Yogesh's Tech Blog

Usually we read following explanation about java.util.WeakHashMap “A hashtable-based Map implementation with weak keys. An entry in a WeakHashMap will automatically be removed when its key is no longer in ordinary use” Unlike java.util.HashMap, WeakHashMap maintain weak reference for the all keys objects and strong reference of value objects. As per features of weak reference, they are more prone to be collection by GC. WeakHashMap runs some kind of unknown services to remove all the entries from collection whose keys are already garbage collected. It means entries in weak hash map may changes over the time. Whenever there  is a need of more memory to your application, GC cycle will execute and its job is to collect all un-referenced objects or weak references. In some cases GC may collected keys of weak hash map as those are a weak references. Once keys are garbage collected , WeakHashMap’s implementation job is to clear all such entries.   See the following program, I...

     Java’s garbage collection system reclaims objects automatically occurring transparently, behind the scenes, without any programmer intervention. It works like this: when no references to an object exist, that object is assumed to be no longer needed, and the memory occupied by the object is released. This recycled memory can then be used for a subsequent allocation. Although it complete transparent to developer, understanding how GC works helps developer to improve efficiency of Java Program. It is also helpful to improve performance of the program. JDK provides many runtime options to analysis GC and analysis your program behavior. Here is the simple java program to understand GC behavior 1: public class GCTest { 2: public GCTest() { 3: } 4: 5: public static void main(String[] args) { 6: int count = 10000; 7: long startTime = System.currentTimeMillis(); 8: System.out.println(" Total Count = " + count...