java 数字转换为字符串

转换为二进制字符串：

i >>>= 1是将i右移一二进制位，这样就去除了最低一位。i & 1是位的与运算，会得到最低二进制位。

    public static String toBinaryString(int i) {
        int bufLen = 32;  // Max number of binary digits in an int
        char[] buf = new char[bufLen];
        int cursor = bufLen;

        do {
            buf[--cursor] = (char) ((i & 1) + '0');
        }  while ((i >>>= 1) != 0);

        return new String(cursor, bufLen - cursor, buf);
    }

转换为十六进制字符串：

DIGITS[i & 0xF]也可以用forDigit(int digit, int radix)转换为字符。

    static final char[] DIGITS = {
        '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
        'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
        'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',
        'u', 'v', 'w', 'x', 'y', 'z'
    };
    public static String toHexString(int i) {
        int bufLen = 8;  // Max number of hex digits in an int
        char[] buf = new char[bufLen];
        int cursor = bufLen;

        do {
            buf[--cursor] = DIGITS[i & 0xF];
        } while ((i >>>= 4) != 0);

        return new String(cursor, bufLen - cursor, buf);
    }

转换为八进制字符串：

    public static String toOctalString(int i) {
        int bufLen = 11;  // Max number of octal digits in an int
        char[] buf = new char[bufLen];
        int cursor = bufLen;

        do {
            buf[--cursor] = (char) ((i & 7) + '0');
        } while ((i >>>= 3) != 0);

        return new String(cursor, bufLen - cursor, buf);
    }

任意进制转换为字符串：

    public static String toString(int i, int radix) {
        if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX) {
            radix = 10;
        }

        boolean negative = false;
        if (i < 0) {
            negative = true;
        } else {
            i = -i;
        }

        int bufLen = radix < 8 ? 33 : 12;  
        char[] buf = new char[bufLen];
        int cursor = bufLen;

        do {
            int q = i / radix;
            buf[--cursor] = DIGITS[radix * q - i];
            i = q;
        } while (i != 0);

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

        return new String(cursor, bufLen - cursor, buf);
    }