Java 数字相关操作通用类 NumberUtils.java

package com.*.*.*.utils;import java.math.BigDecimal;
import java.math.BigInteger;
import java.math.RoundingMode;
import java.text.DecimalFormat;
import java.util.regex.Matcher;
import java.util.regex.Pattern;public class NumberUtils
{/**可重复使用的Long常量0L*/public static final Long LONG_ZERO = Long.valueOf(0L);/**可重复使用的Long常量1L*/public static final Long LONG_ONE = Long.valueOf(1L);/**可重复使用的Long常量-1L*/public static final Long LONG_MINUS_ONE = Long.valueOf(-1L);/**可重复使用的Integer常量0*/public static final Integer INTEGER_ZERO = Integer.valueOf(0);/**可重复使用的Integer常量1*/public static final Integer INTEGER_ONE = Integer.valueOf(1);/**可重复使用的Integer常量-1*/public static final Integer INTEGER_MINUS_ONE = Integer.valueOf(-1);/**可重复使用的Short常量0*/public static final Short SHORT_ZERO = Short.valueOf((short) 0);/**可重复使用的Short常量1*/public static final Short SHORT_ONE = Short.valueOf((short) 1);/**可重复使用的Short常量-1*/public static final Short SHORT_MINUS_ONE = Short.valueOf((short) -1);/**可重复使用的Byte常量0*/public static final Byte BYTE_ZERO = Byte.valueOf((byte) 0);/**可重复使用的Byte常量1*/public static final Byte BYTE_ONE = Byte.valueOf((byte) 1);/**可重复使用的Byte常量-1*/public static final Byte BYTE_MINUS_ONE = Byte.valueOf((byte) -1);/**可重复使用的Double常量0.0d*/public static final Double DOUBLE_ZERO = Double.valueOf(0.0d);/**可重复使用的Double常量1.0d*/public static final Double DOUBLE_ONE = Double.valueOf(1.0d);/**可重复使用的Double常量-1.0d*/public static final Double DOUBLE_MINUS_ONE = Double.valueOf(-1.0d);/**可重复使用的Float常量0.0f*/public static final Float FLOAT_ZERO = Float.valueOf(0.0f);/**可重复使用的Float常量1.0f*/public static final Float FLOAT_ONE = Float.valueOf(1.0f);/**可重复使用的Float常量-1.0f*/public static final Float FLOAT_MINUS_ONE = Float.valueOf(-1.0f);/**我们使用的时候无需创建该工具类，像这样使用 NumberUtils.toInt("6");该构造方法是为了符合JavaBean的规范*/public NumberUtils() {super();}//-----------------------------------------------------------------------/**@param str@param pattern "###,###0.0##"@returneg:NumberUtils.formatNumber("2.367","000.00000000")return:002.36700000*/public static String formatNumber(final String str,String pattern) {return new DecimalFormat(pattern).format(toDouble(str));}public static String formatNumber(final Number number,String pattern) {return new DecimalFormat(pattern).format(toDouble(String.valueOf(number)));}/**转换str为int,如果转换失败则返回0*/public static int toInt(final String str) {return toInt(str, 0);}/**转换str为int，如果转换失败则返回defaultValue*/public static int toInt(final String str, final int defaultValue) {return toInt(str,defaultValue,RoundingMode.HALF_UP);}/*RoundingMode.CEILING：取右边最近的整数RoundingMode.DOWN：去掉小数部分取整，也就是正数取左边，负数取右边，相当于向原点靠近的方向取整RoundingMode.FLOOR：取左边最近的正数RoundingMode.HALF_DOWN:五舍六入，负数先取绝对值再五舍六入再负数RoundingMode.HALF_UP:四舍五入，负数原理同上RoundingMode.HALF_EVEN:这个比较绕，整数位若是奇数则四舍五入，若是偶数则五舍六入*/public static int toInt(final String str, RoundingMode roundingMode) {return toInt(str,0,roundingMode);}public static int toInt(final String str, final int defaultValue,RoundingMode roundingMode) {if (str == null){return defaultValue;}try{//return Integer.parseInt(str);BigDecimal bd = new BigDecimal(toDouble(str)).setScale(0, roundingMode);return bd.intValue();} catch (final NumberFormatException nfe){return defaultValue;}}/**转换str为long，如果转换失败则返回0L*/public static long toLong(final String str) {return toLong(str, 0L);}/**转换str为long，如果转换失败则返回defaultValue*/public