how to use class field initializers and class initialization blocks to initialize classes, and how to use constructors, object field initializers, and ...

Reference objects aren't just useful when memory is at a premium; ... I described how to use Java’s reference objects, ... instances of the java.lang.ref.ReferenceQueue class.

Finally, profiling objects that make use of java.lang.ref.* references can lead to confusing results (e.g., results that fluctuate between repeated sizeof() calls on the same object).