Java IOException - Stream Closed

Question

I get "IOException: Stream Closed" when I run this program. The text contains many lines of data. Program should read each line, do necessary function and write the output to a new file. I am confused as to which writer should be closed first and where.

import java.net.*; 
import java.io.*;

public class URLReader {
    public static void main(String[] args) throws Exception {
        BufferedReader br = null;
        try {
            // change this value
            FileInputStream fis = new FileInputStream("C:\\Users\\Rao\\Desktop\\test.txt");
            br = new BufferedReader(new InputStreamReader(fis, "UTF-8"));
            String sCurrentLine;
            while ((sCurrentLine = br.readLine()) != null) {
                processLine(sCurrentLine); //error
            }
        } finally {
            if (br != null)
                br.close();
        }
    }

    public static void processLine(String line) throws IOException {
        String prename = line.substring(22);
        int siz= prename.indexOf(":");
        String name = prename.substring(0, siz);

        URL oracle = new URL("http://ip-api.com/json/"+name);
        BufferedReader in = new BufferedReader(new InputStreamReader(oracle.openStream()));
        String inputLine;
        while ((inputLine = in.readLine()) != null) // error
            // System.out.println(inputLine);
            in.close();  
        String baby = (line + "\t" + inputLine); 

        try {
            FileWriter writer = new FileWriter("C:\\Users\\Rao\\Desktop\\output.txt", true);
            writer.write(baby);
            writer.write("\r\n");   // write new line
            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

The exception is as follows:

Exception in thread "main" java.io.IOException: Stream closed
    at java.io.BufferedReader.ensureOpen(Unknown Source)
    at java.io.BufferedReader.readLine(Unknown Source)
    at java.io.BufferedReader.readLine(Unknown Source)
    at URLReader.processLine(URLReader.java:31)
    at URLReader.main(URLReader.java:13)

what's the value of name when the exception is thrown ? doest the url really exists with this name ? what's the response ? — vincent
– vincent, Commented Oct 5, 2015 at 8:13
Did you mean to put an empty statement after while ((inputLine = in.readLine()) != null)? Right now you have effectively while ((inputLine = in.readLine()) != null) {in.close();} — Stack Exchange Broke The Law
– Stack Exchange Broke The Law, Commented Oct 5, 2015 at 8:15
I had closed it before I could write another. Thanks to Jens, It is fixed. Thanks guys — Scitech
– Scitech, Commented Oct 5, 2015 at 8:21

Jens · Accepted Answer · 2015-10-05 08:13:56Z

7

You close the input stream in your loop:

while ((inputLine = in.readLine()) != null) // error

               // System.out.println(inputLine);
in.close();

You should close the stream outside of the loop:

while ((inputLine = in.readLine()) != null) // error
{
   //dosomething
   // System.out.println(inputLine);
}
in.close();

answered Oct 5, 2015 at 8:13

Jens

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Comments

morels · Accepted Answer · 2015-10-05 08:26:36Z

You should put a function call in the while loop, like:

a System.out.println("Hi, I'm a row!"); or
uncomment System.out.println(inputLine); or
put a semicolon at the end of the while statement

in order to let it to execute properly.

The code as it is written executes (comments omitted):

...
   while ((inputLine = in.readLine()) != null)
     in.close();  
...

so the first cycle of the loop executes correctly and runs in.close(). Then the second cycle the call inputLine = in.readLine() fails because the stream is closed and then the exception is thrown.

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