static long toLong(final String str, final long defaultValue) {if (str == null){return defaultValue;}try{return Long.parseLong(str);} catch (final NumberFormatException nfe){return defaultValue;}}/**转换str为float，如果转换失败则返回0.0f*/public static float toFloat(final String str) {return toFloat(str, 0.0f);}/**转换str为float，如果转换失败则返回defaultValue*/public static float toFloat(final String str, final float defaultValue) {if (str == null){return defaultValue;}try{return Float.parseFloat(str);} catch (final NumberFormatException nfe){return defaultValue;}}/**转换str为double，如果转换失败则返回0.0d*/public static double toDouble(final String str) {return toDouble(str, 0.0d);}/*BigDecimal.ROUND_DOWN 表示不进位BigDecimal.ROUND_UP表示进位*/public static double toDouble(final String str, int digits, RoundingMode roundingMode) {double d = toDouble(str);BigDecimal b = new BigDecimal(d);return b.setScale(digits, roundingMode).doubleValue();}/**转换str为double，如果转换失败则返回defaultValue*/public static double toDouble(final String str, final double defaultValue) {if (str == null){return defaultValue;}try{return Double.parseDouble(str);} catch (final NumberFormatException nfe){return defaultValue;}}/**转换str为byte，如果转换失败则返回0*/public static byte toByte(final String str) {return toByte(str, (byte) 0);}/**转换str为byte，如果转换失败则返回defaultValue*/public static byte toByte(final String str, final byte defaultValue) {if (str == null){return defaultValue;}try{return Byte.parseByte(str);} catch (final NumberFormatException nfe){return defaultValue;}}/**转换str为short，如果转换失败则返回0*/public static short toShort(final String str) {return toShort(str, (short) 0);}/**转换str为short，如果转换失败则返回defaultValue*/public static short toShort(final String str, final short defaultValue) {if (str == null){return defaultValue;}try{return Short.parseShort(str);} catch (final NumberFormatException nfe){return defaultValue;}}/**将一个String的值转换为java.lang.Number如果这个字符串以0x、0X、-0x、-0X、#、-#开始，这个字符将转换成 hexadecimal Integer类型，如果前缀后面的数字超过8个则转换成Long类型如果超过16个则转换成BIgInteger。还会检查这个值是否是以预定义的字符结束，例如'f','F','d','D','l','L'.如果找到对应的，将开始依次创建较大的类型直到找到能匹配这个值的类型。如果没有找到类型标识符，将作为小数进行验证并且是依次从Intger到BigInteger，Float 到BigDecimal。0开头的数字将作为八进制转换，返回的数字是相应的Integer，Long 或BigDecimal如果参数为空则返回null这个方法不会对参数进行trim操作，如果头部或尾部有空格的话将会生成NumberFormatExceptions*/public static Number createNumber(final String str) throws NumberFormatException {if (str == null){return null;}if (Utils.isEmpty(str)){throw new NumberFormatException("A blank string is not a valid number");}// Need to deal with all possible hex prefixes herefinal String[] hex_prefixes = {"0x", "0X", "-0x", "-0X", "#", "-#"};int pfxLen = 0;for (final String pfx : hex_prefixes){if (str.startsWith(pfx)){pfxLen += pfx.length();break;}}if (pfxLen > 0){ // 是十六进制 we have a hex numberchar firstSigDigit = 0; // 去掉开头的0 strip leading zeroesfor (int i = pfxLen; i < str.length(); i++){firstSigDigit = str.charAt(i);if (firstSigDigit == '0'){ // 统计有多少个0开头 count leading zeroespfxLen++;}else{break;}}final int hexDigits = str.length() - pfxLen; //计算不包含0的数字的长度if (hexDigits > 16 || hexDigits == 16 && firstSigDigit > '7'){ // 使用BigIntegerreturn createBigInteger(str);}if (hexDigits > 8 || hexDigits == 8 && firstSigDigit > '7'){ // 使用Longreturn createLong(str);}return createInteger(str);}final char lastChar = str.charAt(str.length() - 1); //获取最后一个数字String mant;String dec;String exp;final int decPos = str.indexOf('.');final int