Most occasions in logic where it is necessary to keep a counter, a simple integer value is sufficient.
int i=0;
while (...) {
...
++i;
...
}There are some cases where this is not sufficient because an object must be used. For cases like this, we created Counter. The primary operations of Counter are increment/decrement.
The above logic can be equivalently replaced with
Counter i = new Counter();
while (...) {
...
i.increment;
...
}More usefully, it can be used in a context where an object is required.
Map<String,Counter> map;
...
map.get("key1").increment();