package alg;/** * @author zha 字符串之间的转化 */public class Alg3StringToint {    /**     * @param args     */    public static void main(String[] args) {        String intv = "1232192373290";//        int value = http://www.mamicode.com/Integer.parseInt(intv);>//        System.out.println(value);    }    // JDK的源码还是比较好的研究对象    public static int parseInt(String s, int radix)            throws NumberFormatException {        /*         * WARNING: This method may be invoked early during VM initialization         * before IntegerCache is initialized. Care must be taken to not use the         * valueOf method.         */        if (s == null) {            throw new NumberFormatException("null");        }        if (radix < Character.MIN_RADIX) {            throw new NumberFormatException("radix " + radix                    + " less than Character.MIN_RADIX");        }        if (radix > Character.MAX_RADIX) {            throw new NumberFormatException("radix " + radix                    + " greater than Character.MAX_RADIX");        }        int result = 0;        boolean negative = false;        int i = 0, len = s.length();        int limit = -Integer.MAX_VALUE;        int multmin;        int digit;        if (len > 0) {            char firstChar = s.charAt(0);            if (firstChar < ‘0‘) { // Possible leading "+" or "-"                if (firstChar == ‘-‘) {                    negative = true;                    limit = Integer.MIN_VALUE;                } else if (firstChar != ‘+‘)                    throw new NumberFormatException(s);                if (len == 1) // Cannot have lone "+" or "-"                    throw new NumberFormatException(s);                i++;            }            multmin = limit / radix;            while (i < len) {                // Accumulating negatively avoids surprises near MAX_VALUE                digit = Character.digit(s.charAt(i++), radix);                if (digit < 0) {                    throw new NumberFormatException(s);                }                if (result < multmin) {                    throw new NumberFormatException(s);                }                result *= radix;                if (result < limit + digit) {                    throw new NumberFormatException(s);                }                result -= digit;            }        } else {            throw new NumberFormatException(s);        }        return negative ? result : -result;    }}