Main.java Source code

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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;
    }
}