numberutils.java

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 *       "This product includes software developed by the
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package org.apache.commons.lang.math;

import java.math.BigDecimal;
import java.math.BigInteger;

import org.apache.commons.lang.StringUtils;

/**
 * <p>Provides extra functionality for Java Number classes.</p>
 *
 * @author <a href="mailto:[e-mail]">Henri Yandell</a>
 * @author <a href="mailto:[e-mail]">Rand McNeely</a>
 * @author Stephen Colebourne
 * @author <a href="mailto:[e-mail]">Steve Downey</a>
 * @author Eric Pugh
 * @author Phil Steitz
 * @author Matthew Hawthorne
 * @author <a href="mailto:[e-mail]">Gary Gregory</a>
 * @since 2.0
 * @version $Id: NumberUtils.java,v 1.10 2003/08/18 02:22:24 bayard Exp $
 */
public class NumberUtils {
    
    /** Reusable Long constant for zero. */
    public static final Long LONG_ZERO = new Long(0L);
    /** Reusable Long constant for one. */
    public static final Long LONG_ONE = new Long(1L);
    /** Reusable Long constant for minus one. */
    public static final Long LONG_MINUS_ONE = new Long(-1L);
    /** Reusable Integer constant for zero. */
    public static final Integer INTEGER_ZERO = new Integer(0);
    /** Reusable Integer constant for one. */
    public static final Integer INTEGER_ONE = new Integer(1);
    /** Reusable Integer constant for minus one. */
    public static final Integer INTEGER_MINUS_ONE = new Integer(-1);
    /** Reusable Short constant for zero. */
    public static final Short SHORT_ZERO = new Short((short) 0);
    /** Reusable Short constant for one. */
    public static final Short SHORT_ONE = new Short((short) 1);
    /** Reusable Short constant for minus one. */
    public static final Short SHORT_MINUS_ONE = new Short((short) -1);
    /** Reusable Byte constant for zero. */
    public static final Byte BYTE_ZERO = new Byte((byte) 0);
    /** Reusable Byte constant for one. */
    public static final Byte BYTE_ONE = new Byte((byte) 1);
    /** Reusable Byte constant for minus one. */
    public static final Byte BYTE_MINUS_ONE = new Byte((byte) -1);
    /** Reusable Double constant for zero. */
    public static final Double DOUBLE_ZERO = new Double(0.0d);
    /** Reusable Double constant for one. */
    public static final Double DOUBLE_ONE = new Double(1.0d);
    /** Reusable Double constant for minus one. */
    public static final Double DOUBLE_MINUS_ONE = new Double(-1.0d);
    /** Reusable Float constant for zero. */
    public static final Float FLOAT_ZERO = new Float(0.0f);
    /** Reusable Float constant for one. */
    public static final Float FLOAT_ONE = new Float(1.0f);
    /** Reusable Float constant for minus one. */
    public static final Float FLOAT_MINUS_ONE = new Float(-1.0f);

    /**
     * <p><code>NumberUtils</code> instances should NOT be constructed in standard programming.
     * Instead, the class should be used as <code>NumberUtils.stringToInt("6");</code>.</p>
     *
     * <p>This constructor is public to permit tools that require a JavaBean instance
     * to operate.</p>
     */
    public NumberUtils() {
    }

    //-----------------------------------------------------------------------
    /**
     * <p>Convert a <code>String</code> to an <code>int</code>, returning
     * <code>zero</code> if the conversion fails.</p>
     *
     * <p>If the string is <code>null</code>, <code>zero</code> is returned.</p>
     * 
     * @param str  the string to convert, may be null
     * @return the int represented by the string, or <code>zero</code> if
     *  conversion fails
     */
    public static int stringToInt(String str) {
        return stringToInt(str, 0);
    }

    /**
     * <p>Convert a <code>String</code> to an <code>int</code>, returning a
     * default value if the conversion fails.</p>
     *
     * <p>If the string is <code>null</code>, the default value is returned.</p>
     * 
     * @param str  the string to convert, may be null
     * @param defaultValue  the default value
     * @return the int represented by the string, or the default if conversion fails
     */
    public static int stringToInt(String str, int defaultValue) {
        try {
            return Integer.parseInt(str);
        } catch (NumberFormatException nfe) {
            return defaultValue;
        }
    }

