java 检查对象是否是任何“数字”类的实例？

Check if object is instance of any 'number' class?

提问by fweigl

Object o = ?
if ((o instanceof Integer) || (o instanceof Double) || (o instanceof Float)|| (o instanceof Long))

Is there a shorter version to check if an Object is any of the Number types?

是否有更短的版本来检查对象是否是任何数字类型？

回答by Peter Lawrey

You can do

你可以做

if (o instanceof Number) {
    Number num = (Number) o;

If you only have the class you can do

如果你只有这门课，你可以做

Class clazz = o.getClass();
if (Number.class.isAssignableFrom(clazz)) {

Note: this treats Byte, Short, BigIntegerand BigDecimalas numbers.

注：此治疗Byte，Short，BigInteger并BigDecimal为数字。

If you look at the Javadoc for Integeryou can see its parent is Numberwhich in turn has the sub-classes AtomicInteger, AtomicLong, BigDecimal, BigInteger, Byte, Double, DoubleAccumulator, DoubleAdder, Float, Integer, Long, LongAccumulator, LongAdder, Shortso instance Numberwill match any of these.

如果您查看Integer的Javadoc，您会看到它的父类是Number，它又具有子类，AtomicInteger, AtomicLong, BigDecimal, BigInteger, Byte, Double, DoubleAccumulator, DoubleAdder, Float, Integer, Long, LongAccumulator, LongAdder, Short因此instance Number将匹配其中的任何一个。