gistfile1.java

		Map<String, Integer> sources = new HashMap<String, Integer>();
		Map<Integer, ArrayList<String>> results = new HashMap<Integer, ArrayList<String>>();

		sources.put("a", 1);
		sources.put("b", 3);
		sources.put("c", 5);
		sources.put("d", 1);
		sources.put("e", 3);
		sources.put("f", 7);
		sources.put("g", 7);
		sources.put("h", 3);

		for (Entry<String, Integer> entry : sources.entrySet()) {
			ArrayList<String> arr = results.get(entry.getValue());

			if (arr == null) {
				arr = new ArrayList<String>();

				arr.add(entry.getKey());

				results.put(entry.getValue(), arr);
			} else {
				arr.add(entry.getKey());
			}
		}

		for (Entry<Integer, ArrayList<String>> entry : results.entrySet()) {
			System.out.println("key: " + entry.getKey());

			System.out.print("values: ");
			for (String s : entry.getValue()) {
				System.out.print(s + ", ");
			}
			System.out.println();
		}