Mega Code Archive
Turns a string value into a java lang Number
<![CDATA[
import java.math.BigDecimal;
import java.math.BigInteger;
/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* Contains useful helper methods for classes within this package.
*
* @author John Keyes (john at integralsource.com)
* @version $Revision: 680644 $, $Date: 2008-07-29 01:13:48 -0700 (Tue, 29 Jul 2008) $
*/
public class Main {
//--------------------------------------------------------------------
// must handle Long, Float, Integer, Float, Short,
// BigDecimal, BigInteger and Byte
// useful methods:
// Byte.decode(String)
// Byte.valueOf(String,int radix)
// Byte.valueOf(String)
// Double.valueOf(String)
// Float.valueOf(String)
// new Float(String)
// Integer.valueOf(String,int radix)
// Integer.valueOf(String)
// Integer.decode(String)
// Integer.getInteger(String)
// Integer.getInteger(String,int val)
// Integer.getInteger(String,Integer val)
// new Integer(String)
// new Double(String)
// new Byte(String)
// new Long(String)
// Long.getLong(String)
// Long.getLong(String,int)
// Long.getLong(String,Integer)
// Long.valueOf(String,int)
// Long.valueOf(String)
// new Short(String)
// Short.decode(String)
// Short.valueOf(String,int)
// Short.valueOf(String)
// new BigDecimal(String)
// new BigInteger(String)
// new BigInteger(String,int radix)
// Possible inputs:
// 45 45.5 45E7 4.5E7 Hex Oct Binary xxxF xxxD xxxf xxxd
// plus minus everything. Prolly more. A lot are not separable.
/**
* <p>Turns a string value into a java.lang.Number.</p>
*
* <p>First, the value is examined for a type qualifier on the end
* (<code>'f','F','d','D','l','L'</code>). If it is found, it starts
* trying to create successively larger types from the type specified
* until one is found that can hold the value.</p>
*
* <p>If a type specifier is not found, it will check for a decimal point
* and then try successively larger types from <code>Integer</code> to
* <code>BigInteger</code> and from <code>Float</code> to
* <code>BigDecimal</code>.</p>
*
* <p>If the string starts with <code>0x</code> or <code>-0x</code>, it
* will be interpreted as a hexadecimal integer. Values with leading
* <code>0</code>'s will not be interpreted as octal.</p>
*
* @param val String containing a number
* @return Number created from the string
* @throws NumberFormatException if the value cannot be converted
*/
public static Number createNumber(String val) throws NumberFormatException {
if (val == null) {
return null;
}
if (val.length() == 0) {
throw new NumberFormatException("\"\" is not a valid number.");
}
if (val.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.
return null;
}
if (val.startsWith("0x") || val.startsWith("-0x")) {
return createInteger(val);
}
char lastChar = val.charAt(val.length() - 1);
String mant;
String dec;
String exp;
int decPos = val.indexOf('.');
int expPos = val.indexOf('e') + val.indexOf('E') + 1;
if (decPos > -1) {
if (expPos > -1) {
if (expPos < decPos) {
throw new NumberFormatException(val + " is not a valid number.");
}
dec = val.substring(decPos + 1, expPos);
} else {
dec = val.substring(decPos + 1);
}
mant = val.substring(0, decPos);
} else {
if (expPos > -1) {
mant = val.substring(0, expPos);
} else {
mant = val;
}
dec = null;
}
if (!Character.isDigit(lastChar)) {
if (expPos > -1 && expPos < val.length() - 1) {
exp = val.substring(expPos + 1, val.length() - 1);
} else {
exp = null;
}
//Requesting a specific type..
String numeric = val.substring(0, val.length() - 1);
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 (NumberFormatException nfe) {
//Too big for a long
}
return createBigInteger(numeric);
}
throw new NumberFormatException(val + " is not a valid number.");
case 'f' :
case 'F' :
try {
Float f = createFloat(numeric);
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 want
return f;
}
} catch (NumberFormatException e) {
// ignore the bad number
}
//Fall through
case 'd' :
case 'D' :
try {
Double d = createDouble(numeric);
if (!(d.isInfinite() || (d.floatValue() == 0.0D && !allZeros))) {
return d;
}
} catch (NumberFormatException nfe) {
// empty catch
}
try {
return createBigDecimal(numeric);
} catch (NumberFormatException e) {
// empty catch
}
//Fall through
default :
throw new NumberFormatException(val + " is not a valid number.");
}
} else {
//User doesn't have a preference on the return type, so let's start
//small and go from there...
