How to write a text file in Java

In the below examples, we are going to create text file (sample.txt) with below content.

Hello, it's a great day today!

Read text files using java.nio.Files utility class
Read text files using using java.io.FileWriter class
Read text files using using java.io.BufferedWriter class

using java.nio.Files

java.nio.Files is an utility class, which has lot of static methods that operate of files, in the below example we are going to use Files.writeString(Path, CharSequence) method which writes text content into the file, first argument to this method is Path where to write file, second argument is the String text that we want to write.

Note: Note that method is available since JDK 11.

public void writeToFileUsingFiles(String text, String fullyQualifiedPath) throws IOException { Files.writeString(Path.of(fullyQualifiedPath), text); }

You can also pass file OpenOption arguments to method, for example if you want to append the text to an existing file, then you can use as shown in below example, default behaviour is that it overrides the content.

Third parameter to method takes an optional array of . For the full list of File OpenOptions, read through this Java - File Open Options

public void writeToFileUsingFiles(String text, String fullyQualifiedPath) throws IOException { Files.writeString(Path.of(fullyQualifiedPath), text, StandardOpenOption.APPEND); }

using java.io.FileWriter

FileWriter class can be used to write text content into a file, and this is meant to be used for writing streams of characters only.

public void writeToFileUsingFileWriter(String text, String fullyQualifiedPath) throws IOException { try (FileWriter fileWriter = new FileWriter(fullyQualifiedPath)) { fileWriter.write(text); } }

In the above code, FileWriter.write(String) method writes input String into the file.

Default behaviour of above code is it always overrides the content. If you want to append text to the file instead, you can enable append=true at FileWriter level by using constructor as shown below. Below is the example code to append text.

public void appendToFileUsingFileWriter(String text, String fullyQualifiedPath) throws IOException { try (FileWriter fileWriter = new FileWriter(fullyQualifiedPath, true)) { fileWriter.write(text); } }

using java.io.BufferedWriter

BufferedWriter class expects another java.io.Writer type as an input argument to delegate the actual I/O operations to that.
BufferedWriter maintains a character array as a buffer in the memory to store chunks of characters data before writing to the actual file, it writes to the file once the buffer is filled and any remaining characters will be written when closing the writer at the end. (BufferedWriter is AutoClosable, using below syntax of try block, it automatically closes at the end of try block), thus minimizing number of I/O operations.

Note: Default buffer size is 16KB. You can change buffer size using constructor where 2^nd argument is the buffer characters array size.

BufferedWriter comes handy if you want to write data to files or sockets or to any other source and it is thread-safe (synchronized)

To obtain BufferedWriter instance, we could also use .

public void writeToFileUsingBufferedWriter(String text, String fullyQualifiedPath) throws IOException { try(BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(fullyQualifiedPath))) { bufferedWriter.write(text); } }

Above examples source code can be found at GitHub link for Java code and JUnit tests can be found at GitHub link for Unit tests code