BufferedReader br = new BufferedReader(new FileReader("file.txt"));
try {
    StringBuilder sb = new StringBuilder();
    String line = br.readLine();
    while (line != null) {
        sb.append(line);
        sb.append(System.lineSeparator());
        line = br.readLine();
    }
    String text= sb.toString();
    String parts = text.split(":")
    String id= parts[0]
    String username = parts[1]
    String pass = parts[2]
} finally {
    br.close();
}