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Java AWT Scrollbar Examples

Usage:

The Scrollbar lets the user graphically select a value by sliding a knob within a bounded interval.

Package:

Java.awt

Subclass of:

Java.awt.Component

Common Constructors:

Scrollbar (): Creates a Scrollbar instance with a range of 0-100, an initial value of 0, and vertical orientation.
Scrollbar (int Orientation): Creates a Scrollbar instance with a range of 0-100, an initial value of 0, and the specified orientation.

Common Methods:

addAdjustmentListener (AdjustmentListener Handler): Configures an event handler for the scrollbar.
getValue (): Returns the value of the scrollbar setting.
setBackground (Color BackgroundColor): Sets the background color of the scrollbar.
setMaximum (int Max): Sets the maximum value of the scrollbar.
setMinimum (int Min): Sets the minimum value of the scrollbar.
setValue (int Value): Sets the current value of the scrollbar.

Arguments:

BackgroundColor

The color to be used for the background of the field.

Handler

The object which handles action events from this field.

Max

The maximum value of the scrollbar.

Min

The minimum value of the scrollbar.

Orientation

The orientation of the scrollbar.

Scrollbar.HORIZONTAL: Orients the scrollbar horizontally.

Scrollbar.VERTICAL: Orients the scrollbar vertically.

Value

The current value of the scrollbar.

Example:

Code:

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

public class Scrollbar2 extends Applet implements AdjustmentListener {
  /* Declaration */
  private LayoutManager Layout;
  private Scrollbar HSelector;
  private Scrollbar VSelector;
  private Drawing Pad;
  private Label Report;

  public Scrollbar2 () {
    /* Instantiation */
    Layout = new BorderLayout ();
    HSelector = new Scrollbar ();
    VSelector = new Scrollbar (Scrollbar.VERTICAL);
    Pad = new Drawing ();
    Report = new Label ();

    /* Decoration */
    HSelector.setMaximum (300);
    HSelector.setOrientation (Scrollbar.HORIZONTAL);
    VSelector.setMaximum (300);
    Report.setAlignment (Label.CENTER);
    Pad.setBackground (Color.yellow);
    
    /* Location */
    setLayout (Layout);
    add ("South", Report);   
    add ("North", HSelector);
    add ("West", VSelector);
    add ("Center", Pad);
                    
    /* Configuration */
    HSelector.addAdjustmentListener (this);
    VSelector.addAdjustmentListener (this);
    
    /* Initialization */
    HSelector.setValue (100);
    VSelector.setValue (150);
    Pad.setOval (100, 150);
    Report.setText ("H = " + HSelector.getValue() +
                    ", V = " + VSelector.getValue());
  }

  public void adjustmentValueChanged(AdjustmentEvent e) {
    Report.setText ("H = " + HSelector.getValue() +
                    ", V = " + VSelector.getValue());
    Pad.setOval (HSelector.getValue (), VSelector.getValue ());
    Pad.repaint();
  } 

}

class Drawing extends Canvas {
  /* Declaration */
  private int X; 
  private int Y;
          
  public void setOval (int H, int V) {
    X = H;
    Y = V;              
  }             
          
  public void paint (Graphics g) {
    g.drawOval (10, 10, X, Y);
  }

}

	Java AWT Controls Sampler
	Java Swing JScrollbar Examples
	Java Swing JSlider Examples
	Class Scrollbar API	Sun Java site

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