HashMap in Java

1) Implement HashMap in Java, with the put and get operations

  HashMap can be implemented in Java Using Arrays. Use the same logic that the Out of the Box
  HashMap follows, for resizing, and load factor, when ever the HashMap reaches the size of the
  resize with the load factor a new Array is created, and the previous array contents are copied over
  to the new Array.

 HashMap is Not Synchronized by default. We can synchronize the whole map by using Synchronization, or by using collection.synchronizedmap(map), which synchronizes all the operations on the map. Alternatively We can use the CocurrentHashMap which does not lock the
read operations, rather locks the segments that are being written.



2) HashMap vs LinkedHashMap vs IdentityHashMap


3) HashMap vs ConcurrentHashMap


4) Implement a Cache using LinkedHashMap