I am looking for a simple, concise way to convert a given Number object to an object of a given numeric type.
I need something like:
private static Number convert(Number num, Class<? extends Number> targetType)
Is there a way to do it without checking all the combinations of types?
I think the clearest way is to use brute force:
private static Number convert(Number num, Class<? extends Number> targetType) {
Number result = null;
if (Byte.class.equals(targetType)) {
result = Byte.valueOf(num.byteValue());
} else if (Short.class.equals(targetType)) {
result = Short.valueOf(num.shortValue());
} else if (...) {
...
} else {
throw new IllegalArgumentException("targetType is not a Number");
}
return result;
}
You might use reflection, but I find that more hackish.
You can use something like:
String simpleName = targetType.getSimpleName().toLowerCase();
if (simpleName.equals("integer")) {
simpleName = "int";
}
Method m = number.getClass().getMethod(simpleName + "Value");
return (Number) m.invoke(number);
This relies on the fact that Number has methods like longValue(), floatValue(), etc.
As for BigInteger or AtomicInteger - you can use their constructor reflectively, which accepts one argument - the primitive type.
AtomicInteger, AtomicLong, BigDecimal, BigInteger, aren't passed in as targetType as they don't have a xxxValue() method on Number.Perhaps converting via BigDecimal would work?
public static <N extends Number> N convert(Number number, Class<N> type). This would return exactly the specified number type, which can have advantages in postprocessing.