EmptyRunMethodInThread.qhelp

<!DOCTYPE qhelp PUBLIC
  "-//Semmle//qhelp//EN"
  "qhelp.dtd">
<qhelp>


<overview>
<p>New threads can be defined using one of the following alternatives:</p>

<ul>
    <li>By extending the <code>Thread</code> class and overriding its <code>run</code> method.</li>
    <li>By passing an argument of type <code>Runnable</code> to the constructor of the <code>Thread</code> class.</li>
</ul>

<p>Thread instances that are defined using another approach are likely to have no effect.</p>

</overview>
<recommendation>

<p>To avoid empty thread instances, define new threads using one of the following alternatives:</p>

<ul>
    <li>By extending the <code>Thread</code> class and overriding its <code>run</code> method.</li>
    <li>By passing an argument of type <code>Runnable</code> to the constructor of the 
  <code>Thread</code> class.</li>
</ul>

</recommendation>
<example>

<p>In the following example, class <code>Bad</code> shows the definition of a thread that has no effect.</p>

<sample src="EmptyRunMethodInThread.java" />

<p>In the following example, class <code>GoodWithOverride</code> shows how to extend the 
<code>Thread</code> class and override its <code>run</code> method, and class 
<code>GoodWithRunnable</code> shows how to pass an argument of type <code>Runnable</code> to the 
constructor of the <code>Thread</code> class.

</p><sample src="EmptyRunMethodInThreadGood.java" />

</example>
<references>


<li>
  Java API Specification:
  <a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Thread.html">Thread</a>.
</li>
<li>
  The Java Tutorials:
  <a href="https://docs.oracle.com/javase/tutorial/essential/concurrency/runthread.html">Defining and Starting a Thread</a>.
</li>


</references>
</qhelp>