kotlin-stdlib / kotlin.io / java.io.File / useLines useLines JVM 1.0 inline fun < T > File . useLines ( charset : Charset = Charsets.UTF_8 , block : ( Sequence < String > ) -> T ) : T (source) Calls the block callback giving it a sequence of all the lines in this file and closes the reader once the processing is complete. Parameters charset - character set to use. By default uses UTF-8 charset. Return the value returned by block .