Reading from file

[Marc Kryzhan]

I've successfully read from a file; proven because I wrote to a text file by copying from a file. How do I do a System.out.println of the contents of a file? Here's my code that I used to write a file and inwhich I've also attempted to output the encoded contents of my file with println. The file I read from is called farrago.txt (from sun's site). I modified it to contain two lines of text.
import java.io.*;
public class Copy {
public static void main(String[] args) throws IOException {
File inputFile = new File("farrago.txt");
File outputFile = new File("outagain.txt");
FileReader in = new FileReader(inputFile);
FileWriter out = new FileWriter(outputFile);
int c;
while ((c = in.read()) != -1)
{out.write(c);
System.out.println("ToString " + out.toString());
System.out.println("Read " + in.read());
System.out.println("Encoding " + in.getEncoding());
System.out.println("Can Read? " + inputFile.canRead());
System.out.println("Path " + inputFile.getPath());
System.out.println("Length " + inputFile.length());

//System.out.println("..." + getEncoding();
}
in.close();
out.close();
}
}

[Tim West]

Hi Marc,
in.read() returns an int - the character code of the char you read. You need to cast this to a char when printing out.
With minimal changes to your code, this works:

import java.io.*;
public class A {
    public static void main(String[] args) throws IOException {
        File inputFile = new File("C:\\SQL.txt");
        File outputFile = new File("C:\\SQL2.txt");
        FileReader in = new FileReader(inputFile);
        FileWriter out = new FileWriter(outputFile);
        /* Could shorten this to:
           FileReader in = new FileReader("C:\\foo.txt");
           FileWriter out = new FileWriter("C:\\bar.txt");
         */
        int c;
        while ((c = in.read()) != -1) {
            out.write((char)c);
            out.flush();
        }
        in.close();
        out.close();
    }
}

However, you'll find that I/O in Java can be made much easier (or more complicated, depending on your point of view) by combining the various classes available for reading and writing.
Thus some equivalent code is:

import java.io.*;
public class A {
    public static void main(String[] args) throws IOException {
        BufferedReader in = new BufferedReader(
                                new FileReader("C:\\SQL.txt"));
        PrintWriter out = new PrintWriter(
                                new FileWriter("C:\\SQL2.txt"));
        
        while (in.ready()) {
            out.print(in.readLine());
        }
        in.close();
        out.close();
    }
}

The advantage of the code above is that you get a whole line at a time - this is often very useful. Other classes are available for reading from zip files, from sockets, from just about anything...and writing back. :-)
Cheers,
--Tim
[ March 29, 2004: Message edited by: Tim West ]

[Nathaniel Stoddard]

You can read the contents of the file into a buffer of bytes (ie byte[]) and then just System.out.print(buffer), over and over until you reach the end of the file. Is that what you are thinking?

[Dirk Schreckmann]

Moving this to the I/O and Streams forum...
[ March 29, 2004: Message edited by: Dirk Schreckmann ]