How to append when writing to a text file in a Java or Scala application

By Alvin Alexander. Last updated: March 19, 2024

As a quick Scala/Java tip, to append to a file when writing to a text file in a Scala or Java application, create your FileWriter with the append flag set to true, like this:

val bw = new BufferedWriter(new FileWriter(new File("/tmp/file.out"), true))  // <-- 'true'
bw.write("Hello, world\n")
bw.close

FileWriter takes two arguments, so that code might be easier to read when it’s formatted like this:

val bw = new BufferedWriter(
    new FileWriter(
        new File("/tmp/file.out"),
        true
    )
)
bw.write("Hello, world\n")
bw.close

Note: Appending to a text file with Scala 3

As a quick update, a great thing about Scala 3 is that you can get rid of all those new keywords, so the first part of that last example looks like this in Scala 3:

val bw = BufferedWriter(
    FileWriter(
        File("/tmp/file.out"),
        true
    )
)

scala