Welcome to Geoff Hayward's Weblog

Java WSDL Import Without the .class Files
03 May 2016

It is easy to generate a SOAP client from a WSDL with Java. Java comes with the tool named 'wsimport'. The wsimport tool is part of the Java JDK, found in the JDK bin folder. By default when you run the tool it will create and keep the compiled .class files. If you do not need the .class files just add -Xnocompile to the command.

wsimport http://localhost:8080/demo?wsdl -Xnocompile

Convert an ArrayList to an Array in Java
25 February 2016

A colleague ask me how to convert an ArrayList to an Array in Java. Here was my answer:

List<String> results = new ArrayList<>();
...
results.toArray(new String[results.size()]);

Hope it's helpful. If you know of anymore ways to convert an ArrayList to an Array in Java, leave a comment.

Update: The Java 8 Lambda way: ArrayList to an Array

Blinking an LED with Java on the Intel Edison
05 February 2016

I have been keen to use Java on the Intel Edison since hearing that the Edison supports Java. At the time of writing this, I could not find much information on how to use Java with the Edison. So I decided to try and get a simple LED blink program going. While a blink program is very simple, the hello world of hardware, it thought me the important bits about using the Edison with Java.

Here is the blink program in action:

And here is the blink program's code:

import mraa.Gpio;

public class EdisonTest {

    static {
        try {
            System.loadLibrary("mraajava");
        } catch (UnsatisfiedLinkError e) {
            System.err.println("Native code library failed to load.");
            System.exit(1);
        }
    }

    public static void main(String[] args) throws InterruptedException {
        Gpio gpio = new Gpio(11);
        gpio.dir(Dir.DIR_OUT);
        int state = 1;

        while (true){
            gpio.write(state);
            state = (state==1?0:1); 
            Thread.sleep(1000);
        }
    } 

}

The command to run the program is java -Djava.library.path=/usr/lib/java/ -jar EdisonTest.jar. I used WinSCP to put the EdisonTest.jar and its lib folder into /home/root/ (where I ran the program from).

If you get any problems check that your manifest file includes the lib folder. And that the lib folder includes the mraa.jar. You can download the mraa.jar and UPM jars from Intel.

Sending a 404 with JSF's FacesContext
08 December 2015

Sending a 404 "page not found" response with JSF is easily achieved. In the example below a 404 "page not found" is sent back to the requester if a search on a primary key does not yield a result.

 public Post findPost(Long id) throws IOException {
        Post post =em.find(Post.class, id);
        if (post == null) {
            FacesContext.getCurrentInstance().getExternalContext().responseSendError(HttpServletResponse.SC_NOT_FOUND, "Page not found");
            FacesContext.getCurrentInstance().responseComplete();
        }
        return post;
    }

As can be seen from the example: to send a 404 "page not found" response with JSF you need to get the external context via the 'FacesContext' object. Then using the external context, of the JSF, set the response code. In this case the response code is an error. Finally, It's important to complete the response to halt server side processing.

Edison Board Now Supports Java
26 October 2015

Intel have announced that the Edison board now supports Java. This is good news for Java developers.