program is compiling even without implementing the interface
<p>I have an interface named <code>abc</code></p>

<pre><code>public interface abc
{
    void start();
}
</code></pre>

<p>and I have an abstract class named <code>def</code> </p>

<pre><code>public abstract class def extends Thread implements abc
{
}
</code></pre>

<p>I created another class that extends <code>def</code> called <code>ghj</code></p>

<pre><code>public class ghj extends def
{
  //it is defing all the methods of its above abstract class
  //now it does not implement the method define in interface start();
}
</code></pre>

<p>Please advise if the  class <code>ghj</code> does not implement the interface <code>abc</code> required methods then how can the program be compiling? </p>
