Blog on pikodat.com

Embracing Innovation: Angular 17's New Features Spotlighting Vite and Standalone Components

Wed, 08 Nov 2023 16:13:27 +0200

The continuous evolution of web development maintains its pace, and Angular, as a frontrunner in this race, is moving forward with exciting updates. With the advent of Angular 17, we are witnessing a leap into a future where development is faster, smoother, and more intuitive, thanks to the introduction of significant new features. As we unpack the latest release, special attention is drawn to the stable integration of Vite and the introduction of Standalone Components—enhancements that are set to redefine the Angular experience.

A Heartwarming Project: Building a Website for My Sons' Former Daycare Provider

Thu, 19 Oct 2023 16:13:27 +0200

As many of you know, my primary focus has always been on app development. It’s my bread and butter, what I live and breathe. But every so often, life throws an unexpected opportunity your way, encouraging you to stretch your wings and try something new. Recently, I had the chance to do just that, and the experience was incredibly fulfilling.

Understanding Java's Long and Integer Cache

Tue, 14 Mar 2023 16:13:27 +0200

Java’s Integer and Long classes have a built-in caching mechanism that helps reduce memory overhead and improve performance. This cache is used when autoboxing primitive types into their corresponding wrapper classes. The Integer cache range is from -128 to 127 by default, while the Long cache has a fixed range from -128 to 127 as well.

Quarkus Test, Postgres & Testcontainers

Thu, 27 Oct 2022 16:13:27 +0200

Yesterday I deleted all of my local Docker images and suddenly my setup with Quarkus and Testcontainers JDBC connection string (jdbc:tc:postgresql:latest:///test) didn’t work anymore.

Code

Caused by: org.flywaydb.core.internal.exception.FlywaySqlException: Unable to obtain connection from database: Acquisition timeout while waiting for new connection
-----------------------------------------------------------------------------------------------
SQL State  : null
Error Code : 0
Message    : Acquisition timeout while waiting for new connection
	at org.flywaydb.core.internal.jdbc.JdbcUtils.openConnection(JdbcUtils.java:60)

It seems that pulling the underlying containers for Postgres and Testcontainers causes this issue because that pulling takes a while. So you could implement a QuarkusTestResourceLifecycleManager and adjust the time:

Install Oracle JDK without the installer on macOS

Fri, 09 Jul 2021 16:13:27 +0200

How to install the Oracle JDK without the installer on macOS and also use it with SDKMAN!

Capacitor and the Ionic Native Shake Plugin

Fri, 31 Jul 2020 16:13:27 +0200

In a client application (Android and iOS) I recently needed the shake gesture. Fortunately, there is an Ionic Native plugin for this. Although only iOS support appears in the documentation, the plugin worked without any problems under Cordova / Capacitor on Android. There were also no problems with the combination of Cordova and iOS. But the combination of Capacitor and iOS did not work. Since the app was already developed with Capacitor and I did not want to give away the advantages of Capacitor, I did some research. And it was easy to find out why it didn’t work. I tried to implement the motionEnded method (which notifies the Shake Plugin) in the CDVViewController.m file because there was no MainViewController.m anymore. That did not work but I luckily remembered that Capacitor 2 uses Swift instead of Objective C. So I only need to override the motionEnded method in CAPBridgeViewController.swift.

Rename fields in MongoDB documents

Wed, 22 May 2019 16:13:27 +0200

Often the structure of domain objects needs to be updated to reflect some recent business case changes in your app. A lot of devs I worked with are not annoyed with different docs and domain objects. But I like to reflect changes in the domain object in the underlying collection documents.

I have a working snippet in my toolbox that worked for years. But as it uses cursors it was painfully slow. Somehow until today I don’t thought about using db.collection.updateMany() and the $rename operator.

Stencil components and Vue

Fri, 14 Sep 2018 16:13:27 +0200

Recently I build some components with Stencil for an Angular project. Unsurprisingly the created components also work well with Vue. There are two steps necessary. Here is the workflow:

First Step: Create your Stencil component

At first create a directory and install Stencils dependencies.

Bash

mkdir stencil-components
cd stencil-components
npm init -y
npm install @stencil/core -S
npm install @stencil/utils -D

Now create your component in Stencil. That is well documented here. Name it my-first-component.tsx

TSLint Warnings instead of Errors in Webstorm

Wed, 07 Mar 2018 16:13:27 +0200

That TSLint rules in Webstorm are displayed as error messages is something that drives me nuts. Today I discovered that one can change that behaviour in Webstorm:

Preferences -> Editor -> Inspections
Select linter (TypeScript->TSLint, or just use the search box with tslint
Change Severity to a desired level like Warning or Weak Warning

Write your own TypeScript definition files

Mon, 01 Aug 2016 16:13:27 +0200

Last Year I wrote a blog post about TypeScript and jQuery. I introduced TSD, a manager for TypeScript definition files. TSD, or Typings as TSD is deprecated now, contains nearly thousand definition files. But what if you want to use your own library or a library that has no definition file yet? You could write it yourself. It’s not that hard. I will show you an really simple example.

