如何在Java中实现无穷大？

Question

Java是否有能代表每种数值数据类型的无穷大？它是如何实现的,以便我可以用它进行数学运算？

例如

int myInf = infinity; //However it is done
myInf + 5; //returns infinity
myInf*(-1); //returns negative infinity

我尝试使用非常大的数字,但我想要一个合适的,简单的解决方案.

Answer 1

double 支持无限

double inf = Double.POSITIVE_INFINITY;
System.out.println(inf + 5);
System.out.println(inf - inf); // same as Double.NaN
System.out.println(inf * -1); // same as Double.NEGATIVE_INFINITY

版画

Infinity
NaN
-Infinity

注意:Infinity - Infinity是不是一个数字.

Answer 2

我假设你使用整数数学是有原因的.如果是这样,您可以通过使用类的MAX_VALUE字段获得与POSITIVE_INFINITY功能几乎相同的结果Integer:

Integer myInf = Integer.MAX_VALUE;

(对于NEGATIVE_INFINITY,您可以使用MIN_VALUE.)当然会有一些功能上的差异,例如,当比较myInf恰好是MAX_VALUE的值时:显然这个数字不小于myInf.

还有一个库实际上有字段POSITIVE_INFINITY和NEGATIVE_INFINITY,但它们实际上只是MAX_VALUE和MIN_VALUE的新名称.

Answer 3

要使用Infinity,您可以使用Double哪些支持Infinity: -

    System.out.println(Double.POSITIVE_INFINITY);
    System.out.println(Double.POSITIVE_INFINITY * -1);
    System.out.println(Double.NEGATIVE_INFINITY);

    System.out.println(Double.POSITIVE_INFINITY - Double.NEGATIVE_INFINITY);
    System.out.println(Double.POSITIVE_INFINITY - Double.POSITIVE_INFINITY);

输出: -

Infinity
-Infinity
-Infinity

Infinity 
NaN

Answer 4

整数无穷大：

  Integer maxNumber = Integer.MAX_VALUE

双无穷大

  Double maxNumber = Double.MAX_VALUE;
  Double positiveInf = Double.POSITIVE_INFINITY;
  Double negativeInf = Double.NEGATIVE_INFINITY

浮动无穷大

   Float positiveInf = Float.POSITIVE_INFINITY;
   Float negativeInf = Float.NEGATIVE_INFINITY
   Float maxNumber = Float.MAX_VALUE;

Answer 5

该Double和Float类型具有POSITIVE_INFINITY恒定的。