Question

It appears in java.lang.String.java, that Java will only generate the hashcode, and then store it, after a call to hashcode(), but why not just make the hashcode in the constructor?

The relevant code:

if (h == 0 && count > 0) {
    int off = offset;
    char val[] = value;
    int len = count;

    for (int i = 0; i < len; i++) {
        h = 31*h + val[off++];
    }

    hash = h;
}

could for the most part be placed in the constructor.

Answer 1

Why spend time generating a hash code that most likely will not be used? Most strings are constructed, used and then garbage collected without the hashcode() ever being called.