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AWT Scrollbar Class

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Scrollbar class

Introduction

Scrollbar class control represents a scroll bar component in order to enable users to select from a range of values.

Class declaration

The Following is the declaration for java.awt.Scrollbar class:

public class Scrollbar
   extends Component
      implements Adjustable, Accessible

Field

Following are the fields for java.awt.Image class:

  • static int HORIZONTAL –A constant that indicates a horizontal scroll bar.
  • static int VERTICAL –A constant that indicates a vertical scroll bar.

Class constructors

S.N.Constructor & Description
1Scrollbar()Constructs a new vertical scroll bar.
2Scrollbar(int orientation)Constructs a new scroll bar with the specified orientation.
3Scrollbar(int orientation, int value, int visible, int minimum, int maximum)Constructs a new scroll bar with the specified orientation, initial value, visible amount, and minimum and maximum values.

Class methods

S.N.Method & Description
1void addAdjustmentListener(AdjustmentListener l)Adds the specified adjustment listener to receive instances of AdjustmentEvent from this scroll bar.
2void addNotify()Creates the Scrollbar’s peer.
3int getBlockIncrement()Gets the block increment of this scroll bar.
4int getLineIncrement()Deprecated. As of JDK version 1.1, replaced by getUnitIncrement().
5int getMaximum()Gets the maximum value of this scroll bar.
6int getMinimum()Gets the minimum value of this scroll bar.
7int getOrientation()Returns the orientation of this scroll bar.
8int getPageIncrement()Deprecated. As of JDK version 1.1, replaced by getBlockIncrement().
9int getUnitIncrement()Gets the unit increment for this scrollbar.
10int getValue()Gets the current value of this scroll bar.
11booleangetValueIsAdjusting()Returns true if the value is in the process of changing as a result of actions being taken by the user.
12int getVisible()Deprecated. As of JDK version 1.1, replaced by getVisibleAmount().
13int getVisibleAmount()Gets the visible amount of this scroll bar.
14protected String paramString()Returns a string representing the state of this Scrollbar.
15protected void processAdjustmentEvent(AdjustmentEvent e)Processes adjustment events occurring on this scrollbar by dispatching them to any registered AdjustmentListener objects.
16protected void processEvent(AWTEvent e)Processes events on this scroll bar.
17void removeAdjustmentListener(AdjustmentListener l)Removes the specified adjustment listener so that it no longer receives instances of AdjustmentEvent from this scroll bar.
18void setBlockIncrement(int v)Sets the block increment for this scroll bar.
19void setLineIncrement(int v)Deprecated. As of JDK version 1.1, replaced by setUnitIncrement(int).
20void setMaximum(int newMaximum)Sets the maximum value of this scroll bar.
21void setMinimum(int newMinimum)Sets the minimum value of this scroll bar.
22void setOrientation(int orientation)Sets the orientation for this scroll bar.
23void setPageIncrement(int v)Deprecated. As of JDK version 1.1, replaced by setBlockIncrement().
24void setUnitIncrement(int v)Sets the unit increment for this scroll bar.
25void setValue(int newValue)Sets the value of this scroll bar to the specified value.
26void setValueIsAdjusting(boolean b)Sets the valueIsAdjusting property.
27void setValues(int value, int visible, int minimum, int maximum)Sets the values of four properties for this scroll bar: value, visibleAmount, minimum, and maximum.
28void setVisibleAmount(int newAmount)Sets the visible amount of this scroll bar.
29AccessibleContext getAccessibleContext()Gets the AccessibleContext associated with this Scrollbar.
30AdjustmentListener[] getAdjustmentListeners()Returns an array of all the adjustment listeners registered on this scrollbar.
31<T extends EventListener>T[] getListeners(Class<T> listenerType)Returns an array of all the objects currently registered as FooListeners upon this Scrollbar.

Methods inherited

This class inherits methods from the following classes:

  • java.awt.Component
  • java.lang.Object

Choice Example

Create the following java program using any editor of your choice in say D:/ > AWT > com > adglob > gui >AwtControlDemo

package com.adglob.gui;

import java.awt.*;
import java.awt.event.*;

public class AwtControlDemo {

   private Frame mainFrame;
   private Label headerLabel;
   private Label statusLabel;
   private Panel controlPanel;

   public AwtControlDemo(){
      prepareGUI();
   }

   public static void main(String[] args){
      AwtControlDemo  awtControlDemo = new AwtControlDemo();
      awtControlDemo.showScrollbarDemo();
   }

   private void prepareGUI(){
      mainFrame = new Frame("Java AWT Examples");
      mainFrame.setSize(400,400);
      mainFrame.setLayout(new GridLayout(3, 1));
      mainFrame.addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent windowEvent){
            System.exit(0);
         }        
      });    
      headerLabel = new Label();
      headerLabel.setAlignment(Label.CENTER);
      statusLabel = new Label();        
      statusLabel.setAlignment(Label.CENTER);
      statusLabel.setSize(350,100);

      controlPanel = new Panel();
      controlPanel.setLayout(new FlowLayout());

      mainFrame.add(headerLabel);
      mainFrame.add(controlPanel);
      mainFrame.add(statusLabel);
      mainFrame.setVisible(true);  
   }

   private void showScrollbarDemo(){                                       
      headerLabel.setText("Control in action: Scrollbar"); 

      final Scrollbar horizontalScroller = new Scrollbar(Scrollbar.HORIZONTAL);
      final Scrollbar verticalScroller = new Scrollbar();
      verticalScroller.setOrientation(Scrollbar.VERTICAL);
      horizontalScroller.setMaximum (100);
      horizontalScroller.setMinimum (1);
      verticalScroller.setMaximum (100);
      verticalScroller.setMinimum (1);

      horizontalScroller.addAdjustmentListener(new AdjustmentListener() {

         @Override
         public void adjustmentValueChanged(AdjustmentEvent e) {
            statusLabel.setText("Horozontal: "
               +horizontalScroller.getValue() 
               +" ,Vertical: "
               + verticalScroller.getValue());
            }
         });

      verticalScroller.addAdjustmentListener(new AdjustmentListener() {

            @Override
            public void adjustmentValueChanged(AdjustmentEvent e) {
               statusLabel.setText("Horozontal: "
               +horizontalScroller.getValue() 
               +" ,Vertical: "+ verticalScroller.getValue());
            }
         });

      controlPanel.add(horizontalScroller);
      controlPanel.add(verticalScroller);

      mainFrame.setVisible(true);  
   }
}

Compile the program using command prompt. Go to D:/ > AWT and type the following command.

D:\AWT>javac com\adglob\gui\AwtControlDemo.java

If no error comes that means compilation is successful. Run the program using following command.

D:\AWT>java com.adglob.gui.AwtControlDemo

Verify the following output

Scrollbar class

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