Java Write To File - Java Tutorial

Introduction
In the section, you will learn how to write data to a file. As we have discussed, the FileOutputStream class is used to write data to a file. 
Lets see an example that writes the data to a file converting into the bytes.
This program first check the existence of the specified file. If the file exist, the data is written to the file through the object
of the FileOutputStream class.

import java.io.*;

public class WriteFile{

    public static void main(String[] args) throws IOException{

      File f=new File("textfile1.txt");
      FileOutputStream fop=new FileOutputStream(f);

      if(f.exists()){
      String str="This data is written through the program";
          fop.write(str.getBytes());

          fop.flush();
          fop.close();
          System.out.println("The data has been written");
          }

          else
            System.out.println("This file is not exist");
    }
  }

Output of the Program 

C:\nisha>javac WriteFile.java C:\nisha>java WriteFile The data has been written C:\nisha>

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The another way for writing data to a file, the class FileWriter and BufferedWriter are used.
 FileWriter :
 FileWriter is a subclass of OutputStreamWriter class that is used to write text (as opposed to binary data) to a file. You create a FileWriter by specifying the file to be written to, or optionally, when the data should be appended to the end of an existing file instead of overwriting that file. The FileWriter class creates an internal FileOutputStream to write bytes to the specified file
BufferedWriter :
The BufferedWriter class is used to write text to a character-output stream, buffering characters so as to provide for the efficient writing of single characters, arrays and strings.
The constructor of the FileWriter class takes the file name which has to be buffered by the BufferedWriter stream. The write( ) method of BufferedWriter class is used to create the file into specified directory.
Following code  write data into new file: 
out.write(read_the_Buffered_file_name);
Following code creates the object of FileWriter and BufferedWriter: 

FileWriter fstream = new FileWriter(file_name); BufferedWriter out = new BufferedWriter(fstream);

Lets see an another example that writes the text input by the user using the FileWriter and the BufferedWriter class.

import java.io.*;

public class FileWriter{

  public static void main(String[] args) throws IOException{
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    System.out.print("Please enter the file name to create : ");
    String file_name = in.readLine();
    File file = new File(file_name);
    boolean exist = file.createNewFile();
    if (!exist)
    {
      System.out.println("File already exists.");
      System.exit(0);
    }
    else
    {
      FileWriter fstream = new FileWriter(file_name);
      BufferedWriter out = new BufferedWriter(fstream);
      out.write(in.readLine());
      out.close();
      System.out.println("File created successfully.");
    }
  }
}

Output of the Program 

C:\nisha>javac CreateFile.java C:\nisha>java CreateFile Please enter the file name to create : nishu.txt this is my name File created successfully. C:\nisha>

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