如果计算的散列码超过INTEGER MAX LIMIT，会发生什么情况？ [英] What happens if hashcode calculated exceeds the INTEGER MAX LIMIT?

问题描述

以下是Java HashTable Class的hashCode（）实现。如果散列表中元素的数量很大，散列码超过INTEGER MAX LIMIT -2,147,483,648至2,147,483,647，该怎么办？我假设hashCodes是正整数。

Here is the hashCode() implementation from Java HashTable Class. What if the number of elements in the hashtable is huge and the hashcode exceeds the INTEGER MAX LIMIT -2,147,483,648 to 2,147,483,647 ? I assume hashCodes will be positive integers.

 public synchronized int hashCode() {

    int h = 0;
    if (count == 0 || loadFactor < 0)
        return h;  // Returns zero

    loadFactor = -loadFactor;  // Mark hashCode computation in progress
    Entry[] tab = table;
    for (int i = 0; i < tab.length; i++)
        for (Entry e = tab[i]; e != null; e = e.next)
            h += e.key.hashCode() ^ e.value.hashCode();
    loadFactor = -loadFactor;  // Mark hashCode computation complete

    return h;
}

推荐答案

我假设hashCodes是正整数。

I assume hashCodes will be positive integers.

不，不一定。他们只是整数。它们肯定是负面的，在计算散列码时可以有整数溢出。理想的散列码将在整个范围内均匀分布（在这种情况下 int ）。任何使用的哈希代码都必须考虑到值为负值的可能性。

No, not necessarily. They're just integers. They can definitely be negative, and it's fine to have integer overflow while computing a hash code. An ideal hash code will be spread uniformly across the whole of its range (int in this case). Anything using a hash code definitely needs to take into account the possibility of the value being negative.

这篇关于如果计算的散列码超过INTEGER MAX LIMIT，会发生什么情况？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！