I created a new Angular 2.0 Project with the Angular CLI. The Angular team switched to TypeScript so it fits perfectly in this example. I added a JavaScript file with a simple function and a tiny class (or what JavaScript devs call classes ;)).

Setting system properties for WildFly with a properties file

Wed, 11 May 2016 16:13:27 +0200

To set or override system properties without changing WildFly’s configuration there is a CLI parameter -p.

Assuming you have a property file vweber.properties in /dev/veit/wildfly/ with the following content

Code

mightyapplication.property=somevalue

and start your WildFly with

Guavas MultiMap FTW

Thu, 21 Apr 2016 16:13:27 +0200

I often have the need for some kind of “grouped list”. I have a key and a list of values. Usually I do the following:

Java

HashMap<Integer, List<String>> map = new HashMap<>();
while (rs.next()) {
  if (!map.containsKey(rs.getInt(Env.KEY)))
        map.put(rs.getInt(ENV.KEY), new ArrayList<>());

  map.get(rs.getInt(Env.KEY)).add(rs.getString(Env.VALUE));
}

return map;

I saw an alternative some months ago but I could not remember the name of the class. Today @bernhard_joerg showed me Guavas Multimap. And what can I say, it was the missing class ;).

Guava Joiner Class

Fri, 01 Apr 2016 16:13:27 +0200

Although I’m a long time user of Google Guava I discovered the class Joiner just a few days ago. Eventually everybody who’s familiar with Googles Apache Commons alternative have heard about it, but I like to show the usage for those who didn’t know yet.

Given the following list:

Java

List<String> nameList = Lists.newArrayList("Solo", "Kenobi", "Skywalker", "Yoda");
String delimiter = ",";

You usually would do the following to join the items in one string:

Remove "Server" and "X-Powered-By" Response Headers in Wildfly

Fri, 22 Jan 2016 16:13:27 +0200

Wildfly identifies himself in the response headers. To remove this you just have to comment/remove the following lines under the urn:jboss:domain:undertow:2.0 (depend on your WildFly version) subsystem in your standalone.xml

Remote debugging Tomcat applications on Raspberry Pi with IntelliJ

Fri, 01 Jan 2016 16:13:27 +0200

In this post I will show how to remote debug Tomcat applications on a Raspberry Pi with IntelliJ.

Where is my code?

Fri, 27 Nov 2015 16:13:27 +0200

A lib I’ve used often lately is Project Lombok. Lombok fills the gap between Java and some C# syntactic sugar features that makes me slightly jealous ;).

Getter and Setter

Something I liked back in my C# days was the syntax of simple getter and setter without any logic:

public class Person
{
    public string Firstname { get; set; }
    public string Lastname { get; set; }
}

Neat and clean compared to the Java version:

Quick Tip: Remove IntelliJ IDEAs unused directories on OS X

Sat, 07 Nov 2015 16:13:27 +0200

After upgrading IntelliJ the old directories still remain unused. I suggest to delete them.

Cache: ~/Library/Caches/<Tool><Version>

Logs: ~/Library/Logs/<Tool><Version>

Plugins: ~/Library/Application Support/<Tool><Version>

IntelliJIdea (Ultimate) or IdeaIC (Community)

Frontend Logging with JavaFX and Log4j 2

Sun, 11 Oct 2015 16:13:27 +0200

Although I’m developing Java EE applications with HTML5, I sometimes have to build Java SE applications with a Frontend. I’ve used Swing or AWT in the past. But since JavaFX 2.0 get lost of that awful JavaFX Script, JavaFX is my weapon of choice. Recently I wrote a multithreaded applications that needs to inform the user of some working results. I guess I was some kind of blue-eyed when I wrote this “log” function:

Maven Plugin to check for Methods that are not implemented

Wed, 30 Sep 2015 16:13:27 +0200

Recently my former colleague, IBM Champion and also highly regarded friend Oliver Busse wrote a blog post called “Quick-Tip: never forget empty methods anymore”. In summary, it can be stated that Oli throws an UnsupportedOperationException to signalize that a method is not implemented. I see this approach often and there is nothing wrong with that. But I think there are two disadvantages:

In my humble opinion the usage of UnsupportedOperationExceptionto signalize that a method is not yet implemented is some kind of mistreatment. To raise UnsupportedOperationExceptiondoesn’t always means it’s not yet implemented.
Another point is, that I don’t like that the developer doesn’t see any warnings before or while compiling. Imagine your are going to use a library. UnsupportedOperationExceptionis a runtime exception and not a checked exception so you never see your failure until the exception is raised (best in production mode ;)).

