Membaca string yang tersimpan dalam file

public static String readFile (String alamatfile) throws FileNotFoundException{
File file = new File(alamatfile);

FileInputStream fis = new FileInputStream(file);
ByteArrayOutputStream bos = new ByteArrayOutputStream();
byte[] buf = new byte[1024];
try {
for (int readNum; (readNum = fis.read(buf)) != -1;) {
bos.write(buf, 0, readNum);
}
} catch (Exception ex) {
ex.getMessage();
}
String isi = bos.toString();

return isi;
}