Convert the given number into an instance of the given target class. : Number « Data Type « Java
Convert the given number into an instance of the given target class.
/*
* Copyright 2002-2006 the original author or authors.
*
* 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.
*/
//package jacky.lanlan.song.extension.struts.util;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.text.NumberFormat;
import java.text.ParseException;
/**
* Miscellaneous utility methods for number conversion and parsing.
* Mainly for internal use within the framework; consider Jakarta's
* Commons Lang for a more comprehensive suite of string utilities.
*
* @author Juergen Hoeller
* @author Rob Harrop
* @since 1.1.2
*/
public abstract class NumberUtils {
/**
* Convert the given number into an instance of the given target class.
* @param number the number to convert
* @param targetClass the target class to convert to
* @return the converted number
* @throws IllegalArgumentException if the target class is not supported
* (i.e. not a standard Number subclass as included in the JDK)
* @see java.lang.Byte
* @see java.lang.Short
* @see java.lang.Integer
* @see java.lang.Long
* @see java.math.BigInteger
* @see java.lang.Float
* @see java.lang.Double
* @see java.math.BigDecimal
*/
public static Number convertNumberToTargetClass(Number number, Class<?> targetClass)
throws IllegalArgumentException {
// Assert.notNull(number, "Number must not be null");
// Assert.notNull(targetClass, "Target class must not be null");
if (targetClass.isInstance(number)) {
return number;
}
else if (targetClass.equals(Byte.class)) {
long value = number.longValue();
if (value < Byte.MIN_VALUE || value > Byte.MAX_VALUE) {
raiseOverflowException(number, targetClass);
}
return new Byte(number.byteValue());
}
else if (targetClass.equals(Short.class)) {
long value = number.longValue();
if (value < Short.MIN_VALUE || value > Short.MAX_VALUE) {
raiseOverflowException(number, targetClass);
}
return new Short(number.shortValue());
}
else if (targetClass.equals(Integer.class)) {
long value = number.longValue();
if (value < Integer.MIN_VALUE || value > Integer.MAX_VALUE) {
raiseOverflowException(number, targetClass);
}
return new Integer(number.intValue());
}
else if (targetClass.equals(Long.class)) {
return new Long(number.longValue());
}
else if (targetClass.equals(Float.class)) {
return new Float(number.floatValue());
}
else if (targetClass.equals(Double.class)) {
return new Double(number.doubleValue());
}
else if (targetClass.equals(BigInteger.class)) {
return BigInteger.valueOf(number.longValue());
}
else if (targetClass.equals(BigDecimal.class)) {
// using BigDecimal(String) here, to avoid unpredictability of BigDecimal(double)
// (see BigDecimal javadoc for details)
return new BigDecimal(number.toString());
}
else {
throw new IllegalArgumentException("Could not convert number [" + number + "] of type [" +
number.getClass().getName() + "] to unknown target class [" + targetClass.getName() + "]");
}
}
/**
* Raise an overflow exception for the given number and target class.
* @param number the number we tried to convert
* @param targetClass the target class we tried to convert to
*/
private static void raiseOverflowException(Number number, Class<?> targetClass) {
throw new IllegalArgumentException("Could not convert number [" + number + "] of type [" +
number.getClass().getName() + "] to target class [" + targetClass.getName() + "]: overflow");
}
}
