Is is possible to iterate through only half of the provided hashmap?

I have a Hashmap< String, String> p and I’m trying to replace half of the values of the keys with ‘-‘
For instance, lets say my current Hashmap has the following values

"A", "100"
"B", "400"
"C", "600"
"D", "845"

I want to somehow manipulate only half (first two in this case) of the key of the values by changing their values from the provided integer to a ‘-‘.
So it would look like this:

    "A", "-"
    "B", "-"
    "C", "600"
    "D", "845"

I’ve attempted this, but to no avail.

for (String i : p.keySet()/2) {
  p.replace(i, '-')
}

Is there a way to do this? If yes, can you please explain how?

>Solution :

You should do something like this:

int maxiterations = p.keySet().size() / 2;
Iterator<String> iterator = p.keySet().iterator();
for (int i=0; i < maxiterations; i++) {
    if (iterator.hasNext()) {
        String key = iterator.next();
        p.replace(key, "-");
    }
}

Or

int iterations = p.keySet().size() / 2;
do {
    if (iterator.hasNext()) {
        p.replace(iterator.next(), "-");
    }
} while (--iterations > 0);