Outro programa, outro problema

.....
  TrataEdit tratat;
  tratat = new TrataEdit();
  
  btn_somar.addActionListener(tratat);   
  
}
public static void main(String[] args) {
  new Swing15().Monta_Form();

public void actionPerformed (ActionEvent evento){
	
  if (evento.getActionCommand().equals("SOMAR")) 
      n1= Integer.parseInt(numero1.getText());
      n2= Integer.parseInt(numero2.getText());
      soma=n1+n2;
      JOptionPane.showMessageDialog(null, soma);