/*
Error:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
        at LansinTVserver.CheckStatus.CheckDetails(CheckStatus.java:26)
        at LansinTVserver.MainFrame$2.run(MainFrame.java:152)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:461)
        at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:242)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:163)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:157)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:149)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)

*/


public class MainFrame extends javax.swing.JFrame {
...

    public void Set_jTextArea_Status (String TextToAppend) {
            jTextArea_Status.append(TextToAppend);
    }


    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                
                MainFrame a = new MainFrame();
                CheckStatus b = new CheckStatus(a); 
                
                b.CheckDetails();
                
                
                a.setVisible(true);

            }
        });
    }

...}






public class CheckStatus {
    MainFrame a;
    
    public CheckStatus(MainFrame a) {
        
    }
    
    
    
    public void CheckDetails()  
    {  
        a.Set_jTextArea_Status("CheckVersionjhgh");
    } 
    
    
    
    public String CheckVersion() {
        return "LansinTVserver v4.01";
    }
           
}