In my previous posts I talked about how to Create and Delete
files using Java. Now, once you have created a file the next step is to
write some content in those files and that can be achieved by using:
- BufferedWriter, or
FileWriter writer = new FileWriter(fileToWriteIn);
BufferedWriter bufferedWriter = new BufferedWriter(writer);
bufferedWriter.write(toWrite);
bufferedWriter.close();
- FileOutputStream.
FileOutputStream stream = new FileOutputStream(fileToWriteIn);
stream.write(toWrite.getBytes());
stream.flush();
stream.close();
There are classes like FileWriter available
to perform write operation on a file but since writer sends its output
immediately to the underlying character or byte stream. So that is why
until prompt output is required, it is recommended to wrap a
BufferedWriter around it.
Here is an example with full code and main method:
package home.flicker.java.io.file;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Scanner;
public class WriteInFile {
File file = null;
/**
* Method to create a file with the given name.
*/
public boolean createFile(String fileName) {
boolean result = false;
file = new File(fileName);
// creating the new File. The Method createNewFile() returns TRUE if file is successfully created else it returns FALSE.
try {
result = file.createNewFile();
} catch (IOException e) {
System.err.println("Error while creating file!!! " + e.getMessage());
}
return result;
}
/**
* Method to read content from user and write it in given file using BufferedReader.
*/
public boolean writeInFileWithBufferedWriter(File fileToWriteIn){
boolean result = false;
String toWrite = readFromUser("Data to write");
try {
FileWriter writer = new FileWriter(fileToWriteIn);
BufferedWriter bufferedWriter = new BufferedWriter(writer);
bufferedWriter.write(toWrite);
bufferedWriter.close();
result = true;
} catch (IOException e) {
System.err.println("Error while writing in file!!! " + e.getMessage());
}
return result;
}
/**
* Method to read content from user and write it in given file using FileOutputStream.
*/
public boolean writeInFileWithFileOutputStream(File fileToWriteIn) {
boolean result = false;
String toWrite = readFromUser("Data to write");
try {
FileOutputStream stream = new FileOutputStream(fileToWriteIn);
stream.write(toWrite.getBytes());
stream.flush();
stream.close();
result = true;
} catch (FileNotFoundException e) {
System.err.println("Error: File not found!!! How the hell I am supossed to write :P " + e.getMessage());
} catch (IOException e) {
System.err.println("Error while writing in file!!! It's stupid x( " + e.getMessage());
}
return result;
}
/**
* Reads input from user as string and puts the label as question.
*/
public static String readFromUser(String label) {
Scanner scanner = new Scanner(System.in);
System.out.println(label + ": ");
String input = scanner.next();
return input;
}
/**
* Main method.
*/
public static void main(String args[]) throws IOException{
WriteInFile example = new WriteInFile();
String fileName = readFromUser("Enter File name");
example.createFile(fileName);
example.writeInFileWithBufferedWriter(example.file);
example.writeInFileWithFileOutputStream(example.file);
}
}
The
thing with these methods is that they over-write the content which is
already in the file. To avoid that you need to append data. Will cover
that some other time.
I hope this post helps you. Share your experience or issues...
