gistfile1.java

final Map<String, String> resultMap = new HashMap<String, String>();

for (String val: "dave:123, john:314,, matt:989".split(",")) {
    if (val != null && ! "".equals(val.trim())) {
        final String[] keyValue = val.split(":");

        resultMap.put(keyValue[0].trim(), keyValue[1].trim());
    }
}

// resultMap: {dave=123, john=314, matt=989}