Read and Write Files in Java

Here is a sample code I just wrote. This class copies one file to another.
By understanding this code below , you will comphrend both reading from and writing to file concepts in java. I used FileInputStream and FileOutputStream in this code.

package javacream;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class FileUtil {

public static void copyFile(String strInputFileName , String strOutputFileName) throws IOException {

//Prepare file objects

File fInputFile = new File(strInputFileName);

File fOutputFile = new File(strOutputFileName);

//Prepare read write streams from file objects

FileInputStream fis = new FileInputStream(fInputFile);

FileOutputStream fos = new FileOutputStream(fOutputFile);

int c;

// read from the input file and write to the output file

while ((c = fis.read()) != -1) {

fos.write(c);

}

//we are done , close the streams.

fis.close();

fos.close();

}

public static void main(String[] args) {

try {

// use \\ for windows filenames , otherwise use single /

copyFile("d:\\sample.txt", "d:\\copyof_sample.txt");

} catch (IOException e) {

e.printStackTrace();

}

}

}

Alternatively , you can use FileReader object and BufferedReader. The sample code below counts the number of lines of a given file.

public static int lineCount(String fileName) throws IOException{

// file reader to read the file

FileReader input = new FileReader(fileName);

// Filter FileReader through a BufferedReader to read line by line

BufferedReader bufRead = new BufferedReader(input);

String line; // String that holds current file line

int count = 0; // Line count

// Read first line

line = bufRead.readLine();

count++;

// Read through file one line at time.

while (line != null){

line = bufRead.readLine();

count++;

}

bufRead.close();

return count;

}