how my scrollbar works?

[vishnu vardhan brundavanam]

hi....
i wrote code to draw a graph(line) by tacking data from a file ....the code for that is here...

  


	import java.awt.*; 
	import java.awt.font.*;
	import java.awt.geom.*;
	import java.io.BufferedReader;
	import java.io.FileReader;

        import javax.swing.*;

	public class ShowGraph1 extends JPanel {

		int data[];

		public ShowGraph1(String srcfile) throws Exception {
			
			BufferedReader src1 = new BufferedReader(new FileReader(srcfile));
			String str;
			int i1 = 0, counter = 0;

			while ((str = src1.readLine()) != null) {
				counter++;
			}// src1.close();
			data = new int[counter];

			//

			// src1.close();
		//	 System.out.println(counter);
			BufferedReader src11 = new BufferedReader(new FileReader(srcfile));
			try {

				while ((str = src11.readLine()) != null) {
					// System.out.println(str);

					int a = (int) Integer.parseInt(str.trim());
					data[i1] = a;
					i1++;

				}

			} catch (NumberFormatException n) {
				n.printStackTrace();
			}
			src11.close();

		}
	
		final int PAD = 20;
	
		public void paintComponent(Graphics g) {
			
			super.paintComponent(g);
			
			Graphics2D g2 = (Graphics2D) g;
			g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
					RenderingHints.VALUE_ANTIALIAS_ON);
			
			int w =5* getWidth();
			int h = getHeight();
			
			
			g2.draw(new Line2D.Double(PAD, PAD, PAD, h - PAD));
			
			g2.draw(new Line2D.Double(PAD, h - PAD, w - PAD, h - PAD));
			
			
			Font font = g2.getFont();
			FontRenderContext frc = g2.getFontRenderContext();
			LineMetrics lm = font.getLineMetrics("0", frc);
			float sh = lm.getAscent() + lm.getDescent();
			
			
			String s = " data ";
			float sy = PAD + ((h - 2 * PAD) - s.length() * sh) / 2 + lm.getAscent();
			for (int i = 0; i < s.length(); i++) {
				String letter = String.valueOf(s.charAt(i));
					float sw = (float) font.getStringBounds(letter, frc).getWidth();
					float sx = (PAD - sw) / 2;
				
				g2.drawString(letter, sx, sy);
				sy += sh;
			}
			
			
			double xInc = 20;//(double) (w - 2 * PAD) / (data.length - 1);
			
			double scale = (double) (h - 2 * PAD) / getMax();
			double x1 = 0;
			g2.setPaint(Color.green.darker());
			for (int i = 0; i < data.length -1; i++) {
				 x1 = PAD + i *xInc;
				 double y1 = h - PAD - scale * data[i];
				 double x2 = PAD + (i + 1) * xInc;
				 double y2 = h - PAD - scale * data[i + 1];
				g2.draw(new Line2D.Double(x1, y1, x2, y2));
				
				g2.drawString((i+1)+"", (float) x1, h-(PAD-15));			
				
				}
			
			g2.setPaint(Color.red);
			for (int i = 0; i < data.length; i++) {
				double x = PAD + i * xInc;
				double y = h - PAD - scale * data[i];
				g2.fill(new Ellipse2D.Double(x - 2, y - 2, 4, 4));
			}
		}

		public int getMax() {
			int max = -Integer.MAX_VALUE;
			for (int i = 0; i < data.length; i++) {
				if (data[i] > max)
					max = data[i];
			}
			return max;
		
		}}

Now the problem is the scrollbar is not working to see complete graph when i'm giving many input values.......
The here is the calling class(main) of the above code.....

   
import java.awt.BorderLayout;
import javax.swing.JFrame;
import javax.swing.JScrollBar;
import javax.swing.JScrollPane;
public class DrawGraph1  {
	 

	public static void main(String[] args) throws Exception {

		//JPanel p = new JPanel();
		JFrame frame = new JFrame();
		JScrollBar jscbHort = new JScrollBar();
		 frame.getContentPane().add(jscbHort, BorderLayout.SOUTH);
		 jscbHort.addAdjustmentListener(new M());
		ShowGraph1 g = new ShowGraph1("C:\\data\\data.txt");
		
		
		// JScrollBar oneJScrollBar = new JScrollBar(JScrollBar.HORIZONTAL);
		// Container contentPane = frame.getContentPane();
		// contentPane.add(oneJScrollBar, BorderLayout.SOUTH);
		 JScrollBar hbar = new JScrollBar(JScrollBar.HORIZONTAL, 10, 50, 10,600);
		 JScrollPane jScrollPane = new JScrollPane(hbar);
		 /*
		 JScrollPane scrollpane = new JScrollPane(p);
		
		 c.add(scrollpane, BorderLayout.CENTER);
		// frame.getContentPane().add(hbar, BorderLayout.CENTER);
*/
		// Container contentPane = new Container();
		 frame.add(jScrollPane, BorderLayout.SOUTH);
		 hbar.setUnitIncrement(20);
		// hbar.setBlockIncrement(20);
		 hbar.addAdjustmentListener( new M());
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.add(g);
		frame.setSize(600, 600);
		// f.setLocation(200, 200);
		frame.setVisible(true);

		// hbar.setBlockIncrement(150);
		// hbar.setBlockIncrement(WIDTH);
		// frame.getContentPane().add(scrollpane, BorderLayout.CENTER);

		// hbar. setUnitIncrement (50);
		// hbar.getPageIncrement (15);
		// hbar.setLineIncrement (10);
		// JScrollPane scrollPane = null;
		// scrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
		// frame.add(jsp);

	}

	
}
 

the i don't how to implement this listener .....
----------------------------------------------------

  
import java.awt.Adjustable; 
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.AdjustmentEvent;
import java.awt.event.AdjustmentListener;

import javax.swing.JScrollBar;
import javax.swing.JScrollPane;

public class M implements AdjustmentListener {

	public void adjustmentValueChanged(AdjustmentEvent e) {
	
	}
	}
  

i'm attaching output screen also...actually there i haven taken around 90+ input values...

please help me .....
thank u....

[Maneesh Godbole]

Scrollbars work when the size of their child components exceed the available display say.
Try overriding getPreferredSize() in your panels (the one which paints the graphs)

[vishnu vardhan brundavanam]

could you show the code how to implement that getPreferredSize() in my application...?

[Darryl Burke]

@Override
public Dimension getPreferredSize() {
   int width, height;
   // compute and assign appropriate values for width and height
   return new Dimension(width, height);
}

[vishnu vardhan brundavanam]

could you please complete this program..?

[Darryl Burke]

Read the API for JScrollPane and follow the link to the Java tutorial on How to Use Scroll Panes, where you will find example code.