gistfile1.txt

// 1. Create text file with windows-1251 (or any other non-utf8 encoding) - source.txt

// 2. Execute that code

val sourceContent = File("source.txt").readText(Charset.forName("windows-1251"))
File("utf8.txt").writeText(String(sourceContent.toByteArray()))

// 3. Check utf8.txt file and you'll see text file with utf-8 encoding

For example sample text in russian windows-1251: а вот и текст


Source file in hex (source.txt):

E0 20 E2 EE F2 20 E8 20 F2 E5 EA F1 F2 0A

After this code execution:

D0 B0 20 D0 B2 D0 BE D1 82 20 D0 B8 20 D1 82 D0 B5 D0 BA D1 81 D1 82 0A