Java by API/javax.swing/JScrollBar — различия между версиями

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Текущая версия на 14:18, 31 мая 2010

JScrollBar: addAdjustmentListener(AdjustmentListener l)

 
import java.awt.BorderLayout;
import java.awt.event.AdjustmentEvent;
import java.awt.event.AdjustmentListener;
import javax.swing.JFrame;
import javax.swing.JScrollBar;
public class MainClass {
  public static void main(String args[]) throws Exception {
    AdjustmentListener adjustmentListener = new AdjustmentListener() {
      public void adjustmentValueChanged(AdjustmentEvent adjustmentEvent) {
        System.out.println("Adjusted: " + adjustmentEvent.getValue());
      }
    };
    JScrollBar oneJScrollBar = new JScrollBar(JScrollBar.HORIZONTAL);
    oneJScrollBar.addAdjustmentListener(adjustmentListener);

    JFrame frame = new JFrame("ScrollBars R Us");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.add(oneJScrollBar, BorderLayout.NORTH);
    frame.setSize(300, 200);
    frame.setVisible(true);
  }
}





JScrollBar: getBlockIncrement(int direction)

 
/*
 *
 * Copyright (c) 1998 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Sun grants you ("Licensee") a non-exclusive, royalty free, license to use,
 * modify and redistribute this software in source and binary code form,
 * provided that i) this copyright notice and license appear on all copies of
 * the software; and ii) Licensee does not utilize the software in a manner
 * which is disparaging to Sun.
 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING ANY
 * IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR
 * NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE
 * LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING
 * OR DISTRIBUTING THE SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS
 * LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT,
 * INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER
 * CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF
 * OR INABILITY TO USE SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGES.
 *
 * This software is not designed or intended for use in on-line control of
 * aircraft, air traffic, aircraft navigation or aircraft communications; or in
 * the design, construction, operation or maintenance of any nuclear
 * facility. Licensee represents and warrants that it will not use or
 * redistribute the Software for such purposes.
 */
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.MouseWheelEvent;
import java.awt.event.MouseWheelListener;
import javax.swing.BorderFactory;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
public class Main extends JPanel implements MouseWheelListener {
  JTextArea textArea = new JTextArea();
  JScrollPane scrollPane = new JScrollPane(textArea);
  final static String newline = "\n";
  public Main() {
    super(new BorderLayout());
    textArea.setEditable(false);
    
    scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
    scrollPane.setPreferredSize(new Dimension(400, 250));
    add(scrollPane, BorderLayout.CENTER);
    textArea.append("This text area displays information " + "about its mouse wheel events."
        + newline);
    textArea.addMouseWheelListener(this);
    setPreferredSize(new Dimension(450, 350));
    setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));
  }
  public void mouseWheelMoved(MouseWheelEvent e) {
    String message;
    int notches = e.getWheelRotation();
    if (notches < 0) {
      message = "Mouse wheel moved UP " + -notches + " notch(es)" + newline;
    } else {
      message = "Mouse wheel moved DOWN " + notches + " notch(es)" + newline;
    }
    if (e.getScrollType() == MouseWheelEvent.WHEEL_UNIT_SCROLL) {
      message += "    Scroll type: WHEEL_UNIT_SCROLL" + newline;
      message += "    Scroll amount: " + e.getScrollAmount() + " unit increments per notch"
          + newline;
      message += "    Units to scroll: " + e.getUnitsToScroll() + " unit increments" + newline;
      message += "    Vertical unit increment: "
          + scrollPane.getVerticalScrollBar().getUnitIncrement(1) + " pixels" + newline;
    } else { // scroll type == MouseWheelEvent.WHEEL_BLOCK_SCROLL
      message += "    Scroll type: WHEEL_BLOCK_SCROLL" + newline;
      message += "    Vertical block increment: "
          + scrollPane.getVerticalScrollBar().getBlockIncrement(1) + " pixels" + newline;
    }
    saySomething(message, e);
  }
  void saySomething(String eventDescription, MouseWheelEvent e) {
    textArea.append(e.getComponent().getClass().getName() + ": " + eventDescription);
    textArea.setCaretPosition(textArea.getDocument().getLength());
  }
  public static void main(String[] args) {
    JFrame frame = new JFrame("MouseWheelEventDemo");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JComponent newContentPane = new Main();
    newContentPane.setOpaque(true);
    frame.setContentPane(newContentPane);
    frame.pack();
    frame.setVisible(true);
  }
}





