Java – Append to File

Learn to append content to file in java using BufferedWritter, PrintWriter, FileOutputStream and Files class. In all the examples, while opening the file to write, you have pass a second argument as true which denotes that file is opened in append mode.

Table of Contents

Append to File using BufferedWritter
Append to File using PrintWriter
Append to File using FileOutputStream
Append to File using Files class

Append to File using BufferedWritter

BufferedWritter buffers before writing, so it result in less IO operations, so it improve the performance.

To append content to an existing file, open file writer in append mode by passing second argument as true.

public static void usingBufferedWritter() throws IOException 
{
	String textToAppend = "Happy Learning !!";
	
	BufferedWriter writer = new BufferedWriter(
								new FileWriter("c:/temp/samplefile.txt", true)	//Set true for append mode
							);	
	writer.newLine();	//Add new line
	writer.write(textToAppend);
	writer.close();
}

Append to File using PrintWriter

Use PrintWriter to write formatted text to a file. This class implements all of the print methods found in PrintStream, so you can use all formats which you use with System.out.println() statements.

To append content to an existing file, open file writer in append mode by passing second argument as true.

public static void usingPrintWriter() throws IOException 
{
	String textToAppend = "Happy Learning !!";
	
	FileWriter fileWriter = new FileWriter("c:/temp/samplefile.txt", true);	//Set true for append mode
    PrintWriter printWriter = new PrintWriter(fileWriter);
    printWriter.println(textToAppend);	//New line
    printWriter.close();
}

Append to File using FileOutputStream

Use FileOutputStream to write binary data to a file. FileOutputStream is meant for writing streams of raw bytes such as image data. For writing streams of characters, consider using FileWriter.

To append content to an existing file, open FileOutputStream in append mode by passing second argument as true.

public static void usingFileOutputStream() throws IOException 
{
	String textToAppend = "\r\n Happy Learning !!";	//new line in content
	
	FileOutputStream outputStream = new FileOutputStream("c:/temp/samplefile.txt", true);
    byte[] strToBytes = textToAppend.getBytes();
    outputStream.write(strToBytes);
 
    outputStream.close();
}

Append to File using Files class

With Files class, we can write a file using it’s write function, internally it’s using OutputStream to write byte array into file.

To append content to an existing file, Use StandardOpenOption.APPEND while writing the content.

public static void usingPath() throws IOException 
{
	String textToAppend = "\r\n Happy Learning !!";	//new line in content
	
	Path path = Paths.get("c:/temp/samplefile.txt");
 
    Files.write(path, textToAppend.getBytes(), StandardOpenOption.APPEND);	//Append mode
}

Happy Learning !!