expPos = str.indexOf('e') + str.indexOf('E') + 1; // assumes both not present// if both e and E are present, this is caught by the checks on expPos (which prevent IOOBE)// and the parsing which will detect if e or E appear in a number due to using the wrong offsetif (decPos > -1){ // 这个是一个小数数字 there is a decimal pointif (expPos > -1){ // 这是一个指数 there is an exponentif (expPos < decPos || expPos > str.length()){ // 防止双指数导致IOOBE prevents double exponent causing IOOBEthrow new NumberFormatException(str + " is not a valid number.");}dec = str.substring(decPos + 1, expPos);}else{dec = str.substring(decPos + 1);}mant = getMantissa(str, decPos);}else{if (expPos > -1){if (expPos > str.length()){ // 防止双指数导致IOOBE prevents double exponent causing IOOBEthrow new NumberFormatException(str + " is not a valid number.");}mant = getMantissa(str, expPos);}else{mant = getMantissa(str);}dec = null;}if (!Character.isDigit(lastChar) && lastChar != '.'){if (expPos > -1 && expPos < str.length() - 1){exp = str.substring(expPos + 1, str.length() - 1);}else{exp = null;}//Requesting a specific type.. 是否是特定的类型final String numeric = str.substring(0, str.length() - 1);final boolean allZeros = isAllZeros(mant) && isAllZeros(exp);switch (lastChar){case 'l':case 'L':if (dec == null && exp == null && (numeric.charAt(0) == '-' && isDigits(numeric.substring(1)) || isDigits(numeric))){try{return createLong(numeric);} catch (final NumberFormatException nfe){ // NOPMD// Too big for a long}return createBigInteger(numeric);}throw new NumberFormatException(str + " is not a valid number.");case 'f':case 'F':try{final Float f = NumberUtils.createFloat(str);if (!(f.isInfinite() || f.floatValue() == 0.0F && !allZeros)){//If it's too big for a float or the float value = 0 and the string//has non-zeros in it, then float does not have the precision we wantreturn f;}} catch (final NumberFormatException nfe){ // NOPMD// ignore the bad number}//$FALL-THROUGH$case 'd':case 'D':try{final Double d = NumberUtils.createDouble(str);if (!(d.isInfinite() || d.floatValue() == 0.0D && !allZeros)){return d;}} catch (final NumberFormatException nfe){ // NOPMD// ignore the bad number}try{return createBigDecimal(numeric);} catch (final NumberFormatException e){ // NOPMD// ignore the bad number}//$FALL-THROUGH$default:throw new NumberFormatException(str + " is not a valid number.");}}//User doesn't have a preference on the return type, so let's start//small and go from there...//不属于任何类型if (expPos > -1 && expPos < str.length() - 1){exp = str.substring(expPos + 1, str.length());}else{exp = null;}if (dec == null && exp == null){ // no decimal point and no exponent//Must be an Integer, Long, Bigintegertry{return createInteger(str);} catch (final NumberFormatException nfe){ // NOPMD// ignore the bad number}try{return createLong(str);} catch (final NumberFormatException nfe){ // NOPMD// ignore the bad number}return createBigInteger(str);}//Must be a Float, Double, BigDecimal//也许是Float，Double，BigDecimalfinal boolean allZeros = isAllZeros(mant) && isAllZeros(exp);try{final Float f = createFloat(str);final Double d = createDouble(str);if (!f.isInfinite() && !(f.floatValue() == 0.0F && !allZeros) && f.toString().equals(d.toString())){return f;}if (!d.isInfinite() && !