JScrollBar: getMinimum()

 
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JScrollBar;
import javax.swing.JScrollPane;
import javax.swing.border.LineBorder;
public class MainClass {
  public static void main(String args[]) throws Exception {
    JFrame frame = new JFrame("Cornering Sample");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JButton button = new JButton("+");
    
    JLabel bigLabel = new JLabel("A");
    bigLabel.setPreferredSize(new Dimension(400,400));
    bigLabel.setBorder(new LineBorder(Color.red));
    
    JScrollPane scrollPane = new JScrollPane(bigLabel);
    scrollPane.setCorner(JScrollPane.UPPER_LEFT_CORNER, button);
    scrollPane.setColumnHeaderView(new JLabel("B"));
    scrollPane.setRowHeaderView(new JLabel("C"));
    ActionListener actionListener = new JScrollPaneToTopAction(scrollPane);
    button.addActionListener(actionListener);
    frame.add(scrollPane, BorderLayout.CENTER);
    frame.setSize(300, 200);
    frame.setVisible(true);
  }
}

class JScrollPaneToTopAction implements ActionListener {
  JScrollPane scrollPane;
  public JScrollPaneToTopAction(JScrollPane scrollPane) {
    if (scrollPane == null) {
      throw new IllegalArgumentException("JScrollPaneToTopAction: null JScrollPane");
    }
    this.scrollPane = scrollPane;
  }
  public void actionPerformed(ActionEvent actionEvent) {
    JScrollBar verticalScrollBar   = scrollPane.getVerticalScrollBar();
    JScrollBar horizontalScrollBar = scrollPane.getHorizontalScrollBar();
    verticalScrollBar.setValue(verticalScrollBar.getMinimum());
    horizontalScrollBar.setValue(horizontalScrollBar.getMinimum());
  }
}





JScrollBar: getModel()

 
import java.awt.BorderLayout;
import javax.swing.BoundedRangeModel;
import javax.swing.JFrame;
import javax.swing.JProgressBar;
import javax.swing.JScrollBar;
import javax.swing.JSlider;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
public class MainClass {
  public static void main(String args[]) throws Exception {
    ChangeListener changeListener = new BoundedChangeListener();
    JScrollBar anotherJScrollBar = new JScrollBar(JScrollBar.HORIZONTAL);
    BoundedRangeModel model = anotherJScrollBar.getModel();
    model.addChangeListener(changeListener);
    JFrame frame = new JFrame("ScrollBars R Us");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.add(anotherJScrollBar, BorderLayout.NORTH);
    frame.setSize(300, 200);
    frame.setVisible(true);
  }
}
class BoundedChangeListener implements ChangeListener {
  public void stateChanged(ChangeEvent changeEvent) {
    Object source = changeEvent.getSource();
    if (source instanceof BoundedRangeModel) {
      BoundedRangeModel aModel = (BoundedRangeModel) source;
      if (!aModel.getValueIsAdjusting()) {
        System.out.println("Changed: " + aModel.getValue());
      }
    } else if (source instanceof JSlider) {
      JSlider theJSlider = (JSlider) source;
      if (!theJSlider.getValueIsAdjusting()) {
        System.out.println("Slider changed: " + theJSlider.getValue());
      }
    } else if (source instanceof JProgressBar) {
      JProgressBar theJProgressBar = (JProgressBar) source;
      System.out.println("ProgressBar changed: " + theJProgressBar.getValue());
    } else {
      System.out.println("Something changed: " + source);
    }
  }
}





JScrollBar: getUnitIncrement(int direction)

