• Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 383
  • Last Modified:

FileReader info -> drawLine in graph

Anyone have an example of reading data from a data file
(FileReader, BufferedReader) then graphing the data
in an Applet (paint, drawLine)?

rjcole@clearsail.net
0
robjay
Asked:
robjay
  • 2
  • 2
1 Solution
 
heyhey_Commented:
here is some code - how to read some data from file and draw into the screen . Only Applications can access files on the local disk, if want to use this code in Applet you' have to change FileInputStream with new URL(...) and URL.getStream(); (so you'll get the information from the remote host)

data.txt
---start
10,10
100,10
100 100 10 100 10 10 50 50
---end

the app code
-- start

import java.util.*;
import java.io.*;
import java.awt.*;
import java.awt.event.*;


public class PaintTest extends Panel
{
    Vector data;

public PaintTest() {
    super();
 }

 public void paint(Graphics g)
 {
    if (data == null) return;
    int len = data.size();
    if (len < 2) return;
    int[] cur;
    int[] next;
    cur = (int[]) data.elementAt(0);
    next = (int[]) data.elementAt(0);
    for (int i = 1; i < len; i++)
    {
        cur = next;
        next = (int[]) data.elementAt(i);
        g.drawLine(cur[0], cur[1], next[0], next[1]);
    }
    cur = (int[]) data.elementAt(0);
    g.drawLine(cur[0], cur[1], next[0], next[1]);
 }

 public void loadFile (String name)
 {
    data = new Vector();
    int x,y;
    int[] cur;
    String st;
   
    try {
        FileInputStream is = new FileInputStream(name);
        StreamTokenizer t = new StreamTokenizer(is);
        t.whitespaceChars(',', ',');
        while (true) {
       
            if (t.nextToken() == StreamTokenizer.TT_EOF) return;
    //        st = t.sval;
            x = (int) t.nval;
            System.out.println("\nnext token = " + x);
            if (t.nextToken() == StreamTokenizer.TT_EOF) return;
            y = (int)t.nval;
            System.out.println("\nnext token = " + y);
            cur = new int[2];
            cur[0] = x;
            cur[1] = y;
            data.addElement(cur);    
        }
    } catch (Exception e )
    {
        System.out.println("Error caught");
        e.printStackTrace();
    }
 }

public static void main (String[] args) {
    Frame f = new Frame();
    f.setLayout(new BorderLayout());
    PaintTest test = new PaintTest();
    test.loadFile("c:\\data.txt");

    f.add(test , BorderLayout.CENTER);
    f.setSize(150,150);
    f.addWindowListener(
    new WindowAdapter() {
        public void windowClosing(WindowEvent e) {
            System.exit(0);
        }
    }
    );
//    f.pack();
    f.show();

}
}
--- end

hope this helps
  heyhey

P.S. if you need more information on applets post a question here
 
0
 
robjayAuthor Commented:
This looks like the right direction - but I definately need to get this to the web browser -
(you can look at my attempt at http://www.clearsail.net/~robjay/Graph3Applet.java)
a gif would be OK, but presentation in an applet would be better - can you explain a little
more how I can do this in an applet or my best alternative?
Thanks

0
 
robjayAuthor Commented:
As I have looked at this a little more, could you write the exact code that you would use to replace this line, and say yourfile is out there at www.somewhere.com/data.txt :

FileInputStream is = new FileInputStream(name);

As I understand this, as long as my file is accessible via the internet, I can download the contents?


0
 
heyhey_Commented:
haven't tested it, but

URL url = new URL("www.somewhere.com/data.txt");
InputStream = URL.getStream();

should work. Your browser sends HTTP reuqest to the web-server at www.somewhere.com, handles the response and gives you only the body of the message (which is your data.txt file)
0
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

Join & Write a Comment

Featured Post

Cloud Class® Course: Microsoft Azure 2017

Azure has a changed a lot since it was originally introduce by adding new services and features. Do you know everything you need to about Azure? This course will teach you about the Azure App Service, monitoring and application insights, DevOps, and Team Services.

  • 2
  • 2
Tackle projects and never again get stuck behind a technical roadblock.
Join Now