Best way to make a counter in java code example

Example: counter in java

HashMap<String, MutableInteger> efficientCounter = new HashMap<String, MutableInteger>();
 
for (String a : sArr) {
	MutableInteger initValue = new MutableInteger(1);
	MutableInteger oldValue = efficientCounter.put(a, initValue);
 
	if(oldValue != null){
		initValue.set(oldValue.get() + 1);
	}
}