Hello World

The “Hello World” application is the first application everybody writes when trying a new language or new device. This post shows you how easy it is to develop and execute a “Hello World” application on the JNIOR.

So what is a “Hello World” application? Here is a link to a Wikipedia page that covers that. https://en.wikipedia.org/wiki/%22Hello,_World!%22_program

Basically, we use this demo to show the ease of taking an application from the PC and executing it on the JNIOR.

Step 1: Write the program

You can use your favorite IDE for this. We use the NetBeans IDE from the Apache Foundation

View on GitHub

Step 2: Compile the Program

Compiling the program will take your java file source and compile it into a .class file. All of the .class files in the project are then packages into a .jar file. This is really helpful for most applications and project management.

To compile the application, IDEs will typically have a build menu.  All IDEs are different and you might also need to define a couple options to get the .jar file to get built.

Step 3: Transfer the jar to the JNIOR

Again, there are many options to perform this task. The easiest method is to use the WebUI.

• Open the WebUI for a unit by going to http://<IP ADDRESS> in your browser.
• Next, navigate to the folders tab.  We recommend loading your applications in the /flash folder.  This folder will persist through power outages and when the battery eventually dies.
• You can just drag and drop from your file explorer window in to the /flash files views

Step 4: Execute the program on the JNIOR

You can use the terminal of your choice but, again, we are going to stick with the WebUI, and use the Console Tab.

• Navigate to the Console tab.
• Click on “Start Session”
• Login.  The default credentials are jnior:jnior
• At the prompt, type the filename helloworld.java.

Notice the “hello world” output from the execution of our program.