AbstractStringBuilder类中的expandCapacity方法

Question

我正在查看此类的源代码，并从StringBUffer.append();调用的append方法开始

public AbstractStringBuilder append(String str) {
   if (str == null) str = "null";
       int len = str.length();
   if (len == 0) return this;
   int newCount = count + len;
   if (newCount > value.length)
      expandCapacity(newCount); // newcount is the new volumn of a char array
    str.getChars(0, len, value, count);
    count = newCount;
    return this;
  }

然后我深入研究enpandCapacity方法

void expandCapacity(int minimumCapacity) {
    int newCapacity = (value.length + 1) * 2; //here value is a char array 
    if (newCapacity < 0) { // Why is newCapacity less than 0?
                           // Is that possible? When it will be possible?
        newCapacity = Integer.MAX_VALUE;
    } else if (minimumCapacity > newCapacity) {
        newCapacity = minimumCapacity;
    }
    value = Arrays.copyOf(value, newCapacity);
}

为什么newCapacity小于0？那可能吗？什么时候可能？

Answer 1

是;一旦超过int类型的最大值（ 2 ^ 31 - 1 ），有符号整数就会变为负数。如果你看一下，它们基本上限制了Integer.MAX_VALUE的容量。类似问题here。