(d.doubleValue() == 0.0D && !allZeros)){final BigDecimal b = createBigDecimal(str);if (b.compareTo(BigDecimal.valueOf(d.doubleValue())) == 0){return d;}return b;}} catch (final NumberFormatException nfe){ // NOPMD// ignore the bad number}return createBigDecimal(str);}/**createNumber()方法使用获取尾数的，也就是返回不包括符号位的数字*/private static String getMantissa(final String str) {return getMantissa(str, str.length());}/**createNumber()方法使用获取尾数的，也就是返回不包括符号位的数字可以指定获取长度*/private static String getMantissa(final String str, final int stopPos) {final char firstChar = str.charAt(0);final boolean hasSign = firstChar == '-' || firstChar == '+';return hasSign ? str.substring(1, stopPos) : str.substring(0, stopPos);}/**createNumber()方法使用如果字符串为空返回true，如果字符串中的没有等于0的返回true*/private static boolean isAllZeros(final String str) {if (str == null){return true;}for (int i = str.length() - 1; i >= 0; i--){if (str.charAt(i) != '0'){return false;}}return str.length() > 0;}//-----------------------------------------------------------------------/**转换String为Float如果String为空则返回null*/public static Float createFloat(final String str) {if (str == null){return null;}return Float.valueOf(str);}/**转换String为Double如果String为空则返回null*/public static Double createDouble(final String str) {if (str == null){return null;}return Double.valueOf(str);}/**转换String为Integer，处理hex和octal进制。注意0开头表示octal进制，不会进行trim操作*/public static Integer createInteger(final String str) {if (str == null){return null;}// decode() handles 0xAABD and 0777 (hex and octal) as well.return Integer.decode(str);}/**转换String为Long，处理hex和octal进制。注意0开头表示octal进制，不会进行trim操作*/public static Long createLong(final String str) {if (str == null){return null;}return Long.decode(str);}/**转换String为BigInteger从3.2版本后可以处理hex(0x or #开头)和octal (0开头)进制字符串为null返回null*/public static BigInteger createBigInteger(final String str) {if (str == null){return null;}int pos = 0; // offset within stringint radix = 10;boolean negate = false; // need to negate later?if (str.startsWith("-")){negate = true;pos = 1;}if (str.startsWith("0x", pos) || str.startsWith("0X", pos)){ // hexradix = 16;pos += 2;}else if (str.startsWith("#", pos)){ // alternative hex (allowed by Long/Integer)radix = 16;pos++;}else if (str.startsWith("0", pos) && str.length() > pos + 1){ // octal; so long as there are additional digitsradix = 8;pos++;} // default is to treat as decimalfinal BigInteger value = new BigInteger(str.substring(pos), radix);return negate ? value.negate() : value;}/**转换String为Double如果String为空则返回null*/public static BigDecimal createBigDecimal(final String str) {if (str == null){return null;}// handle JDK1.3.1 bug where "" throws IndexOutOfBoundsExceptionif (Utils.isEmpty(str)){throw new NumberFormatException("A blank string is not a valid number");}if (str.trim().startsWith("--")){// this is protection for poorness in java.lang.BigDecimal.// it accepts this as a legal value, but it does not appear// to be in specification of class. OS X Java parses it to// a wrong value.throw new NumberFormatException(str + " is not a valid number.");}return new BigDecimal(str);}// Min in array//--------------------------------------------------------------------/**返回数组的最小值*/public static long min(final long... array) {// Validates inputvalidateArray(array);// Finds and returns minlong min = array[0];for (int i = 1; i < array.length; i++){if (array[i] < min){min = array[i];}}return min;}/**返回数组中最小的从3.4版本后 修改方法签名  min(int[]) to min(int...)