Too many open files

Recently I faced “Too many open files” exception. But what is this message about? This means that for each HTTP connection we open in a Java application, the operating system will allocate a file descriptor to relate the file to our Java process. Once the JVM finishes with the connection, it releases the descriptor.

Read More

Impersonation in Keycloak

I had to implement user impersonation using Keycloak. I haven’t found any e2e solution so I decided to write short post about how we can achieve that.

Read More

Thoughts about recruitment

In may I faced some non typical situation. My new customer canceled our contract before it started. I was left without any project. Initially I was disappointed and angry about this situation, but it’s no good crying over spilt milk :)

Read More

How to add text over JTable print?

During work on one of my last projects I faced to problem, how to add text over JTable print? I couldn’t find any solution which would suit to my case. After several hours of trying another approaches I found easy way how to add text over JTable print. Let’s see how to do this!

Read More

Caching per request with Spring

Recently, I had to cache some values during processing HTTP request in Spring application. Spring does not offer out of the box solution for this, so I had to write my own request cache.

Read More

String.format - not so obvious

To format numbers in Java we should use String.format method, which arguments are:

  • Locale instance
  • specified string format
  • arguments to format (array of objects)
Read More

How to customize HTTP communication logging with RestTemplate?

Nowadays HTTP communication is very important in enterprise projects. For people who use Spring related technologies an obvious decision is to use RestTemplate for executing HTTP requests. Today, I’m going to describe how to customize HTTP communication logging while using RestTemplate.

Read More

Angular 1.5 - scope data binding

This week the QA reported an issue. It was about not downloading file, when a download button was clicked. We use Angular 1.5 to develop frontend of our application. This was Angular related issue which I will describe for you.

Read More

How to start fast working with JDBC?

Many people, at the beginning of their adventure with software development, are scared how many things and tools they have to learn. This is example how to start fast working with JDBC (for more information please go here). There is no need to install any database engine - we will use simple H2 database.

Read More

Starting blog!

Hello everyone! Thank You for visitng my blog. This is a place, where I would try to describe my daily tricky problems (with solutions) while working with Java, JavaScript, SQL and related technologies.

Read More