import java.io.BufferedWriter;
import java.io.IOException;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

public class App {    
    public static void writeFile() {
        try {
            tryWriteFile();
        } catch (IOException e) {
            System.err.println("Hiba! A fájl nem olvasható!");
        }
    }
    public static void tryWriteFile() throws IOException {
        Path path = Paths.get("adat.txt");
        Charset cs = StandardCharsets.UTF_8;
        
        BufferedWriter writer = Files.newBufferedWriter(path, cs);
        writer.write("Valami");
        writer.close();
        
    }

    public static void main(String[] args) throws Exception {
        writeFile();
    }
}