*/public static int min(final int... array) {// Validates inputvalidateArray(array);// Finds and returns minint min = array[0];for (int j = 1; j < array.length; j++){if (array[j] < min){min = array[j];}}return min;}/**返回数组中最小的从3.4版本后 修改方法签名  min(short[]) to min(short...)*/public static short min(final short... array) {// Validates inputvalidateArray(array);// Finds and returns minshort min = array[0];for (int i = 1; i < array.length; i++){if (array[i] < min){min = array[i];}}return min;}/**返回数组中最小的从3.4版本后 修改方法签名  min(byte[]) to min(byte...)*/public static byte min(final byte... array) {// Validates inputvalidateArray(array);// Finds and returns minbyte min = array[0];for (int i = 1; i < array.length; i++){if (array[i] < min){min = array[i];}}return min;}/**返回数组中最小的从3.4版本后 修改方法签名  min(double[]) to min(double...)*/public static double min(final double... array) {// Validates inputvalidateArray(array);// Finds and returns mindouble min = array[0];for (int i = 1; i < array.length; i++){if (Double.isNaN(array[i])){return Double.NaN;}if (array[i] < min){min = array[i];}}return min;}/**返回数组中最小的从3.4版本后 修改方法签名  min(float[]) to min(float...)*/public static float min(final float... array) {// Validates inputvalidateArray(array);// Finds and returns minfloat min = array[0];for (int i = 1; i < array.length; i++){if (Float.isNaN(array[i])){return Float.NaN;}if (array[i] < min){min = array[i];}}return min;}// Max in array//--------------------------------------------------------------------/**返回数组中最大的从3.4版本后 修改方法签名  min(long[]) to min(long...)*/public static long max(final long... array) {// Validates inputvalidateArray(array);// Finds and returns maxlong max = array[0];for (int j = 1; j < array.length; j++){if (array[j] > max){max = array[j];}}return max;}/**返回数组中最大的从3.4版本后 修改方法签名  min(int[]) to min(int...)*/public static int max(final int... array) {// Validates inputvalidateArray(array);// Finds and returns maxint max = array[0];for (int j = 1; j < array.length; j++){if (array[j] > max){max = array[j];}}return max;}/**返回数组中最大的从3.4版本后 修改方法签名  min(short[]) to min(short...)*/public static short max(final short... array) {// Validates inputvalidateArray(array);// Finds and returns maxshort max = array[0];for (int i = 1; i < array.length; i++){if (array[i] > max){max = array[i];}}return max;}/**返回数组中最大的从3.4版本后 修改方法签名  min(byte[]) to min(byte...)*/public static byte max(final byte... array) {// Validates inputvalidateArray(array);// Finds and returns maxbyte max = array[0];for (int i = 1; i < array.length; i++){if (array[i] > max){max = array[i];}}return max;}/**返回数组中最大的从3.4版本后 修改方法签名  min(double[]) to min(double...)*/public static double max(final double... array) {// Validates inputvalidateArray(array);// Finds and returns maxdouble max = array[0];for (int j = 1; j < array.length; j++){if (Double.isNaN(array[j])){return Double.NaN;}if (array[j] > max){max = array[j];}}return max;}/**返回数组中最大的从3.4版本后 修改方法签名  min(float[]) to min(float...)