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Java FileWriter Class - GeeksforGeeks

Last Updated : 23 Jul, 2025

Java FileWriter class of the java.io package is used to write data in character form to a file. The FileWriter class in Java is used to write character-oriented data to a file. It is a character-oriented class that is used for file handling in Java.

• This Class inherits from OutputStreamWriter class which in turn inherits from the Writer class.
• The Constructors of this class assume that the default character encoding and the default byte-buffer size are acceptable. To specify these values yourself, construct an OutputStreamWriter on a FileOutputStream.
• FileWriter is meant for writing streams of characters. For writing streams of raw bytes, consider using a FileOutputStream.
• FileWriter creates the output file if it is not present already.

FileWriter extends OutputStreamWriter and Writer classes. It implements the following interfaces:

• Closeable
• Flushable
• Appendable
• AutoCloseable

public class FileWriter extends OutputStreamWriter 

Constructor

Description

FileWriter(File file)

It constructs a FileWriter object given a File object. It throws an IOException if the file exists but is a directory rather than a regular file does not exist but cannot be created, or cannot be opened for any other reason.

FileWriter(File file, boolean append)

It constructs a FileWriter object given a File object. If the second argument is true, then bytes will be written to the end of the file rather than the beginning. It throws an IOException if the file exists but is a directory rather than a regular file or does not exist but cannot be created, or cannot be opened for any other reason.

FileWriter(FileDescriptor fd)

It constructs a FileWriter object associated with a file descriptor.

FileWriter(File file, Charset charset)

It constructs the fileWriter when file and charset is given.

FileWriter(File file, Charset charset, boolean append)

It constructs the fileWriter when file and charset is given and a boolean indicating whether to append the data written or not.

FileWriter(String fileName)

It constructs a FileWriter object given a file name.

FileWriter(String fileName, Boolean append)

It constructs a FileWriter object given a file name with a Boolean indicating whether or not to append the data written.

FileWriter(String fileName, Charset charset)

It constructs a FileWriter when a fileName and charset is given.

FileWriter(String fileName, Charset charset, boolean append)

It constructs a fileWriter when a fileName and a charset are given and a boolean variable indicating whether to append data or not.

Example 1: Writing Characters to a File using FileWriter class

// Writing Characters in File using FileWriter
import java.io.FileWriter;
import java.io.IOException;
import java.util.*;

class WriteFile
{
    public static void main (String[] args)
    {
      	// Scanner Class Instance
        Scanner scn=new Scanner(System.in);
      	
      	// User input for the File Path
      	String path=scn.nextLine();

      	// Writing in File
        try (FileWriter writer = new FileWriter(path)) 
        {
            String str= "Hello Geeks!\nThis is about Programming";
            writer.write(str);

            System.out.println("Data written to the file successfully.");
        
        } 
     
      	// Exception Thrown 
      	catch (IOException e) {
            System.out.println("An error occurred while writing"
                               + " to the file: " + e.getMessage());
        }
      
    }
}

Output:

Example 2: Appending Data to a File

// Appending Data to a File
import java.io.*;

class AppendingFile 
{
    public static void main (String[] args) 
    {
      	// Appending Data in the File
       	try (FileWriter writer = new FileWriter(fileName, true)) { 
          	
          	// true for append mode
          	writer.write("\nAppending this line to the file.");
          	System.out.println("Data appended to the file successfully.");
		} 
      	catch (IOException e) {
    		System.out.println("An error occurred while appending"
                               + " to the file: " + e.getMessage());
		}
    }
}

Output:

Method                                         

void write(int a)

Writes a single character specified by an Integer value.

void write(String str, int pos, int length)

Writes a portion of the string from position pos until the length number of characters.

void write(char ch[], int pos, int length)

Writes the position of characters from array ch[] from position pos till length number of characters.

int getEncoding()

Returns the character encoding used by FileWriter.

Method                                                      

Overwriting a File: While creating a Java FileWriter, we can decide whether we want to append the file to an existing file, or we want to overwrite any existing file. This can be decided by choosing the appropriate constructor. The constructor for overwriting any existing file takes only one parameter that is a file name.

Writer fileWriter = new FileWriter("C:\\FileHandling\\FileDescriptor\\FILE.txt");

Appending to a File: The constructor for appending the file or overwriting the file, takes two parameters, the file name and a boolean variable which decides whether to append or overwrite the file

Writer fileWriter = new FileWriter("C:\\FileHandling\\FileDescriptor\\FILE.txt", true); // appends to file
Writer fileWriter = new FileWriter(C:\\FileHandling\\FileDescriptor\\FILE.txt", false); // overwrites file

• FileWriter writes streams of characters while FileOutputStream is meant for writing streams of raw bytes.
• FileWriter deals with the character of 16 bits while on the other hand, FileOutputStream deals with 8-bit bytes.
• FileWriter handles Unicode strings while FileOutputStream writes bytes to a file and it does not accept characters or strings and therefore for accepting strings, it needs to be wrapped up with OutputStreamWriter. string.

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