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Basic File Reading

  Asked By: Michael    Date: Aug 29    Category: Java    Views: 816
  

I am working on a program that read in a text file. Below is the
code that I am currently using
-------------------
public void load_file()
{
FileReader fp;
char[] reading_buffer = new char[1024];

try
{
fp = new FileReader(new File(file_name));
while (fp.read(reading_buffer) != -1)
{
buffer += new String(reading_buffer);
}
}
catch(IOException event)
{
System.exit(0);
}
}
-----------------------
file_name (protected String file_name) and buffer (protected String
buffer) are class member.
-----------------------
For the most part this works, but if the file is not a 1024*x bytes
in size, the end of buffer will contain unknown character (stuff not
in the file) to make the length of reading_buffer 1024*x bytes.

Why do I get this garbage character?

I am mostly a C/C++ programmer, so I am sure there is a more
efficient way to accomplish this, but I don't know what it is, this
just seemed the most normal (comeing from a C/C++ point of view).
Can anyone tell me a better way to accomplish this?

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4 Answers Found

 
Answer #1    Answered By: Hubert Taylor     Answered On: Aug 29

The read  method returns how many characters it read before it reached the end  of
file. So, I don't see how the garbage character  should be a problem. In fact,
your garbage  character may just be an end of file  character.

 
Answer #2    Answered By: Lurlene Fischer     Answered On: Aug 29

here is a perfect collection of code snippets:
http://www.javaalmanac.com/
You will find a solution to your problem there as well.
This URL is always a good stop when having these "simple" problems.

 
Answer #3    Answered By: Helene Stewart     Answered On: Aug 29

Try using the code below. I cut it out of a program  I wrote. What
you are failing to catch in your code is the number of characters
returned by the read() method. Also notice that I am only putting the
number of characters returned by read() into the StringBuffer. This
ensures that no extra characters are put into the resulting string.
Also because I am using a StringBuffer instead of string  this code
should execute a bit faster than yours.


final int BUFSIZE = 1024;
String infile = "xxxxxxx";


StringBuffer inbuf = new StringBuffer();
try {
FileReader fr = new FileReader(infile);
char c[] = new char[BUFSIZE];
int cnt = 0;
while ((cnt = fr.read(c, 0, BUFSIZE)) >= 0) {
if (cnt > 0) {
inbuf.append(c, 0, cnt);
}
}
fr.close();
} catch (FileNotFoundException fnfe) {
System.err.println("File '" + infile + "' not found.");
} catch (IOException ioe) {
System.err.println("Error reading  '" + infile + "'.");
}

 
Answer #4    Answered By: Feodora Bonkob     Answered On: Aug 29

That fixed my problem, and I actually do notice a
significant preformance improvement (I am working  with fairly large
file).

 
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