Editing Balking pattern (section)

==Implementation==
Below is a general, simple example for an implementation of the balking pattern.<ref name=Grand>{{cite book| last = Grand | first = Mark| title = Patterns in Java, Volume 1: A Catalog of Reusable Design Patterns Illustrated with UML, Second Edition| year = 2002| publisher = John Wiley & Sons| location = Indianapolis, Ind}}</ref> As demonstrated by the definition above, notice how the "synchronized" line is utilized. If there are multiple calls to the job method, only one will proceed while the other calls will return with nothing. Another thing to note is the <code>jobCompleted()</code> method. The reason it is synchronized is because the only way to guarantee another thread will see a change to a field is to synchronize all access to it. Actually, since it is a boolean variable, it could be left not explicitly synchronized, only declared volatile - to guarantee that the other thread will not read an obsolete cached value.

<syntaxhighlight lang="java">
public class Example {
    private boolean jobInProgress = false;

    public void job() {
        synchronized(this) {
            if (jobInProgress) {
                return;
            }
            jobInProgress = true;
        }
        // Code to execute job goes here
        // ...
        jobCompleted();
    }

    void jobCompleted() {
        synchronized(this) {
            jobInProgress = false;
        }
    }
}
</syntaxhighlight>