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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.

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

package helloworld;

public class Helloworld {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        System.out.println("hello world");
    }
    
}

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
    • You actually do not need to include the extension, helloworld will also work.

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