...
 public   class  MyPanel  extends  JPanel  
{
     private  String text = "I can write";
     private   int  X_text =  10 ;
     private   int  Y_text =  20 ;

     public   void  PaintText(Graphics aGraphics)
    {
         super .paintComponent(aGraphics);
        aGraphics.drawString(text, X_text, Y_text);
    }
}
///////////////////
 class  SimpleFrame  extends  JFrame 
{
     public   int  DEFAULT_WIDTH =  300 ;
     public   int  DEFAULT_HEIGHT =  200 ;

     public  SimpleFrame()
    {
        setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
    }
...
     public   void  ShowText()
    {
        MyPanel newpanel =  new  MyPanel();
        Container contentPanel = getContentPane();
        contentPanel.add(newpanel);
    }
}
//////////////////
 public   class  GUITest {

     public   static   void  main(String[] args) {
       
        SimpleFrame newframe =  new  SimpleFrame();
        newframe.ShowText();
        newframe.show();
    }
}