JFrame frame = new JFrame("Shared Model");
JTextArea areaFiftyOne = new JTextArea( );
JTextArea areaFiftyTwo = new JTextArea( );
areaFiftyTwo.setDocument(areaFiftyOne.getDocument( ));
JTextArea areaFiftyThree = new JTextArea( );
areaFiftyThree.setDocument(areaFiftyOne.getDocument( ));
Container content = frame.getContentPane();
content.setLayout(new GridLayout(3, 1));
content.add(new JScrollPane(areaFiftyOne));
content.add(new JScrollPane(areaFiftyTwo));
content.add(new JScrollPane(areaFiftyThree));
frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
frame.setSize(300, 300);
frame.setVisible(true);