    //-----------------------------------------------------------------------
    // 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 represent 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>
     *
     * <p>Returns <code>null</code> if the string is <code>null</code>.</p>
     *
     * <p>This method does not trim the input string, i.e., strings with leading
     * or trailing spaces will generate NumberFormatExceptions.</p>
     *
     * @param str  String containing a number, may be null
     * @return Number created from the string
     * @throws NumberFormatException if the value cannot be converted
     */
    public static Number createNumber(String str) throws NumberFormatException {
        if (str == null) {
            return null;
        }
        if (StringUtils.isBlank(str)) {
            throw new NumberFormatException("A blank string is not a valid number");
        }  
        if (str.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 (str.startsWith("0x") || str.startsWith("-0x")) {
            return createInteger(str);
        }   
        char lastChar = str.charAt(str.length() - 1);
        String mant;
        String dec;
        String exp;
        int decPos = str.indexOf('.');
        int expPos = str.indexOf('e') + str.indexOf('E') + 1;

        if (decPos > -1) {

            if (expPos > -1) {
                if (expPos < decPos) {
                    throw new NumberFormatException(str + " is not a valid number.");
                }
                dec = str.substring(decPos + 1, expPos);
            } else {
                dec = str.substring(decPos + 1);
            }
            mant = str.substring(0, decPos);
        } else {
            if (expPos > -1) {
                mant = str.substring(0, expPos);
            } else {
                mant = str;
            }
            dec = null;
        }
        if (!Character.isDigit(lastChar)) {
            if (expPos > -1 && expPos < str.length() - 1) {
                exp = str.substring(expPos + 1, str.length() - 1);
            } else {
                exp = null;
            }
            //Requesting a specific type..
            String numeric = str.substring(0, str.length() - 1);
            boolean allZeros = isAllZeros(mant) && isAllZeros(exp);
            switch (lastChar) {
                case 'l' :
                case 'L' :
                    if (dec == null
                        && exp == null
                        && isDigits(numeric.substring(1))
                        && (numeric.charAt(0) == '-' || Character.isDigit(numeric.charAt(0)))) {
                        try {
                            return createLong(numeric);
                        } catch (NumberFormatException nfe) {
                            //Too big for a long
                        }
                        return createBigInteger(numeric);

                    }
                    throw new NumberFormatException(str + " is not a valid number.");
                case 'f' :
                case 'F' :
                    try {
                        Float f = NumberUtils.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 doens't have the presision we want
                            return f;
                        }

                    } catch (NumberFormatException nfe) {
                    }
                    //Fall through
                case 'd' :
                case 'D' :
                    try {
                        Double d = NumberUtils.createDouble(numeric);
                        if (!(d.isInfinite() || (d.floatValue() == 0.0D && !allZeros))) {
                            return d;
                        }
                    } catch (NumberFormatException nfe) {
                    }
                    try {
                        return createBigDecimal(numeric);
                    } catch (NumberFormatException e) {
                    }
                    //Fall through
                default :
                    throw new NumberFormatException(str + " 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 < str.length() - 1) {
                exp = str.substring(expPos + 1, str.length());
            } else {
                exp = null;
            }
            if (dec == null && exp == null) {
                //Must be an int,long,bigint
                try {
                    return createInteger(str);
                } catch (NumberFormatException nfe) {
                }
                try {
                    return createLong(str);
                } catch (NumberFormatException nfe) {
                }
                return createBigInteger(str);

            } else {
                //Must be a float,double,BigDec
                boolean allZeros = isAllZeros(mant) && isAllZeros(exp);
                try {
                    Float f = createFloat(str);
                    if (!(f.isInfinite() || (f.floatValue() == 0.0F && !allZeros))) {
                        return f;
                    }
                } catch (NumberFormatException nfe) {
                }
                try {
                    Double d = createDouble(str);
                    if (!(d.isInfinite() || (d.doubleValue() == 0.0D && !allZeros))) {
                        return d;
                    }
                } catch (NumberFormatException nfe) {
                }

                return createBigDecimal(str);

            }
        }
    }

    /**
     * <p>Utility method for {@link #createNumber(java.lang.String)}.</p>
     *
     * <p>Returns <code>true</code> if s is <code>null</code>.</p>
     * 
     * @param str  the String to check
     * @return if it is all zeros or <code>null</code>
     */
    private static boolean isAllZeros(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;
    }

    //-----------------------------------------------------------------------
    /**
     * <p>Convert a <code>String</code> to a <code>Float</code>.</p>
     *
     * <p>Returns <code>null</code> if the string is <code>null</code>.</p>
     * 
     * @param str  a <code>String</code> to convert, may be null
     * @return converted <code>Float</code>
     * @throws NumberFormatException if the value cannot be converted
     */
    public static Float createFloat(String str) {
        if (str == null) {
            return null;
        }
        return Float.valueOf(str);
    }

    /**
     * <p>Convert a <code>String</code> to a <code>Double</code>.</p>
     * 
     * <p>Returns <code>null</code> if the string is <code>null</code>.</p>
     *
     * @param str  a <code>String</code> to convert, may be null
     * @return converted <code>Double</code>
     * @throws NumberFormatException if the value cannot be converted
     */
    public static Double createDouble(String str) {
        if (str == null) {