import java.awt.BorderLayout;

import java.awt.Color;

import java.awt.Component;

import java.awt.Dimension;

import java.awt.GridLayout;

import java.awt.event.AdjustmentEvent;

import java.awt.event.AdjustmentListener;

import java.awt.event.ComponentAdapter;

import java.awt.event.ComponentEvent;

import java.util.Vector;

import javax.swing.JComponent;

import javax.swing.JFrame;

import javax.swing.JPanel;

import javax.swing.JScrollBar;

import javax.swing.JScrollPane;

import javax.swing.JTextArea;

import javax.swing.SwingUtilities;

import javax.swing.ScrollPaneConstants;

public class SyncTest extends JFrame {

//임시로 텍스트 화면으로 대체함....

public JTextArea textArea1 = new JTextArea();

    public JTextArea textArea2 = new JTextArea();

    public SyncTest() {

    this.setSize(800, 600);

    //왼쪽 pane

        JScrollPane jsp1 = new JScrollPane(new SyncSizePanel(textArea1));

        jsp1.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_NEVER);

        //오른쪽 pane

        JScrollPane jsp2 = new JScrollPane(new SyncSizePanel(textArea2));

        final JScrollBar vScroll1 = jsp1.getVerticalScrollBar();

        final JScrollBar vScroll2 = jsp2.getVerticalScrollBar();

        vScroll1.addAdjustmentListener(new AdjustmentListener() { //무명클래스...

            public void adjustmentValueChanged(AdjustmentEvent e) {

            //vScroll1->vScroll2 서로를 바라봐야함

                vScroll2.setValue(e.getValue());

            }

        });

        vScroll2.addAdjustmentListener(new AdjustmentListener() {

            public void adjustmentValueChanged(AdjustmentEvent e) {

                vScroll1.setValue(e.getValue());

            }

        });

        this.getContentPane().setLayout(new GridLayout(1, 2));

        this.getContentPane().add(jsp1);

        this.getContentPane().add(jsp2);

        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    }

    public static void main(String[] args) {

        SyncTest syncTest = new SyncTest();

        syncTest.setVisible(true);

        //출력 Test text 나열....

        StringBuffer buffer = new StringBuffer();

        for (int i = 0; i < 300; i++) {

            buffer.append("testpage1-" + i + "\n");

        }

        syncTest.textArea1.setText(buffer.toString());

        buffer.delete(0, buffer.length());

        for (int i = 0; i < 300; i++) {

            buffer.append("testpage2-" + i + "\n");

        }

        syncTest.textArea2.setText(buffer.toString());

    }

}

/* SyncSizePanel클래스 */

class SyncSizePanel extends JPanel {

   private static Vector panels = new Vector();

    private JPanel spacer = new JPanel();

    public JComponent component;

    public SyncSizePanel(JComponent component) {

        spacer.setBackground(Color.WHITE);

        this.component = component;

        this.setLayout(new BorderLayout());

        this.add(component, BorderLayout.CENTER);

        this.add(spacer, BorderLayout.SOUTH);

        component.addComponentListener(new ComponentAdapter() {

            public void componentResized(ComponentEvent e) {

                syncComponentSizes();

            }

        });

    }

    private void syncComponentSizes() {

        Dimension d = component.getPreferredSize();

        int w = d.width;

        int h = d.height;

        for (int i = 0; i < panels.size(); i++) {

            SyncSizePanel panel = (SyncSizePanel) panels.get(i);

            Component c = panel.component;

            if (panel != this) {

                Dimension d2 = c.getPreferredSize();

                w = w > d2.width ? w : d2.width;

                h = h > d2.height ? h : d2.height;

            }

        }

        for (int i = 0; i < panels.size(); i++) {

            SyncSizePanel panel = (SyncSizePanel) panels.get(i);

            panel.setSyncSize(w, h);

        }

    }

    private void setSyncSize(int width, int height) {

        Dimension d = component.getPreferredSize();

        spacer.setPreferredSize(new Dimension(width - d.width, height - d.height));

        revalidate();

    }

}