What is the proper way to use the write method?

Question

What is the proper way to use the OutputStreams write method? I know the flush() method is automatically called after the write but i cant seem to get any output
to a file. The char array contains characters and upon completion of the for loop the contents of the array is printed out, so there is actually data in the array. But write dosnt seem to do squat no matter what i seem to do. Any suggestions?
import java.io.*;
public class X{
public static void main(String[] args){
try{      
FileReader fis = new FileReader("C:\\Java\\Test.txt"); //read chars
FileWriter fw = new FileWriter("C:\\Java\\Test1.txt"); //read chars
File f = new File("C:\\Java\\Test.txt");
char[] charsRead = new char[(int)f.length()];
while(true){
int i = fis.read(charsRead);
if(i == -1) break;
// fw.write(charsRead); this wont work
// but there is infact chars in the char Array?
for(int i = 0; i < charsRead.length -1 ; ++i){
System.out.print(charRead);
}catch(Exception e){System.err.println(e);}

Answer 1

Sorry to have to tell you this guys but all of the above are broken.
First of all... you should all take a good look at what the read() method actually does.
http://java.sun.com/j2se/1.3/docs/api/java/io/InputStream.html#read(byte[], int, int)
Pay special attension to this paragraph:
Reads up to len[i] bytes of data from the input stream into an array of bytes. An attempt is made to read as many as len[i] bytes, but a smaller number may be read, possibly zero. The number of bytes actually read is returned as an integer.
In other words... when you use read() and you request say 1024 bytes, you are not guaranteed to get that many bytes. You may get less. You may even get none at all.
Supposing you want to read length bytes from a stream into a byte array, here is how you do it.int bytesRead = 0;
int readLast = 0;
byte[] array = new byte[length];
while(readLast != -1 && bytesRead < length){
  readLast = inputStream.read(array, bytesRead, length - bytesRead);
  if(readLast != -1){
    bytesRead += readLast;
}And then the matter of write()...
http://java.sun.com/j2se/1.3/docs/api/java/io/OutputStream.html#write(byte[])
write(byte[] b) will always attempt to write b.length bytes, no matter how many bytes you actually filled it with. All you C/C++ converts... forget all about null terminated arrays. That doesn't exist here. Even if you only read 2 bytes into a 1024 byte array, write() will output 1024 bytes if you pass that array to it.
You need to keep track of how many bytes you actually filled the array with and if that number is less than the size of the array you'll need pass this as an argument.
I'll make another post about this... once and for all.
/Michael