 
/*
 *
 * Copyright (c) 1998 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Sun grants you ("Licensee") a non-exclusive, royalty free, license to use,
 * modify and redistribute this software in source and binary code form,
 * provided that i) this copyright notice and license appear on all copies of
 * the software; and ii) Licensee does not utilize the software in a manner
 * which is disparaging to Sun.
 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING ANY
 * IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR
 * NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE
 * LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING
 * OR DISTRIBUTING THE SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS
 * LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT,
 * INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER
 * CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF
 * OR INABILITY TO USE SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGES.
 *
 * This software is not designed or intended for use in on-line control of
 * aircraft, air traffic, aircraft navigation or aircraft communications; or in
 * the design, construction, operation or maintenance of any nuclear
 * facility. Licensee represents and warrants that it will not use or
 * redistribute the Software for such purposes.
 */
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.MouseWheelEvent;
import java.awt.event.MouseWheelListener;
import javax.swing.BorderFactory;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
public class Main extends JPanel implements MouseWheelListener {
  JTextArea textArea = new JTextArea();
  JScrollPane scrollPane = new JScrollPane(textArea);
  final static String newline = "\n";
  public Main() {
    super(new BorderLayout());
    textArea.setEditable(false);
    
    scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
    scrollPane.setPreferredSize(new Dimension(400, 250));
    add(scrollPane, BorderLayout.CENTER);
    textArea.append("This text area displays information " + "about its mouse wheel events."
        + newline);
    textArea.addMouseWheelListener(this);
    setPreferredSize(new Dimension(450, 350));
    setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));
  }
  public void mouseWheelMoved(MouseWheelEvent e) {
    String message;
    int notches = e.getWheelRotation();
    if (notches < 0) {
      message = "Mouse wheel moved UP " + -notches + " notch(es)" + newline;
    } else {
      message = "Mouse wheel moved DOWN " + notches + " notch(es)" + newline;
    }
    if (e.getScrollType() == MouseWheelEvent.WHEEL_UNIT_SCROLL) {
      message += "    Scroll type: WHEEL_UNIT_SCROLL" + newline;
      message += "    Scroll amount: " + e.getScrollAmount() + " unit increments per notch"
          + newline;
      message += "    Units to scroll: " + e.getUnitsToScroll() + " unit increments" + newline;
      message += "    Vertical unit increment: "
          + scrollPane.getVerticalScrollBar().getUnitIncrement(1) + " pixels" + newline;
    } else { // scroll type == MouseWheelEvent.WHEEL_BLOCK_SCROLL
      message += "    Scroll type: WHEEL_BLOCK_SCROLL" + newline;
      message += "    Vertical block increment: "
          + scrollPane.getVerticalScrollBar().getBlockIncrement(1) + " pixels" + newline;
    }
    saySomething(message, e);
  }
  void saySomething(String eventDescription, MouseWheelEvent e) {
    textArea.append(e.getComponent().getClass().getName() + ": " + eventDescription);
    textArea.setCaretPosition(textArea.getDocument().getLength());
  }
  public static void main(String[] args) {
    JFrame frame = new JFrame("MouseWheelEventDemo");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JComponent newContentPane = new Main();
    newContentPane.setOpaque(true);
    frame.setContentPane(newContentPane);
    frame.pack();
    frame.setVisible(true);
  }
}





JScrollBar.HORIZONTAL

 
import java.awt.BorderLayout;
import javax.swing.JFrame;
import javax.swing.JScrollBar;
public class MainClass {
  public static void main(String args[]) throws Exception {
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JScrollBar oneJScrollBar = new JScrollBar(JScrollBar.HORIZONTAL);
    frame.add(oneJScrollBar, BorderLayout.NORTH);
    frame.setSize(200, 44);
    frame.setVisible(true);
  }
}





