为什么AbstractStringBuilder.append的行为与MIN_VALUE不同？

Question

Consider the following methods in java.lang.AbstractStringBuilder

---

Long

public AbstractStringBuilder append(long l) {
    if (l == Long.MIN_VALUE) {
        append("-9223372036854775808");
        return this;
    }
    int appendedLength = (l < 0) ? Long.stringSize(-l) + 1
                                 : Long.stringSize(l);
    int spaceNeeded = count + appendedLength;
    ensureCapacityInternal(spaceNeeded);
    Long.getChars(l, spaceNeeded, value);
    count = spaceNeeded;
    return this;
}

Integer

public AbstractStringBuilder append(int i) {
    if (i == Integer.MIN_VALUE) {
        append("-2147483648");
        return this;
    }
    int appendedLength = (i < 0) ? Integer.stringSize(-i) + 1
                                 : Integer.stringSize(i);
    int spaceNeeded = count + appendedLength;
    ensureCapacityInternal(spaceNeeded);
    Integer.getChars(i, spaceNeeded, value);
    count = spaceNeeded;
    return this;
}

---

Why does AbstractStringBuilder#append use a different algorithm to append the MIN_VALUE ?

Answer 1

因为stringSize算法根据其输入的绝对值估计所需的字符数，除了MIN_VALUE没有可表示的绝对值： -Integer.MIN_VALUE == Integer.MIN_VALUE 。

Answer 2

Because Integer.stringSize requires a non-negative argument. The code looks like this:

final static int [] sizeTable = { 9, 99, 999, 9999, 99999, 999999, 9999999,
                                  99999999, 999999999, Integer.MAX_VALUE };

// Requires positive x
static int stringSize(int x) {
    for (int i=0; ; i++)
        if (x <= sizeTable[i])
            return i+1;
}