[Java 8] Map.computeIfAbsent()

The computeIfAbsent method is similar to compute(), however it only has side effects on the map if the key wasn’t there before applying the method. One important thing is that the signature takes a Function as an argument and not a BiFunction as in the case of compute().

Here’s an example:


[Java 8] Map.compute example

Here’s a Java 8 Map.compute() example. Basically this construct replaces an idiom such as:

It does an in-place transformation by using a BiFunction, therefore you need to return if you have more than one statement. Another important thing about compute: If the BiFunction returns null and the key was in the map, it is…

[JAX-RS] Access-Control-Allow-Origin as a Filter

So if you’re getting the Access-Control-Allow-Origin error in chrome. Then you need to be sending those headers with the response from the server. One solution would be to put it in the Response in each method. A better (and more scalable) solution is to use a filter. Then don’t forget to disable it in production.

Netbeans ugly fonts

If the fonts “cut your eyes” in Netbeans then: Open netbeans.conf under ${netbeans-home}/etc/ In the netbeans_default_options= section append at the end:

and restart netbeans.

[Java Concurrency] An example of AtomicInteger

Here’s a simple example that shows how AtomicInteger can be used instead of the not thread-safe int Counter implementation.  


[JAVA 8] Custom DTO mapping

Very nice idea: http://www.idanfridman.com/mapping-your-entities-to-dtos-using-java-8-lambda-expressions/ Mapping your Entities to DTO’s Using Java 8 Lambda expressions We all facing the cluttered overhead code when we need to convert our DTO’S to Entities(Hibernate Entities, etc..) and backwards. In my example ill demonstrate how the code getting much shorter with Java 8. Let’s create the Target DTO:


Java CyclicBarrier example

An example from the very good Java 8 book “Beginning Java 8 Language Features”. :


[Security issue!] BackupWordPress Plugin has a security issue!

The BackupWordpress plugin has a very very serious security issue! https://wordpress.org/plugins/backupwordpress/ So if you installed it and set it up to backup your database regularly. The plugin, by default, will place your backups under the wp-content folder which is web accessible! For example, after a couple of days, I’ve found my backups under this folder:…

[Java] util.concurrent.Semaphore example

An example from the very good Java 8 book “Beginning Java 8 Language Features”. :