readText
- Kotlin course
- Intermediate
- Lesson 95/116
- 5 min
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 "ö" instead of "ö"). So it is a good habit to specify the encoding explicitly. Calling readText() with no argument assumes UTF-8.
Practice 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.
Starter code
import java.io.File
// File object for path not.txt
// write "Hello Kotlin" to it
// read with readText and println
fun main() {
// write here
}Sample solution
fun main() {
val f = File("not.txt")
f.writeText("Hello Kotlin")
println(f.readText())
}Expected output
Hello Kotlin
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Read the file
val content = f.____()val content = f.readText()Explanation: readText reads all content as a single string.
2 Match the readText concepts
| Term | Meaning |
|---|---|
readText() |
Reads all content |
String |
Return type |
UTF-8 |
Default encoding |
\n |
Line break |
3 What type does readText() return?
- List<String>
- String Correct answer
- ByteArray
- Int
Explanation: readText returns all content as a single String.