[SOLUCIONADO] Cambiar color de un TextArea desde otra ventana

[mendez46]

Es decir tengo un JTextArea en una ventana y en otra tengo 3 botones con el texto azul , negro , y gris. Y quiero que según le dé a un botón cambie el color del JTextArea que está en la otra ventana. Me da un error del tipo:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at academia.TAcolor.JBnegroActionPerformed(TAcolor.ja va:74)
at academia.TAcolor.access$000(TAcolor.java:13)
at academia.TAcolor$1.actionPerformed(TAcolor.java:50 )
at javax.swing.AbstractButton.fireActionPerformed(Abs tractButton.java:2022)
at javax.swing.AbstractButton$Handler.actionPerformed (AbstractButton.java:2348)
at javax.swing.DefaultButtonModel.fireActionPerformed (DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultB uttonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseRe leased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.jav a:6535)
at javax.swing.JComponent.processMouseEvent(JComponen t.java:3324)
at java.awt.Component.processEvent(Component.java:630 0)
at java.awt.Container.processEvent(Container.java:223 6)
at java.awt.Component.dispatchEventImpl(Component.jav a:4891)
at java.awt.Container.dispatchEventImpl(Container.jav a:2294)
at java.awt.Component.dispatchEvent(Component.java:47 13)
at java.awt.LightweightDispatcher.retargetMouseEvent( Container.java:4888)
at java.awt.LightweightDispatcher.processMouseEvent(C ontainer.java:4525)
at java.awt.LightweightDispatcher.dispatchEvent(Conta iner.java:4466)
at java.awt.Container.dispatchEventImpl(Container.jav a:2280)
at java.awt.Window.dispatchEventImpl(Window.java:2750 )
at java.awt.Component.dispatchEvent(Component.java:47 13)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.j ava:758)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessI mpl.doIntersectionPrivilege(ProtectionDomain.java: 76)
at java.security.ProtectionDomain$JavaSecurityAccessI mpl.doIntersectionPrivilege(ProtectionDomain.java: 86)
at java.awt.EventQueue$4.run(EventQueue.java:731)
at java.awt.EventQueue$4.run(EventQueue.java:729)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessI mpl.doIntersectionPrivilege(ProtectionDomain.java: 76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java: 728)
at java.awt.EventDispatchThread.pumpOneEventForFilter s(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(E ventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThre ad.java:82)

Código:

package academia;
import java.awt.Color;
import java.awt.*;
/**
 *
 * @author UNI
 */
public class TAcolor extends javax.swing.JFrame {

    /**
     * Creates new form TAcolor
     */
   
        public TAcolor(RegistroAlumnos reg){
        this();
        
      
        this.reg=reg;
    }         

    
 private TAcolor() {
        initComponents();
    }


 

    private void JBnegroActionPerformed(java.awt.event.ActionEvent evt) {                                        
        // TODO add your handling code here:
              

        if (JBnegro==evt.getSource()){
       
        
        
        }
    }                                       

    private void JBgrisActionPerformed(java.awt.event.ActionEvent evt) {                                       
        // TODO add your handling code here:
       
        reg.setColorFondo(java.awt.Color.GRAY);
        
    }                                      
 
    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
      

        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new TAcolor().setVisible(true);
            }
        });
    }

   
    
     private RegistroAlumnos reg;
    // Variables declaration - do not modify                     
    private javax.swing.JButton JBazul;
    private javax.swing.JButton JBgris;
    private javax.swing.JButton JBnegro;
    // End of variables declaration                   
}

El error creo que es básicamente en como hago referencia a la ventana donde se encuentra el JTextArea desde la que tiene los 3 botones que no se exactamente como hacerlo o si lo estoy haciendo bien si quiera.