JScrollBar: setBlockIncrement(int blockIncrement)

 
import java.awt.BorderLayout;
import java.awt.event.AdjustmentEvent;
import java.awt.event.AdjustmentListener;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollBar;
public class MainClass extends JPanel {
  JLabel label = new JLabel();
  public MainClass() {
    super(true);
    
    setLayout(new BorderLayout());
    JScrollBar hbar = new JScrollBar(JScrollBar.HORIZONTAL, 30, 20, 0, 300);
    JScrollBar vbar = new JScrollBar(JScrollBar.VERTICAL, 30, 40, 0, 300);
    hbar.setUnitIncrement(2);
    hbar.setBlockIncrement(1);
    hbar.addAdjustmentListener(new MyAdjustmentListener());
    vbar.addAdjustmentListener(new MyAdjustmentListener());
    add(hbar, BorderLayout.SOUTH);
    add(vbar, BorderLayout.EAST);
    add(label, BorderLayout.CENTER);
  }
  class MyAdjustmentListener implements AdjustmentListener {
    public void adjustmentValueChanged(AdjustmentEvent e) {
      label.setText("    New Value is " + e.getValue() + "      ");
      repaint();
    }
  }
  public static void main(String s[]) {
    JFrame frame = new JFrame("Scroll Bar Example");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setContentPane(new MainClass());
    frame.setSize(200, 200);
    frame.setVisible(true);
  }
}





JScrollBar: setFocusable(boolean focusable)

 
import java.awt.Dimension;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import java.util.Vector;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextField;
public class Main extends JPanel implements FocusListener {
  public Main() {
    JTextField textField = new JTextField("A TextField");
    textField.addFocusListener(this);
    JLabel label = new JLabel("A Label");
    label.addFocusListener(this);
    add(label);
    String comboPrefix = "ComboBox Item #";
    final int numItems = 15;
    Vector vector = new Vector(numItems);
    for (int i = 0; i < numItems; i++) {
      vector.addElement(comboPrefix + i);
    }
    JComboBox comboBox = new JComboBox(vector);
    comboBox.addFocusListener(this);
    add(comboBox);
    JButton button = new JButton("A Button");
    button.addFocusListener(this);
    add(button);
    String listPrefix = "List Item #";
    Vector listVector = new Vector(numItems);
    for (int i = 0; i < numItems; i++) {
      listVector.addElement(listPrefix + i);
    }
    JList list = new JList(listVector);
    list.setSelectedIndex(1);
    list.addFocusListener(this);
    JScrollPane listScrollPane = new JScrollPane(list);
    listScrollPane.getVerticalScrollBar().setFocusable(false);
    listScrollPane.getHorizontalScrollBar().setFocusable(false);
    add(listScrollPane);
    setPreferredSize(new Dimension(450, 450));
    setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));
  }
  void displayMessage(String prefix, FocusEvent e) {
    System.out.println(prefix
        + (e.isTemporary() ? " (temporary):" : ":")
        + e.getComponent().getClass().getName()
        + "; Opposite component: "
        + (e.getOppositeComponent() != null ? e.getOppositeComponent().getClass().getName()
            : "null"));
  }
  public static void main(String[] args) {
    JFrame frame = new JFrame("FocusEventDemo");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JComponent newContentPane = new Main();
    newContentPane.setOpaque(true); // content panes must be opaque
    frame.setContentPane(newContentPane);
    frame.pack();
    frame.setVisible(true);
  }
  public void focusGained(FocusEvent e) {
    displayMessage("Focus gained", e);
  }
  public void focusLost(FocusEvent e) {
    displayMessage("Focus lost", e);
  }
}





JScrollBar: setUnitIncrement(int unitIncrement)

 
import java.awt.BorderLayout;
import java.awt.event.AdjustmentEvent;
import java.awt.event.AdjustmentListener;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollBar;
public class MainClass extends JPanel {
  JLabel label = new JLabel();
  public MainClass() {
    super(true);
    
    setLayout(new BorderLayout());
    JScrollBar hbar = new JScrollBar(JScrollBar.HORIZONTAL, 30, 20, 0, 300);
    JScrollBar vbar = new JScrollBar(JScrollBar.VERTICAL, 30, 40, 0, 300);
    hbar.setUnitIncrement(2);
    hbar.setBlockIncrement(1);
    hbar.addAdjustmentListener(new MyAdjustmentListener());
    vbar.addAdjustmentListener(new MyAdjustmentListener());
    add(hbar, BorderLayout.SOUTH);
    add(vbar, BorderLayout.EAST);
    add(label, BorderLayout.CENTER);
  }
  class MyAdjustmentListener implements AdjustmentListener {
    public void adjustmentValueChanged(AdjustmentEvent e) {
      label.setText("    New Value is " + e.getValue() + "      ");
      repaint();
    }
  }
  public static void main(String s[]) {
    JFrame frame = new JFrame("Scroll Bar Example");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setContentPane(new MainClass());
    frame.setSize(200, 200);
    frame.setVisible(true);
  }
}