So I wrote a tiny maven plugin that introduces the @NotYetImplemented annotation. Methods with that annotation generate warnings while packaging the application.

Tooltip: Unirest - Lightweight HTTP Request Client Libraries

Fri, 11 Sep 2015 16:13:27 +0200

There are a lot of HTTP libraries available in the Java universe like the Apache HttpClient library. Also Java provides the HttpURLConnection class as a standard on-board. They all have in common that I (and thats just my humble opinion ;)) don’t like them really because they feel like a way back in 2001.

So today I stumbled over unirest, a simple and lightweight HTTP request client library for Java ( and also other other languages like Ruby or C#). It’s simple and fluent API reminds me of the way you would do HTTP calls in JavaScript.

Pitfall with "this" in TypeScript

Sun, 30 Aug 2015 16:13:27 +0200

Recently I stumbled accross a strange behaviour with the “this” reference in TypeScript.

TypeScript

class TestClass {
    value:string;

    constructor(value:string) {
        this.value = value;
    }


    doSomething():string {
        return "Value: " + this.value;
    }
}


var objectRef = new TestClass("Simple Param");
var methodRef = objectRef.doSomething;

document.write(objectRef.doSomething())
document.write(" --- ")
document.write(methodRef());

Somehow I expect the output Value: Simple Param --- Value: Simple Param. Instead Value: Simple Param --- Value: undefined is displayed. My humble opinion is that method references always should be bound to an object. But the reasons is clear: TypeScript is a superset of JavaScript and so the semantics on “this” remains unchanged.

Node.js and Postgres

Mon, 10 Aug 2015 23:54:07 +0200

This tutorial shows how to create a simple web server with a tiny REST “API” and a PostgreSQL database. I asume that you have installed the node.js platform and npm.

I’m going to use the node-postgres client to connect to the PostgreSQL database. The installation is easily done with npm.

npm install pg

The table I want to query is very simple.

So I’m going to create a server listen on port 8081 that write a response if a GET request is received. The query to the backend database is in a separate function that connects to the PostgreSQL database and prints the result to the response stream as JSON.

TypeScript and jQuery

Fri, 31 Jul 2015 23:54:07 +0200

If you want to use an existing JavaScript library with TypeScript you need some kind of header file. This file, called definition file, contains type informations about the JavaScript library and enables the TypeScript developer to use the library objects like they where TypeScript objects. You can either write your own (I will write a blog post about that in the near future) or take advantage of TSD, a manager for TypeScript definition files based on the GitHub repository Definitely Typed. Definitely Typed is community driven library for nearly 1000 TypeScript definition files.

Why Java Developers might love TypeScript

Fri, 24 Jul 2015 23:54:07 +0200

I’ve met a lot of Java developers that don’t like JavaScript. Weak typing, inequality of equality, the scope of variables et cetera. I encourage them not to use only plain JavaScript. AngularJS and jQuery for example brings the best out of JavaScript. But I particulary understand their skepticism. The last days I was playing around with TypeScript and it seems I really love it. TypeScript feels like JavaScript made right (and thats no wonder, because it was designed by the guy behind Turbo Pascal, Delphi and C#). TypeScript brings a lot more structure and object oriented goodness, thought under the hood it compiles to JavaScript.

Fun with java.net.URL

Wed, 15 Jul 2015 17:54:07 +0200

I’m writing a little app to check the health status of my server and came accross a confusing feature in java.net.URL. I remembered I struggle with this behaviour when I came from C# to Java. So this might be helpful for Java newbies.

