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

Append to File using Files class

With Files class, we can write a file using it’s write() function. Internally write() function uses OutputStream to write byte array into the 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
}

Append to File using BufferedWritter

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

To append string to an existing file, open file writer in append mode with passing the second argument as true.

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

	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 the 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();
}

Happy Learning !!