*/public static float max(final float... array) {// Validates inputvalidateArray(array);// Finds and returns maxfloat max = array[0];for (int j = 1; j < array.length; j++){if (Float.isNaN(array[j])){return Float.NaN;}if (array[j] > max){max = array[j];}}return max;}/**校验参数数组是不是nulll或empty*/private static void validateArray(final Object array) {/* Validate.isTrue(array != null, "The Array must not be null");Validate.isTrue(Array.getLength(array) != 0, "Array cannot be empty.");*/}// 3 param min//-----------------------------------------------------------------------/**获取三个long类型参数中最小的*/public static long min(long a, final long b, final long c) {if (b < a){a = b;}if (c < a){a = c;}return a;}/**获取三个int类型参数中最小的*/public static int min(int a, final int b, final int c) {if (b < a){a = b;}if (c < a){a = c;}return a;}/**获取三个short类型参数中最小的*/public static short min(short a, final short b, final short c) {if (b < a){a = b;}if (c < a){a = c;}return a;}/**获取三个byte类型参数中最小的*/public static byte min(byte a, final byte b, final byte c) {if (b < a){a = b;}if (c < a){a = c;}return a;}/**获取三个double类型参数中最小的*/public static double min(final double a, final double b, final double c) {return Math.min(Math.min(a, b), c);}/**获取三个float类型参数中最小的如果有一个值是NaN，则NaN将返回，当做无尽处理*/public static float min(final float a, final float b, final float c) {return Math.min(Math.min(a, b), c);}// 3 param max//-----------------------------------------------------------------------/**获取三个long类型参数中最大的*/public static long max(long a, final long b, final long c) {if (b > a){a = b;}if (c > a){a = c;}return a;}/**获取三个int类型参数中最大的*/public static int max(int a, final int b, final int c) {if (b > a){a = b;}if (c > a){a = c;}return a;}/**获取三个short类型参数中最大的*/public static short max(short a, final short b, final short c) {if (b > a){a = b;}if (c > a){a = c;}return a;}/**获取三个byte类型参数中最大的*/public static byte max(byte a, final byte b, final byte c) {if (b > a){a = b;}if (c > a){a = c;}return a;}/**获取三个double类型参数中最大的*/public static double max(final double a, final double b, final double c) {return Math.max(Math.max(a, b), c);}/**获取三个float类型参数中最大的*/public static float max(final float a, final float b, final float c) {return Math.max(Math.max(a, b), c);}//-----------------------------------------------------------------------public static boolean isNumeric(String str) {Pattern pattern = Pattern.compile("[0-9]*");Matcher isNum = pattern.matcher(str);return isNum.matches();}/**判断字符串仅仅包含数字字符null或empty返回false*/public static boolean isDigits(final String str) {return isNumeric(str);}/**过时的方法被isCreatable取代*/@Deprecatedpublic static boolean isNumber(final String str) {return isCreatable(str);}/**校验String是否是一个有效的Java number校验number包含hexadecimal 的标记 0x or 0X、八进制数字、科学计数法和其他的数字标记类型，比如1234L以0开头的非十六进制的数统一作为八进制的数处理。所以String为09将返回false，因为9不是一个有效的八进制。但是是以0.开头的数字，都作为十进制处理null或empty或blank字符串返回false*/public static boolean isCreatable(final String str) {if (Utils.isEmpty(str)){return false;}final char[] chars = str.toCharArray();int sz = chars.length;boolean hasExp = false;boolean hasDecPoint = false;boolean allowSigns = false;boolean foundDigit = false;// deal with any possible sign up frontfinal int start = chars[0] == '-' || chars[0] == '+' ? 1 : 0;final boolean hasLeadingPlusSign = start == 1 && chars[0] == '+';if (sz > start + 1 && chars[start] == '0'){ // leading 0if (chars[start + 1] == 'x' || chars[start + 1] == 'X'){ // leading 0x/0Xint i = start + 2;if (i == sz){return false; // str == "0x"}// checking hex (it can't be anything else)for (; i < chars.length; i++){if ((chars[i] < '0' || chars[i] > '9') && (chars[i] < 'a' || chars[i] > 'f') && (chars[i] < 'A' || chars[i] > 'F')){return false;}}return true;}else if (Character.isDigit(chars[start + 1])){// leading 0, but not hex, must be octalint i = start + 1;for (; i < chars.length; i++){if (chars[i] < '0' || chars[i] > '7'){return false;}}return true;}}sz--; // don't want to loop to the last char, check it afterwords// for type qualifiersint i = start;// loop to the next to last char or to the last char if we need another digit to// make a valid number (e.g. chars[0..5] = "1234E")while (i < sz || i < sz + 1 && allowSigns && !foundDigit){if (chars[i] >= '0' && chars[i] <= '9'){foundDigit = true;allowSigns = false;}else if (chars[i] == '.'){if (hasDecPoint || hasExp){// two decimal points or dec in exponentreturn false;}hasDecPoint = true;}else if (chars[i] == 'e' || chars[i] == 'E'){// we've already taken care of hex.if (hasExp){// two E'sreturn false;}if (!foundDigit){return false;}hasExp = true;allowSigns = true;}else if (chars[i] == '+' || chars[i] == '-'){if (!allowSigns){return false;}allowSigns = false;foundDigit = false; // we need a digit after the E}else{return false;}i++;}if (i < chars.length){if (chars[i] >= '0' && chars[i] <= '9'){return !hasLeadingPlusSign || hasDecPoint;}if (chars[i] == 'e' || chars[i] == 'E'){// can't have an E at the last bytereturn false;}if (chars[i] == '.'){if (hasDecPoint || hasExp){// two decimal points or dec in exponentreturn false;}// single trailing decimal point after non-exponent is okreturn foundDigit;}if (!allowSigns && (chars[i] == 'd' || chars[i] == 'D' || chars[i] == 'f' || chars[i] == 'F')){return foundDigit;}if (chars[i] == 'l' || chars[i] == 'L'){// not allowing L with an exponent or decimal pointreturn foundDigit && !hasExp && !hasDecPoint;}// last character is illegalreturn false;}// allowSigns is true iff the val ends in 'E'// found digit it to make sure weird stuff like '.' and '1E-' doesn't passreturn !allowSigns && foundDigit;}/**校验提供的字符串是否可以解析为number可解析的number包括下面方法可以执行字符串 Integer.parseInt(String), Long.parseLong(String), Float.parseFloat(String) or Double.parseDouble(String).这个方法可以替代java.text.ParseException异常十六进制和科学计数符号认为是不可解析的@since 3.4*/public static boolean isParsable(final String str) {if (Utils.isEmpty(str)){return false;}if (str.charAt(str.length() - 1) == '.'){return false;}if (str.charAt(0) == '-'){if (str.length() == 1){return false;}return withDecimalsParsing(str, 1);}return withDecimalsParsing(str, 0);}private static boolean withDecimalsParsing(final String str, final int beginIdx) {int decimalPoints = 0;for (int i = beginIdx; i < str.length(); i++){final boolean isDecimalPoint = str.charAt(i) == '.';if (isDecimalPoint){decimalPoints++;}if (decimalPoints > 1){return false;}if (!isDecimalPoint && !Character.isDigit(str.charAt(i))){return false;}}return true;}/**比例两个int的大小，在Java7有提供相同的方法@since 3.4*/public static int compare(final int x, final int y) {if (x == y){return 0;}return x < y ? -1 : 1;}/**比例两个long的大小，在Java7有提供相同的方法@since 3.4*/public static int compare(final long x, final long y) {if (x == y){return 0;}return x < y ? -1 : 1;}/**比例两个long的大小，在Java7有提供相同的方法@since 3.4*/public static int compare(final short x, final short y) {if (x == y){return 0;}return x < y ? -1 : 1;}/**比例两个byte的大小，在Java7有提供相同的方法*/public static int compare(final byte x, final byte y) {return x - y;}}

个别用法：

NumberUtils.toInt("2.36")   //默认四舍五入 返回  2

NumberUtils.toInt("2.36", RoundingMode.UP) //向上取整 返回3

NumberUtils.formatNumber("2.36","0.0") // 返回 2.4

NumberUtils.formatNumber("2.36","0000.0000") // 返回 0002.3600

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