java - How to sum values in a Map with a stream?

Question

I want the equivalent of this with a stream:

public static <T extends Number> T getSum(final Map<String, T> data) {
    T sum = 0;
    for (String key: data.keySet())
        sum += data.get(key);
    return sum;
}

This code doesn't actually compile because 0 cannot be assigned to type T, but you get the idea.

Answer 1

You can do this:

int sum = data.values().stream().mapToInt(Integer::parseInt).sum();