Add that line in every constructor of your class: this.setOnClickListerner(this);
For example:
public abstract class ChordDiagram extends View implements OnClickListener
{
public ChordDiagram(Context context)
{
super(context);
this.setOnClickListerner(this);
}
@Override
public void onClick(View v)
{
//it's gonna be implemented by its sons
}
}