Develop Reference

Importing Beat Link Java Library From Maven Central To Eclipse?

This is the first time I have encountered Maven so I don't really know what I'm doing here.
What I'm trying to accomplish is to import the java library Beat Link into my java code using Maven.
Could anyone please provide a simple step by step on how to do this in eclipse?

On maven central you got the maven dependency text -
<dependency>
<groupId>org.deepsymmetry</groupId>
<artifactId>beat-link</artifactId>
<version>0.6.3</version>
</dependency>
Once you create a maven project you should have a pom.xml file.
You need to add this text to the dependencies section of your pom.xml file.
If that doesnt make sense to you, do yourself a favor and read/watch a quick tutorial about using maven on a java project. It's pretty simple once you see how it works.

JavaFXGL how to get the library for java from maven

I am trying to use the javaFXGL library. Which is the java gaming library. I am not sure how to use maven to download the library to eclipse. Does anyone know a step by step way to download this. I need to this get some example code running.

I would be easier to get the help if you add your code in the question along with the problems/errors you are facing. Anyways I would suggest you to first read this and this to understand what is maven and how it works with Eclipse IDE.
After reading the articles you will understand that maven project has pom.xml file which is used for maven settings or you can say for Dependency Management, Build Management, etc.
To add the library you need to add its maven dependency in the pom.xml inside the <dependencies> tag like below:
<!-- https://mvnrepository.com/artifact/com.github.almasb/fxgl -->
<dependency>
<groupId>com.github.almasb</groupId>
<artifactId>fxgl</artifactId>
<version>0.2.9</version>
</dependency>
You can also find other dependencies on www.mvnrepository.com

How to import Processing libraries into Java application

I am calling Processing functions from Java code.
This works fine for the standard Processing classes, but how to you import other Processing libraries; e.g. gicentre?
I've actually got it working by extracting the jar file from the processing library and then manually installing the artifact into the maven project.
Is there a proper way to do it?

Add this dependancy in your maven pom.xml file.
<!-- mvnrepository.com/artifact/org.processing/core -->
<dependency>
<groupId>org.processing</groupId>
<artifactId>core</artifactId>
<version>2.2.1</version>
</dependency>

Sandip's answer will work for the core Processing library (with the caveat that you should use the latest version, not version 2.2.1), but like you've discovered, gicentre doesn't have a maven repository.
You can download the various gicentre libraries from this page. Each of those libraries comes as a .zip file that contains a .jar file.
Now that you have the .jar file, it's just a matter of adding that .jar to your classpath. How you do that depends on how you've set up your project. The simplest way to do it is to use the command line to compile your project, and then you'd use the -cp argument. You've said you're using Maven, so Googling "maven local jar" will lead to a ton of results, including this one: How to add local jar files to a Maven project?
But note that you don't have to use Maven. You could just set the classpath yourself, either via the command line or via your IDE settings. For simple projects, this can be a better option, especially if Maven is giving you trouble.

How to properly use any Java API

I have been trying to use the vget library/api to make my own youtube video downloader. The vget library can be found here: https://github.com/axet/vget
I have downloaded the zip on github and I imported the project into eclipse. However, I am confused to how I am supposed to properly use this API. Should I make a completely new project, and import the classes that I need or do I put my own source files in the project of the api?
I have read other threads concerning this problem. However, they all mention how a api is typically packaged in a JAR file, but in my case it is just files and classes. So I am confused to how I should properly use this api.

The vget project is a maven project. You can see that because it has a pom.xml file in the root folder of the project.
To use it, you don't even need to download the source, because the compiled jar files are already stored in the central maven repository. You can find more information about this here:
http://mvnrepository.com/artifact/com.github.axet/vget/1.1.23
(in general, you can use the http://mvnrepository.com/ site to search whether your library is available on the maven central repository. If it's even a mildly popular library, then chances are that it is)
What you need to do is to make your own project a maven project.
Here's a "5 minutes" starter guide that describes how to do that.
When you've done that, you just add the dependency on vget to your pom.xml file in the <dependencies> section:
<dependency>
<groupId>com.github.axet</groupId>
<artifactId>vget</artifactId>
<version>1.1.23</version>
</dependency>

Since you are making use of a 3rd party software, and not extending it with your own logic, the way to go is to create a new project, which references the 3rd party software.
You then construct your application and make it do whatever you need it to do. When it comes to using logic which is available within the 3rd party logic, you would then simply delegate that call to the 3rd party library.

I have seen on the link you have provided, that this is a maven project. You have to execute a maven package command, or maven install, so that the jar file will be generated.
With this jar follow the Bill's instructions, and add it as external library to your claspath.
When you do this, you will be able to invoke methods of that api.
Let us know if you need some help doing this in eclipse.
If your project is a maven project, you can solve dependencies problems just adding the dependency written on Readme file to your pom file.

The easiest and most automatic way is to use something like maven, ant, or gradle, that will automatically download and put the jars in to your classpath if they are in the central repositories. For example, in the maven configuration file(pom.xml) you can add this to the dependency list:
VGet Maven Repository
These build tools also allow you to add external jars if needed.

If
I would suggest you get familiar with Maven. At the bottom there is a Maven dependency you just have to include into your pom.xml, and then you can use the extension immediately.
Maven is a build platform which organizes your project in a technical way (convention over configuration, e.g. code is in /src/main/java, tests are in /src/test/java). The proper way is it to create a Maven project in Eclipse (you have to install the plugin and download Maven as well) and put the dependency
<dependency>
<groupId>com.github.axet</groupId>
<artifactId>vget</artifactId>
<version>1.1.23</version>
</dependency>
into your <dependencies> inside your pom.xml. After adding it, you project recognizes the additional package automatically.
Nobody tinkers by adding libraries manually. It's actually not professional to work without a build platform like Maven or Gradle.

How to use apache wicket extensions?

I want to use the AjaxFallbackDefaultDataTable in wicket to view my data but these imports are showing error in eclipse :
import org.apache.wicket.extensions.ajax.markup.html.repeater.data.table.AjaxFallbackDefaultDataTable; import org.apache.wicket.extensions.markup.html.repeater.data.grid.ICellPopulator;
import org.apache.wicket.extensions.markup.html.repeater.data.table.AbstractColumn;
import org.apache.wicket.extensions.markup.html.repeater.data.table.IColumn;
import org.apache.wicket.extensions.markup.html.repeater.data.table.PropertyColumn;
I guess I should be downloading an extensions jar file from somewhere but I don't know where at, and the Apache wicket website is vague regarding this point.
I am using eclipse with maven plugin and wicket 1.5RC1

You can get the wicket-extensions library from the maven repository. This site shows assorted versions and allows you to retrieve it by just downloading the jar or by using various build tools including of course maven.
Maven is a good tool for dealing java dependency management, and wicket quickstart is useful for starting wicket projects with a maven setup.

I simply added the following lines to the pom.xml file to add the extensions dependency .
<dependency>
<groupId>org.apache.wicket</groupId>
<artifactId>wicket-extensions</artifactId>
<version>1.5-RC1</version>
</dependency>