How to Parse JSON to/from Java Object using Jackson Example

In this example You will learn how to parse a  JSON String to Java and  how to convert Java Object to JSON format using Jackson. JSON stands for JavaScript Object notation is a subset of JavaScript object syntax, which allows all JavaScript client to process it without using any external library. Because of its compact size, compared to XML and platform independence nature makes JSON a favorite format for transferring data via HTTP. Though Java doesn't have any inbuilt support to parse JSON response in core library, Java developers are lucky to have couple of good and feature rich JSON processing libraries such as GSON, Jackson and JSON-simple.  Jackson in a high performance, one of the fasted JSON parsing library, which also provides streaming capability. It has no extenal dependency and solely depends on JDK. It is also powerful and provides full binding support for common JDK classes as well as any Java Bean class, e.g. Player in our case. It also provides data binding for Java Collection classes e.g. Map as well Enum.

How to Synchronize HashMap in Java with Example

HashMap is not synchronized, which means you cannot use it on multi-threaded Java program without external synchronization. In another word, if you share one instance of HashMap between multiple threads, each is either adding, removing or updating entries then it's possible that HashMap loss its structure and not behave as expected. If you have read my earlier article about HashMap, you know that during re-sizing its possible that HashMap exposed to multiple threads, may end up in an infinite loop.  In order to avoid this, usually one HashMap instance is used by one thread, sharing of HashMap instance is not allowed, but if you have to share HashMap and there is no option to avoid that, you can always synchronize HashMap in Java. Ofcourse this will affect the performance and probably reduce the speed of HashMap as synchronized method is always slower than non-synchronized one. In this tutorial, we will learn how we can synchornize HashMap in Java.