Java Object Type Case castToClass_strict(Number valueIn, Class toClassIn)

Description

Method for intelligently converting between Number classes.

License

Apache License

Parameter

Parameter	Description
valueIn	the number to convert
toClassIn	the desired class of the number

Return

the input number converted to the target class, or null if strict conversion is impossible

Declaration

public static Number castToClass_strict(Number valueIn, Class<? extends Number> toClassIn) 

Method Source Code

//package com.java2s;
/**/*from ww w .j  av  a  2 s  . co  m*/
 * Copyright 2014 opencxa.org
 *
 * Licensed 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.
 */

public class Main {
    private static final Double MAX_CAST_DELTA = .000001;

    /**
     * Method for intelligently converting between Number classes.
     * This method will attempt to convert the number with NO information
     * loss:
     * <p>
     * <b>Fractional Number -> Integer Number:</b>
     * If the fractional number (Double, Float) has a fractional component
     * this function will return null.
     * <p>
     * <b>Fraction Number -> Fractional Number</b>
     * If the difference between the result and the input is greater than {@link NumberUtils#MAX_CAST_DELTA}
     * this function will return null.
     * <p>
     * <b>General</b>
     * If the conversion will cause an overflow/underflow of the target number
     * type, this function will return null.
     * 
     * 
     * @param valueIn the number to convert
     * @param toClassIn the desired class of the number
     * 
     * @return the input number converted to the target class, or null
     *       if strict conversion is impossible
     */
    public static Number castToClass_strict(Number valueIn, Class<? extends Number> toClassIn) {
        if (valueIn == null)
            return null;

        if (valueIn.getClass() == toClassIn)
            return valueIn;

        boolean hasFractionalComponent = (Math.floor(valueIn.doubleValue()) != valueIn.doubleValue());

        // we can't convert a fractional component to an integer
        if (hasFractionalComponent && (toClassIn.equals(Byte.class) || toClassIn.equals(Short.class)
                || toClassIn.equals(Integer.class) || toClassIn.equals(Long.class)))
            return null;

        // now convert to a Double as our base class (everything _should_ be representable)
        Double base = valueIn.doubleValue();

        // now check our ranges or delta (based up on our output type)
        if (toClassIn.equals(Byte.class) && (base < Byte.MIN_VALUE) || (base > Byte.MAX_VALUE))
            return null;
        else if (toClassIn.equals(Short.class) && (base < Short.MIN_VALUE) || (base > Short.MAX_VALUE))
            return null;
        else if (toClassIn.equals(Integer.class) && (base < Integer.MIN_VALUE) || (base > Integer.MAX_VALUE))
            return null;
        else if (toClassIn.equals(Long.class) && (base < Long.MIN_VALUE) || (base > Long.MAX_VALUE))
            return null;
        else if (toClassIn.equals(Float.class) && (Math.abs((double) base.floatValue() - base) > MAX_CAST_DELTA))
            return null;

        // now actually perform our conversion
        Number retVal = null;
        {
            if (toClassIn.equals(Byte.class))
                retVal = Byte.valueOf(base.byteValue());
            else if (toClassIn.equals(Short.class))
                retVal = Short.valueOf(base.shortValue());
            else if (toClassIn.equals(Integer.class))
                retVal = Integer.valueOf(base.intValue());
            else if (toClassIn.equals(Long.class))
                retVal = Long.valueOf(base.longValue());
            else if (toClassIn.equals(Float.class))
                retVal = Float.valueOf(base.floatValue());
            else if (toClassIn.equals(Double.class))
                retVal = Double.valueOf(base.doubleValue());
        }
        return retVal;
    }
}

Related

1. castOrThrowError(Class clazz, T1 object, String messageTemplate)
2. castSafe(Class inClass, Object inValue, T inDefault)
3. caststring1(String tmpq)
4. castTo(Object o, Class cls)
5. castToArray(Object object)
6. castToObject(Object value)
7. castToPrimitive(Object value, String targetType)
8. castTotal(boolean isDoubleQuote, String target)
9. castToTypeOrNull(Object object, Class clazz)