readText

Learn to read files with File.readText.

readText: Read the whole file

readText() returns the entire content of a file as a single String. Line breaks remain as \n characters inside the string. The default encoding is UTF-8; you can specify it with readText(Charsets.UTF_8).

val f = File("not.txt")
f.writeText("one\ntwo")
val content = f.readText()
println(content)

The output is a two-line text. readText suits small and medium files; it loads the whole content into memory. For very large files prefer readLines or useLines for line-by-line reading.

Encoding

Files are stored as byte arrays; text is converted to bytes through an encoding. In Kotlin the default encoding is UTF-8, which supports all Unicode characters including Turkish letters. Files from legacy systems may use ISO-8859-9 (for Turkish) or windows-1254.

val content = f.readText(Charsets.UTF_8)

If you use the wrong encoding, Turkish letters look broken (for example "Ã¶" instead of "ö"). So it is a good habit to specify the encoding explicitly. Calling readText() with no argument assumes UTF-8.

Exercise Write to a file and read with readText

Create val f = File("not.txt"). Write with f.writeText("Hello Kotlin"). Read and print with println(f.readText()). Add the import java.io.File import.

Show example solution

fun main() {
    val f = File("not.txt")
    f.writeText("Hello Kotlin")
    println(f.readText())
}

Test yourself

Read the file

val content = f.____()

Show answer

val content = f.readText()

Match the readText concepts

readText()

Reads all content
String

Return type
UTF-8

Default encoding
\n

Line break
What type does readText() return?
- List<String>
- String
- ByteArray
- Int
Show answer

String — readText returns all content as a single String.

Next lesson: writeText

We Are Enhancing Your Experience

Cookie Preferences

Strictly Necessary Cookies

Analytical Cookies