What's wrong with the program?

[Niyas Ahmed Sheikh]

import java.io.*;
class FileInputStreamEx
{
  public static void main(String args[]) throws IOException
  {
      FileInputStream fis = new FileInputStream("b.txt");
      byte bb[] = new byte[10];
       
      for(int i = 0; i < 10; i++)
      {  
         fis.read(bb);
         System.out.print((char)bb[i]);
      }
  }
}  

b.txt
-----
abcdefghij

output:
------
a
defghij

In the above pgm, the byte array bb[0] - bb[9] will have a - j.
But I got the above output. I thought the output should be: abcdefghij

What's wrong with the program?

[Jesper de Jong]

Take fis.read(bb) out of the loop.

import java.io.*;
class FileInputStreamEx
{
  public static void main(String args[]) throws IOException
  {
      FileInputStream fis = new FileInputStream("b.txt");
      byte bb[] = new byte[10];
       
      fis.read(bb);
 
      for(int i = 0; i < 10; i++)
      {  
         System.out.print((char)bb[i]);
      }
  }
}

[Manuel Moons]

The read(byte[]) command will try to read 10 bytes at once (because your byte[] is 10 bytes). It will try to read those 10 bytes and when the inputstream is at it's end it will return -1. If less then 10 bytes can be read the read method will return the amount that can be read.

So if you follow these rules you can see why your output can be unpredictable.

You'd better do something like this:

FileInputStream fis = new FileInputStream("b.txt");
byte bb[] = new byte[10];
 
int amount_read = 0;
while((amount_read = fis.read(bb)) != -1) {
  for(int i = 0; i < amount_read; i++) {
     System.out.print((char)bb[i]);
  }
}

[Choon-Chern Lim]

Instead of reading character by character, consider using bufferedReader to read the whole line.

  
try {
BufferedReader rd = new BufferedReader(new FileReader("c:\\a.txt"));
String s = "";
 
while ((s = rd.readLine()) != null) {
System.out.println(s);
}
rd.close();
}
catch (IOException e) {}