Java

URL url1 = new URL("http://pikodat.com");
URL url2 = new URL("http://blog.pikodat.com");

System.out.println(url1.equals(url2));

The output is:

Plesk, Subdomains and (Wildfly) Docker Images

Mon, 13 Jul 2015 17:54:07 +0200

I’m running a Docker container with Wildfly 9 on my server for testing purposes. The server is managed with Plesk, so setting up the subdomain is really easy. For rewriting the subdomain path to the Docker path (and port) there is still some work necessary:

At first you have to install mod_proxy for the Apache Web Server under “Server” - “Tools and Settings” -> “General Settings” -> “Apache Web Server”. Activate “proxy” and “proxy_http”.
Second go to your subdomains “Web Server Settings” and fill in the following lines under “Additional directives for HTTP” (assuming that your Docker image runs on port 8089):

Syntax Highlightning in Ghost

Sat, 04 Jul 2015 17:54:07 +0200

Dieses Blog läuft auf der Blogging Plattform Ghost. Statt HTML oder einem Rich Editor der HTML erzeugt, werden die Artikel in Markdown geschrieben. Markdown ist eine einfache Auszeichnungssprache, welche sich vor allem in der Welt der Softwareentwickler verbreitet hat. Was mir bei der Kombination Ghost + Markdown gefehlt hat, war eine einfache Methode Syntax Highlightning einzubinden. Doch diese Funktionalität lässt sich ohne großen Aufwand nachrüsten. Es gibt einige Möglichkeiten…ich habe mich für prism.js entschieden. Dabei handelt es sich um eine Javascript Bibliothek die ein Highlightning für sehr viele Sprachen bereitstellt. Folgende Schritte sind notwendig:

Phonegap / Cordova 4.x app with Android Studio 1.x

Fri, 22 May 2015 16:13:27 +0200

I assume that you have a working installation of PhoneGap or Cordova CLI. In this post I use the Cordova CLI which is distributed as an npm package in a ready-to-use format (npm install -g cordova).

At first we have to create the app and at the android platform with the Cordova CLI:

Bash

cordova create MyCordovaApp de.flatphormesmedia MyCordovaApp

Bash

MyCordovaApp\cordova platform add android

Next we have to build the the project for the Android platform. This step is important as it adds the android target to the Cordova project

JPA 2.1 and UUID

Sun, 12 Apr 2015 16:13:27 +0200

Recently I came over to map a table in a Postgres Database that contains a UUID Column. With JPA 2.1 there is a very simple way to map this column to the java.util.UUID-Field in the entity:

At first you need a AttributeConverter:

Java

/**
 * Converter for use with UUID and Postgres
 */
@Converter(autoApply = true)
public class UuidConverter implements AttributeConverter<UUID, UUID> {
    /**
     * Convert entity field to db column value
     *
     * @param attribute field
     * @return UUID of entity
     */
    @Override
    public UUID convertToDatabaseColumn(UUID attribute) {
        return attribute;
    }

    /**
     * Convert db column value to entity field
     *
     * @param dbData column
     * @return UUID of entity
     */
    @Override
    public UUID convertToEntityAttribute(UUID dbData) {
        return dbData;
    }
}

And now just add this Converter to your Entity-Fields with the @Column-Annotation:

Java vs. C#: Inheritance of annotations

Sat, 14 Mar 2015 17:54:07 +0200

Recently a friend and I came over with the idea to blog a series of Java vs. C#. Everything related to this topic you’ll find on the internet is too superficial. We are experienced in both technologies and environments (although my friend is more a .NET guy and my daily bread is Java EE) and could provide a more detailed point of view.

Built-in-annotations in Java are not inherited. I think there is no need for an code example because it’s a fact :). But for your own annotations, there is a way to inherit them with the @Inherited-annotation.

Static Code Blocks

Wed, 04 Feb 2015 17:54:07 +0200

In a presentation that I gave recently, I noticed that some of the participants never heard of static code blocks before. Static code blocks let you execute something at class loading time (assign a value for example). They are like “Class-Constructors”. In this example i created a @Default-Configuration-annotation. Once the Application was loaded, the static code block was looking for the annotation and set the default configuration (a property-file)

The annotation:

Filter Requests with JEE 6 / 7

Thu, 15 Jan 2015 16:13:27 +0200

A tiny but shiny improvement with Java EE 6 was the @WebFilter – Annotation which made the filtering and manipulating of requests very easy: No more com.sun.jersey.spi.container.ContainerResponseFilters entries in the web.xml.

All you have to do is to implements the Filter-Interface and annotate your class:

Java

package com.fpm.playground.internal.filter;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;

@WebFilter("/*")
public class CacheFilter implements Filter {

  @Override
  public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain){
    try {

      // manipulate response

      chain.doFilter(request, response);

    } catch (IOException e) {
      //TODO handle exception

    } catch (ServletException e) {
      //TODO handle exception
    }
  }

  @Override
  public void init(FilterConfig filterConfig) throws ServletException {

  }

  @Override
  public void destroy() {
  }

}

With this solutions it’s very easy to enable CORS in REST-Requests or seperatly cache some resources while others have to refresh every request.