BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream("test.txt")));
Map<String, List<String>> map = new HashMap<String, List<String>>();
String buf;
while ((buf=br.readLine()) != null) {
    String[] v = buf.split(":", 2);
    if (!map.containsKey(v[0])) {
        map.put(v[0], new LinkedList<String>());
    }
    map.get(v[0]).add(v[1]);
}
br.close();
System.out.println(map);