JScrollBar: setValue(int value)

 
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JScrollBar;
import javax.swing.JScrollPane;
import javax.swing.border.LineBorder;
public class MainClass {
  public static void main(String args[]) throws Exception {
    JFrame frame = new JFrame("Cornering Sample");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JButton button = new JButton("+");
    
    JLabel bigLabel = new JLabel("A");
    bigLabel.setPreferredSize(new Dimension(400,400));
    bigLabel.setBorder(new LineBorder(Color.red));
    
    JScrollPane scrollPane = new JScrollPane(bigLabel);
    scrollPane.setCorner(JScrollPane.UPPER_LEFT_CORNER, button);
    scrollPane.setColumnHeaderView(new JLabel("B"));
    scrollPane.setRowHeaderView(new JLabel("C"));
    ActionListener actionListener = new JScrollPaneToTopAction(scrollPane);
    button.addActionListener(actionListener);
    frame.add(scrollPane, BorderLayout.CENTER);
    frame.setSize(300, 200);
    frame.setVisible(true);
  }
}

class JScrollPaneToTopAction implements ActionListener {
  JScrollPane scrollPane;
  public JScrollPaneToTopAction(JScrollPane scrollPane) {
    if (scrollPane == null) {
      throw new IllegalArgumentException("JScrollPaneToTopAction: null JScrollPane");
    }
    this.scrollPane = scrollPane;
  }
  public void actionPerformed(ActionEvent actionEvent) {
    JScrollBar verticalScrollBar   = scrollPane.getVerticalScrollBar();
    JScrollBar horizontalScrollBar = scrollPane.getHorizontalScrollBar();
    verticalScrollBar.setValue(verticalScrollBar.getMinimum());
    horizontalScrollBar.setValue(horizontalScrollBar.getMinimum());
  }
}





new JScrollBar(int orientation)

 
import java.awt.BorderLayout;
import javax.swing.JFrame;
import javax.swing.JScrollBar;
public class MainClass {
  public static void main(String args[]) throws Exception {
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JScrollBar oneJScrollBar = new JScrollBar(JScrollBar.HORIZONTAL);
    frame.add(oneJScrollBar, BorderLayout.NORTH);
    frame.setSize(200, 44);
    frame.setVisible(true);
  }
}





new JScrollBar(int orientation, int value, int extent, int min, int max)

 
import java.awt.BorderLayout;
import java.awt.event.AdjustmentEvent;
import java.awt.event.AdjustmentListener;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollBar;
public class MainClass extends JPanel {
  JLabel label = new JLabel();
  public MainClass() {
    super(true);
    
    setLayout(new BorderLayout());
    JScrollBar hbar = new JScrollBar(JScrollBar.HORIZONTAL, 30, 20, 0, 300);
    JScrollBar vbar = new JScrollBar(JScrollBar.VERTICAL, 30, 40, 0, 300);
    hbar.setUnitIncrement(2);
    hbar.setBlockIncrement(1);
    hbar.addAdjustmentListener(new MyAdjustmentListener());
    vbar.addAdjustmentListener(new MyAdjustmentListener());
    add(hbar, BorderLayout.SOUTH);
    add(vbar, BorderLayout.EAST);
    add(label, BorderLayout.CENTER);
  }
  class MyAdjustmentListener implements AdjustmentListener {
    public void adjustmentValueChanged(AdjustmentEvent e) {
      label.setText("    New Value is " + e.getValue() + "      ");
      repaint();
    }
  }
  public static void main(String s[]) {
    JFrame frame = new JFrame("Scroll Bar Example");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setContentPane(new MainClass());
    frame.setSize(200, 200);
    frame.setVisible(true);
  }
}