metodos.java

public JOptionPane validarLetra(java.awt.event.KeyEvent evt) {
        char c = evt.getKeyChar();
        if (Character.isDigit(c)) {
            getToolkit().beep();
            evt.consume();
            JOptionPane.showMessageDialog(rootPane, "Digite sólo letras.");
        }
        return null;
    }

    public JOptionPane validarNumero(java.awt.event.KeyEvent evt) {
        char c = evt.getKeyChar();
        if (Character.isLetter(c)) {
            getToolkit().beep();
            evt.consume();
            JOptionPane.showMessageDialog(rootPane, "Digite sólo números.");
        }
        return null;
    }