What is Garbage Collection and Does Java have destructors?

Garbage collection is the process of looking at heap memory, identifying which objects are in use and which are not, and deleting the unused objects.

Step 1: Marking

Step 2: Normal Deletion

Step 2a: Deletion with Compacting

Why Generational Garbage Collection?

The information learned from the object allocation behavior can be used to enhance the performance of the JVM. Therefore, the heap is broken up into smaller parts or generations. The heap parts are: Young Generation, Old or Tenured Generation, and Permanent Generation

 General Garbage collection process

Link One

Link Two 

Java does not have destructors; but it has finalizers that does a similar job. 

the syntax is

 
public void finalize(){ 

}