Map value lazy initialization

Tired of the following pattern?

value = map.get(key); if (value == null) {     // Map value lazy initialization in act     value = /* Init value */;     map.put(key, value); } // Use value

Java2html

Here is the elegant solution from the Java 8:

import java.util.HashMap; import java.util.Map; public class MapInit {   public static void main(String[] args) {     Map<String, String> map = new HashMap<>();     String ret;     // Lambda function is called here as there is no value with "theKey" in the map     // The same newly added value returned by the lambda function is returned      ret = map.computeIfAbsent("theKey", key -> "theValue");     System.out.println(ret);     System.out.println(map);     // Lambda function isn't called here as there is the value with "theKey" in the map     // Instead, the value with "theKey" is acquired from the map and returned     ret = map.computeIfAbsent("theKey", key -> "theValue");     System.out.println(ret);     System.out.println(map);     // The "mapping function" is called here as there is no value with "theInitiatedKey" in the map     // The same newly allocated by the mapping function value is returned      ret = map.computeIfAbsent("theInitiatedKey", MapInit::valueInitiator);     System.out.println(ret);     System.out.println(map);     // The "mapping function" isn't called here as there is the value with "theInitiatedKey" in the map     // Instead, the value with "theInitiatedKey" is acquired from the map and returned     ret = map.computeIfAbsent("theInitiatedKey", MapInit::valueInitiator);     System.out.println(ret);     System.out.println(map);   }      private static String valueInitiator(String key) {     // The function is called if only the value with this key is absent from the map     System.out.println("Initiating 'theInitiatedValue'");     return "theInitiatedValue";   } }

Java2html

The output:

theValue {theKey=theValue} theValue {theKey=theValue} Initiating 'theInitiatedValue' theInitiatedValue {theKey=theValue, theInitiatedKey=theInitiatedValue} theInitiatedValue {theKey=theValue, theInitiatedKey=theInitiatedValue}

Inspired by the StackOverflow's question Java map.get(key) - automatically do put(key) and return if key doesn't exist?. Thanks for the solution to Roger Lindsjö.

HTTP replay tool

I searched through the internet but was not able to find anything around this and it was strange to me. I had an idea to resend full HTTP requests captured by e.g. Fiddler, TcpMon or even designed manually to the same or other host:port destination which is suitable e.g. running configured tasks on Jenkins, provide research to your code deployed on an Java Server such as Tomcat or JBoss, etc...

So I've created such tool and it is a part of the Simple Scheduler - you can download its binary and use couple of jars for this purpose, check the httpReplay.bat for instructions. The HTTP Replay tool description on the original site.
Beside simple single request the tool is able to perform batch simultaneous requests for e.g. load or DoS attack steadiness tests.