[template public incCounter(ctx : OclAny, str : String)][invoke('...service.CommonService', 'incCounter(java.lang.Object, java.lang.String)', Sequence{ctx, str})/][/template]

[template public getCounter(ctx : OclAny, str : String)][invoke('...service.CommonService', 'getCounter(java.lang.Object, java.lang.String)', Sequence{ctx, str})/][/template]

public class CommonService {

    public int incCounter(Object context, String str) {
        return Counter.getInstance().incCounter(context, str);
    }

    public int getCounter(Object context, String str) {
        return Counter.getInstance().getCounter(context, str);
    }

}

public class Counter {

    private static volatile Counter instance;

    private Map<Object, Map<String, Integer>> contexts = new HashMap<Object, Map<String, Integer>>();

    private Counter() {
    }

    public static Counter getInstance() {
        if (instance == null) {
            synchronized(Counter.class){
                if (instance == null) {
                    instance = new Counter();
                }
            }
        }
        return instance;
    }

    private Map<String, Integer> getCounters(Object context) {
        if (contexts.containsKey(context)) {
            return contexts.get(context);
        }
        final Map<String, Integer> counters = new HashMap<String, Integer>();
        contexts.put(context, counters);
        return counters;
    }

    public int incCounter(Object context, String str) {
        final Map<String, Integer> counters = getCounters(context);
        if (counters.containsKey(str)) {
            int counter = counters.get(str) + 1;
            counters.put(str, counter);
            return counter;
        }
        counters.put(str, 1);
        return 1;
    }

    public int getCounter(Object context, String str) {
        final Map<String, Integer> counters = getCounters(context);
        if (counters.containsKey(str)) {
            return counters.get(str);
        }
        return 0;
    }

}