1. 區(qū)別

toString方法將數(shù)字轉(zhuǎn)為有符號(hào)數(shù)對(duì)應(yīng)的字符串塑崖，toUnsignedString是將數(shù)字轉(zhuǎn)為有符號(hào)數(shù)對(duì)應(yīng)的字符串。

2. toString(long i, int radix)

public static String toString(long i, int radix) {
        if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
            radix = 10;
        if (radix == 10)
            return toString(i);
        char[] buf = new char[65];
        int charPos = 64;
        boolean negative = (i < 0);

        if (!negative) {
            i = -i;
        }

        while (i <= -radix) {
            buf[charPos--] = Integer.digits[(int)(-(i % radix))];
            i = i / radix;
        }
        buf[charPos] = Integer.digits[(int)(-i)];

        if (negative) {
            buf[--charPos] = '-';
        }

        return new String(buf, charPos, (65 - charPos));
    }

• 當(dāng)要轉(zhuǎn)為十進(jìn)制的時(shí)候燕侠，直接用toString方法,toString里面主要是用了getChars方法，我們?cè)谥?a target="_blank" rel="nofollow">http://www.chenchen.zone/articles/2018/09/27/1538041030708.html講過(guò)。

    public static String toString(long i) {
        if (i == Long.MIN_VALUE)
            return "-9223372036854775808";
        int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
        char[] buf = new char[size];
        getChars(i, size, buf);
        return new String(buf, true);
    }

• 當(dāng)非10進(jìn)制的時(shí)候

boolean negative = (i < 0);
if (!negative) {
            i = -i;
        }

        while (i <= -radix) {
            buf[charPos--] = Integer.digits[(int)(-(i % radix))];
            i = i / radix;
        }
        buf[charPos] = Integer.digits[(int)(-i)];

        if (negative) {
            buf[--charPos] = '-';
        }

這里有個(gè)比較巧妙的地方我開(kāi)始沒(méi)有想通诊杆，就是為什么把數(shù)字都統(tǒng)一轉(zhuǎn)為負(fù)數(shù)來(lái)處理呢捉腥。首先肯定是統(tǒng)一轉(zhuǎn)為正數(shù)或者負(fù)數(shù)處理氓拼，那為什么是負(fù)數(shù)。答案就是有負(fù)數(shù)數(shù)字負(fù)數(shù)比負(fù)數(shù)多一個(gè)數(shù)字抵碟，比如64位系統(tǒng)Long的范圍是-9223372036854775808 ~ 9223372036854775807桃漾。當(dāng)遇到Long最大正數(shù)9223372036854775807時(shí)，可以轉(zhuǎn)為-9223372036854775807拟逮，但是當(dāng)你遇到Long最小負(fù)數(shù)-9223372036854775808時(shí)轉(zhuǎn)為正數(shù)就會(huì)溢出呈队。所以統(tǒng)一轉(zhuǎn)為負(fù)數(shù)處理可以多處理一個(gè)數(shù)。

3. toUnsignedString(long i, int radix)

    public static String toUnsignedString(long i, int radix) {
        if (i >= 0)
            return toString(i, radix);
        else {
            switch (radix) {
            case 2:
                return toBinaryString(i);

            case 4:
                return toUnsignedString0(i, 2);

            case 8:
                return toOctalString(i);

            case 10:
                /*
                 * We can get the effect of an unsigned division by 10
                 * on a long value by first shifting right, yielding a
                 * positive value, and then dividing by 5.  This
                 * allows the last digit and preceding digits to be
                 * isolated more quickly than by an initial conversion
                 * to BigInteger.
                 */
                long quot = (i >>> 1) / 5;
                long rem = i - quot * 10;
                return toString(quot) + rem;

            case 16:
                return toHexString(i);

            case 32:
                return toUnsignedString0(i, 5);

            default:
                return toUnsignedBigInteger(i).toString(radix);
            }
        }
    }

• 正數(shù)toString和toUnsignedString是一樣的
• 負(fù)數(shù)使用toUnsignedString0方法唱歧，這個(gè)我們之前http://www.chenchen.zone/articles/2018/09/25/1537868505126.html講過(guò)

作者 @沒(méi)有故事的老大爺
一定要專注宪摧，這樣才會(huì)忘記痛苦