golmschenk golmschenk - 1 year ago 90
Java Question

BufferedWriter not writing everything to its output file

I have a Java program that reads some text from a file, line by line, and writes new text to an output file. But not all the text I write to my

appears in the output file after the program has finished. Why is that?

The details: the program takes a CSV text document and converts it into SQL commands to insert the data into a table. The text file has more than 10000 lines which look similar to following:


The program seems to work fine except it just stops in the file randomly half way through creating a new SQL statement having printed it into the SQL file. It looks something like:

insert into nyccrash values (2007, 1, 2, 1, 4, 1033092, 259916);
insert into nyccrash values (2007, 1, 1, 1, 1, 1020246, 197687);
insert into nyccrash values (2007, 10, 9, 1

This happens after about 10000 lines but several hundred lines before the end of the file. Where the break happens is between a
and a
. However, the characters doesn't seem important because if I change the
to a
the last thing written to the new file is
, which is cutting off the 2 from that integer. So it seems like the reader or writer must just be dying after writing/reading a certain amount.

My Java code is as follows:

import java.io.*;

public class InsertCrashData
public static void main (String args[])
//Open the input file.
FileReader istream = new FileReader("nyccrash.txt");
BufferedReader in = new BufferedReader(istream);
//Open the output file.
FileWriter ostream = new FileWriter("nyccrash.sql");
BufferedWriter out = new BufferedWriter(ostream);
String line, sqlstr;

sqlstr = "CREATE TABLE nyccrash (crash_year integer, accident_type integer, collision_type integer, weather_condition integer, light_condition integer, x_coordinate integer, y_coordinate integer);\n\n";

while((line = in.readLine())!= null)
String[] esa = line.split(",");
sqlstr = "insert into nyccrash values ("+esa[0]+", "+esa[1]+", "+esa[2]+", "+esa[3]+", "+esa[4]+", "+esa[5]+", "+esa[6]+");\n";
catch(Exception e)

Answer Source

You need to close your OutputStream which will flush the remainder of your data:


The default buffer size for BufferedWriter is 8192 characters, large enough to easily hold hundreds of lines of unwritten data.

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