'function VTable for error: undefined reference to... 'cause and solution of the problem

QT in , Classes should support signal and slot mechanisms , Need to inherit from QObject And add Q_OBJECT macro .
If you use QtCreator Create a class , No choice to inherit from QObject Class or its subclasses , After creation, it is manually modified and inherited from QObject And manually add Q_OBJECT macro , There may be "function vtable for error: undefined reference to … " error .

resolvent : Remove the newly created class file from the project ( Do not delete from disk ), Then add it to the project ,QtCreator This class will be re parsed , The above error will not occur again .