if (expPos > -1 && expPos < val.length() - 1) {
exp = val.substring(expPos + 1, val.length());
} else {
exp = null;
}
if (dec == null && exp == null) {
//Must be an int,long,bigint
try {
return createInteger(val);
} catch (NumberFormatException nfe) {
// empty catch
}
try {
return createLong(val);
} catch (NumberFormatException nfe) {
// empty catch
}
return createBigInteger(val);
} else {
//Must be a float,double,BigDec
boolean allZeros = isAllZeros(mant) && isAllZeros(exp);
try {
Float f = createFloat(val);
if (!(f.isInfinite() || (f.floatValue() == 0.0F && !allZeros))) {
return f;
}
} catch (NumberFormatException nfe) {
// empty catch
}
try {
Double d = createDouble(val);
if (!(d.isInfinite() || (d.doubleValue() == 0.0D && !allZeros))) {
return d;
}
} catch (NumberFormatException nfe) {
// empty catch
}
return createBigDecimal(val);
}
}
}
/**
* <p>Utility method for {@link #createNumber(java.lang.String)}.</p>
*
* <p>Returns <code>true</code> if s is <code>null</code>.</p>
*
* @param s the String to check
* @return if it is all zeros or <code>null</code>
*/
private static boolean isAllZeros(String s) {
if (s == null) {
return true;
}
for (int i = s.length() - 1; i >= 0; i--) {
if (s.charAt(i) != '0') {
return false;
}
}
return s.length() > 0;
}
//--------------------------------------------------------------------
/**
* <p>Convert a <code>String</code> to a <code>Float</code>.</p>
*
* @param val a <code>String</code> to convert
* @return converted <code>Float</code>
* @throws NumberFormatException if the value cannot be converted
*/
public static Float createFloat(String val) {
return Float.valueOf(val);
}
/**
* <p>Convert a <code>String</code> to a <code>Double</code>.</p>
*
* @param val a <code>String</code> to convert
* @return converted <code>Double</code>
* @throws NumberFormatException if the value cannot be converted
*/
public static Double createDouble(String val) {
return Double.valueOf(val);
}
/**
* <p>Convert a <code>String</code> to a <code>Integer</code>, handling
* hex and octal notations.</p>
*
* @param val a <code>String</code> to convert
* @return converted <code>Integer</code>
* @throws NumberFormatException if the value cannot be converted
*/
public static Integer createInteger(String val) {
// decode() handles 0xAABD and 0777 (hex and octal) as well.
return Integer.decode(val);
}
/**
* <p>Convert a <code>String</code> to a <code>Long</code>.</p>
*
* @param val a <code>String</code> to convert
* @return converted <code>Long</code>
* @throws NumberFormatException if the value cannot be converted
*/
public static Long createLong(String val) {
return Long.valueOf(val);
}
/**
* <p>Convert a <code>String</code> to a <code>BigInteger</code>.</p>
*
* @param val a <code>String</code> to convert
* @return converted <code>BigInteger</code>
* @throws NumberFormatException if the value cannot be converted
*/
public static BigInteger createBigInteger(String val) {
BigInteger bi = new BigInteger(val);
return bi;
}
/**
* <p>Convert a <code>String</code> to a <code>BigDecimal</code>.</p>
*
* @param val a <code>String</code> to convert
* @return converted <code>BigDecimal</code>
* @throws NumberFormatException if the value cannot be converted
*/
public static BigDecimal createBigDecimal(String val) {
BigDecimal bd = new BigDecimal(val);
return bd;
}
//--------------------------------------------------------------------
/**
* <p>Checks whether the <code>String</code> contains only
* digit characters.</p>
*
* <p><code>Null</code> and empty String will return
* <code>false</code>.</p>
*
* @param str the <code>String</code> to check
* @return <code>true</code> if str contains only unicode numeric
*/
public static boolean isDigits(String str) {
if ((str == null) || (str.length() == 0)) {
return false;
}
for (int i = 0; i < str.length(); i++) {
if (!Character.isDigit(str.charAt(i))) {
return false;
}
}
return true;
}
}
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