java.io.FileNotFoundException when reading .csv file

Question

I'm supposed to create a java applet project and in that I need to read data from .csv file and put it in a scrollable table. I tried to dothat and i get a FileNotFoundException exception.

Here is my code:

import java.applet.Applet;
import java.awt.BorderLayout;
import java.io.BufferedReader;
import java.io.FileReader;
import java.util.ArrayList;

import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;

@SuppressWarnings("serial")
public class Test extends Applet
{  
   Table table;
   public void init()
   {
      try
      {
         table = new Table();
      }
      catch (Exception e)
      {
         e.printStackTrace();
      }
      this.add(table);
   }
}



class Table extends JPanel
{
   private String[][] productList;
   private JTable table;

   public Table() throws Exception
   {
      read();
      BorderLayout layout = new BorderLayout();
      layout.addLayoutComponent(new JScrollPane(table), BorderLayout.CENTER);

      setLayout(layout);
   }

   private void read() throws Exception
   {
      ArrayList<String[]> list = new ArrayList<String[]>();
      try
      {
         BufferedReader br = new BufferedReader(new FileReader("Products.csv"));
         String line = br.readLine();

         while ((line = br.readLine()) != null)
         {
            String[] toBeAdded = line.split(",");
            list.add(toBeAdded);
         }
      }
      catch (Exception e)
      {
         e.printStackTrace();
      }

      productList = new String[list.size()][3];
      for (int i = 0; i < productList.length; i++)
         for (int j = 0; j < productList[i].length; j++)
            productList[i][j] = list.get(i)[j];
   }
}

The products.csv is there in the root folder. I try to read in a normal non swing project and it works but not for this. Can anyone help me?

Powerlord · Accepted Answer · 2014-11-01 00:03:13Z

1

I can think of two potential problems:

An applet can't read files located on the web server.
If the file is packed inside a jar file, you need special code in order to read it. Specifically, you need a ClassLoader's getResourceAsStream.

For the second, the easiest way to get the ClassLoader's getResourceAsStream is to call Class's getResourceAsStream.

I haven't tested it, but something like this should work:

BufferedReader br = new BufferedReader(new InputStreamReader(Table.class.getResourceAsStream("/Products.csv")));

If that doesn't compile, change Table.class to this.getClass()

Note that the / is there to indicate that Products.csv is at the root of the .jar file. Otherwise, it will use the package name as a directory to look in (i.e. if the package was package this.is.my.boomstick;, it'd try to open this/is/my/boomstick/Products.csv)

edited Nov 1, 2014 at 0:03

answered Oct 31, 2014 at 23:50

Powerlord

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5 Comments

Hridayam Bakshi Over a year ago

I tried it and it says that there is no such constructor BufferedReader(InputStream)

Powerlord Over a year ago

@HridayamBakshi Right, my mistake... you need to wrap it in an InputStreamReader first... I'll fix my answer in a second. Edit: Should be fixed now.

Hridayam Bakshi Over a year ago

It is throwing a NullPointerException now

Powerlord Over a year ago

@AndrewThompson Well, the NPE is likely because Table.class.getResourceAsStream isn't finding the file in question, which would mean this answer is in some form wrong.

Andrew Thompson Over a year ago

As far as I am concerned, the question was well answered in the suggestion to change from using a File, which will not work with an applet (especially not with a resource on the server!). Too often you get these things dragging on until the OP has successfully (loaded the resource and) deployed the applet - help desk style. My aim is to convince people to recognize that one task 'deploy applet successfully' is actually made up of many small steps. All said of course, 'IMO'. (+1 for your answer, BTW.)

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