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Show the Value of Scroll Bar in Java Swing

                         

In this section, you will learn how to show the value of scrolling position in the text box. The scroll bar has multiples components as like: scrollbar top arrow, scrollbar slider, scrollbar track and scrollbar bottom arrow. When you scroll the scrollbar with the help of these components then you get the value of scrolling positions.

This program shows a scrollbar and text field on the panel like the following figure:

Values of the scroll bar in the text box

The panel is situated on the frame or window. The text area can have two types of scrollbar like: horizontal and vertical. The text field holds the value of scrolling position of scrollbar when you scroll the scrollbar. Following methods and APIs have been used for getting the value of scrollbar position.

getHorizontalScrollBar(): 
This method is used for handling the horizontal scrollbar tool. The getHorizontalScrollBar method returns the horizontal scrollbar object in the JScrollPane component of Java Swing. Hence, the JScrollPane is used for another object of the Java Swing for which the value of JScrollBar is increased and decreased.

getVerticalScrollBar():
This is method of JScrollPane class which is used to handle the vertical scrollbar of Java Swing. This method returns the vertical scrollbar object in the JScrollPane component of Java Swing.

AdjustmentListener:
This is the interface extends EventListener. This interface is used to receive generated adjustment events for the scrollbar.

adjustmentValueChanged(AdjustmentEvent ae):
This is the method which receives the adjustment event when you change the value of the scrollbar by scrolling that.

Here is the code of program:

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class ChangeScrollBarValue{
  JFrame frame;
  JPanel panel;
  JTextArea area;
  JTextField field;
  JScrollPane spane;
  public static void main(String[] args) {
    ChangeScrollBarValue v = new ChangeScrollBarValue();
  }

  public ChangeScrollBarValue(){
    String str = "Wellcome to RoseIndia.net. \n " "This is a web 
site \ndevelopement company. \n " 
"This is responsible for \nyour 
given tasks .\n " 
"It always full- fill to \nyour requirements \n ";
    frame = new JFrame("Show the Value of Scroll Bar in Java Swing");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    panel = new JPanel();
    area = new JTextArea(str, 57);
    spane = new JScrollPane(area);
    spane.getHorizontalScrollBar().addAdjustmentListener(new MyAction());
    spane.getVerticalScrollBar().addAdjustmentListener(new MyAction());
    field = new JTextField(10);
    panel.add(field);
    panel.add(spane);
    frame.add(panel);
    frame.setSize(400400);
    frame.setVisible(true);
  }

  public class MyAction implements AdjustmentListener{
    public void adjustmentValueChanged(AdjustmentEvent ae){
      int value = ae.getValue();
      String st = Integer.toString(value);
      field.setText(st);
    }
  }
}

Download this example.

                         

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