Jan Daermann

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since Dec 10, 2015
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MySQL Database Spring Tomcat Server
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Recent posts by Jan Daermann

1. I would not worry about the compile time issue, that’s a non issue if you start your own project.
2. If you are worried about the relevance of the tools for your job search, go on stackoverflow in the job section and check what is required. I would think that many jobs require experience with an IDE environment, a backend environment (Java Spring 5.0 or Java Spring Boot 2.0, very similar) and a front end environment (html, css, Javascript plus JS libraries like React or Angular).
3. There are tutorials available: udemy offers a course “fullstack development with Spring Boot 2 and React” for $12.- in the moment. There is also a good book with the same name on Amazon that gives a fun overview without going into too much detail.
4. Just to make sure we are on the same page: Backend means any Java framework (like Spring Boot 2.0), typically edited on an IDE like eclipse. It handles all the data persistence (JPA, Hibernate), security, backend logic and deals with requests that reach the server. It runs on a separate server and typically has access to a database server as well. Nowadays it is often a RESTServer or RESTApi -> it does not return a webpage anymore, it returns a dataset (JSON object, representational state transfer). Frontend often means html, css, Javascript sites, often edited in a different IDE (Visual Studio Code) that typically runs in conjunction with a JS development tool like “npm” or “yarn” (The JS world is a little more complicated here). React and Angular are the graphics libraries for JS that make things easier. npm includes its own webserver that runs the websites simultanously, so you see changes in your code on the flight. The frontend consumes the JSON object coming from the backend and display it. After you have digested this jungle you are a fullstack developer .
2 weeks ago
Eclipse for JavaEE Developers includes JUnit testing. This is probably the version you want to download anyway if you do web applications. Maven and Github support should be included as well.
As for recommendations for Youtube tutorials you would have to post what framework you are planning to use or has been used in the existing project. Spring MVC or Spring RestAPI projects are very different than projects with other frameworks, but they are all Java frameworks.
If you want to improve Modularity in your project I suggest you look for "Java Microservices" on Youtube. If you look for Java Modularity you end up with lessons about Java9+ in the 'SE' world and not so much in the 'EE'/'Jakarta' world.
2 weeks ago
Bucky has a refreshing way to teach his coding - may people have learned from it. It does not go very deep, but it explains the basics. You will outgrow it rather fast.
The tutorials are not up to date anymore, you will not get updated on recent changes in Java. The channel is not maintained anymore for 3 years now. Bucky went on as a programmer in LA and now programs in NYC.
3 weeks ago
Postman has its advantages and it is free. Postman shows you what goes wrong and you don't have to write any website logic to test the REST API.
If you are looking for an up to date quick overview of "how-to": I liked this book: https://www.amazon.com/gp/product/1789138086/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
2 months ago
Usually you can start the projects inside your IDE if you have installed the web server (usually Tomcat) with the project. If you created the project in Spring Boot it should have taken care of that for you. Testing a REST API is then usually done with a program like Postman. You send a request and it returns a dataset - typically a JSON dataset. There will be post requests for login and get requests for data transfer.

The post you reference is from 2014. A lot of things have changed since 2014 in the REST API world.
2 months ago
Hibernate chokes because it cannot find out the strategy to define a unique ID. I suggest you add a line underneath as

You also have to define the Columns, otherwise you end up with a table of unique ID’s and that’s it.
2 months ago
Google Java Style Repository

... and no, it is not a dependency that you can add to your Spring project. Are you maybe looking for the Google @material-ui package to add components to your webpages?
2 months ago
There are multiple ways for DI. This one is specific to JavaFX Controllers and only one of multiple solutions. The only new thing is that you have to wrap your head around the fact that there is only one instance of the FxController that works with the corresponding fxml file -> the one that the fxml file (really:FXMLLoader) instantiated for itself.

Let's assume you have classes FxControllerOne (for FXML1.fxml) and FxControllerTwo (for FXML2.fxml). Let's assume you have info from FXML2.fxml that you read out in its Controller FxControllerTwo and you want to transfer that to FxControllerOne in order to get it onto FXML1.fxml:

1. Create a reference for FxControllerOne in class FxControllerTwo:
FxControllerOne FxC1;

2.Create a method in class FxControllerTwo:
public static void injectFxControllerOne(FxControllerOne fxc1){this.FxC1 = fxc1};

3. In the @FXML private void initialize() method in class FXControllerOne add the line

Now you should be good to call any method of FxControllerOne inside of FxControllerTwo with the following:

'hope that helps (More than it confuses).
2 months ago
Ok, first let’s mention that this is more an academic exercise because access control is usually done with Spring Security Framework and Filters.

You have your logic incorrect. You return the requested data independent from any check whether username and password are valid. Check the post request for server:port/project/login : you return the requested page independent from any test. There should be a test and if it fails you should return the login page and if it passes you should return the student list.
2 months ago
@FXML GridPane gp is null because:
1. GridPane with fx:id = gp is in ESP_Button.fxml
2. associated controller class for ESP_Button.fxml is ButtonController
3. When ConfigurationController initializes it cannot find an associated GridPane and ignores
4. you have to take the 2 controller classes and inject the dependencies between those. Then you can work inside ConfigurationCOntroller with something like myInjectedButtonController.getGridPane().add(stuff)
2 months ago
You need to create a second collection. the first collection contains your items (materials) incl. id, price, etc. The second collection (sale) is a collection of items being sold in one sales process. It will contain other information like quantity per item, tax, rebates - things that are specific to the sale itself.
3 months ago
sysout circleGrid[1][0] and check what’s in there.
your controller should be hooked up correctly. You can check that in the fxml file, you should find something like fx:controller=.....
3 months ago
You have to make the Tableview editable and override the cell with a Datepicker. There are solutions to this:
here and
7 months ago
Your method “Function(){}” (methods start with lower case letters and the wording is very unfortunate) returns one answerArray instance and it is the last case fulfilling the condition in the 3x loop. If you want all answerArrays that fulfil the condition you have to create a collection of answerArrays, add each answerArray to that collection and return that collection. If you print you just have to loop over the collection.
7 months ago