为什么Java除以0.0时不会抛出异常？-Whydoesn'tJavathrowanExceptionwhendividingby0.0?

43  

The result of division by zero is, mathematically speaking, undefined, which can be expressed with a float/double (as NaN - not a number), it isn't, however, wrong in any fundamental sense.

从数学上讲，除以零的结果是未定义的，可以用float / double表示（如NaN - 不是数字），但在任何基本意义上都不是错误的。

As an integer must hold a specific numerical value, an error must be thrown on division by zero when dealing with them.

由于整数必须包含特定的数值，因此在处理它们时必须将除以零的错误抛出。

106  

Java's float and double types, like pretty much any other language out there (and pretty much any hardware FP unit), implement the IEEE 754 standard for floating point math, which mandates division by zero to return a special "infinity" value. Throwing an exception would actually violate that standard.

Java的float和double类型，就像其他任何语言（以及几乎任何硬件FP单元）一样，实现了浮点数学的IEEE 754标准，它要求除以零以返回特殊的“无穷大”值。抛出异常实际上会违反该标准。

Integer arithmetic (implemented as two's complement representation by Java and most other languages and hardware) is different and has no special infinity or NaN values, thus throwing exceptions is a useful behaviour there.

整数算术（由Java和大多数其他语言和硬件实现为二进制补码表示）是不同的，没有特殊的无穷大或NaN值，因此抛出异常是一种有用的行为。

4  

The way a double is stored is quite different to an int. See http://firstclassthoughts.co.uk/java/traps/java_double_traps.html for a more detailed explanation on how Java handles double calculations. You should also read up on Floating Point numbers, in particular the concept of Not a Number (NaN).

存储double的方式与int完全不同。有关Java如何处理双重计算的更详细说明，请参见http://firstclassthoughts.co.uk/java/traps/java_double_traps.html。您还应该阅读浮点数，特别是非数字（NaN）的概念。

If you're interested in learning more about floating point representation, I'd advise reading this document (Word format, sorry). It delves into the binary representation of numbers, which may be helpful to your understanding.

如果您有兴趣了解有关浮点表示的更多信息，我建议您阅读本文档（Word格式，抱歉）。它深入研究数字的二进制表示，这可能有助于您的理解。

3  

Though Java developers know about the double primitive type and Double class, while doing floating point arithmetic they don't pay enough attention to Double.INFINITY, NaN, -0.0 and other rules that govern the arithmetic calculations involving them.

虽然Java开发人员知道双原语类型和Double类，但在进行浮点运算时，他们没有足够重视Double.INFINITY，NaN，-0.0和其他规则来控制涉及它们的算术计算。

The simple answer to this question is that it will not throw ArithmeticException and return Double.INFINITY. Also, note that the comparison x == Double.NaN always evaluates to false, even if x itself is a NaN.

这个问题的简单答案是它不会抛出ArithmeticException并返回Double.INFINITY。另外，请注意，即使x本身是NaN，比较x == Double.NaN也始终求值为false。

To test if x is a NaN, one should use the method call Double.isNaN(x) to check if given number is NaN or not. This is very close to NULL in SQL.

要测试x是否为NaN，应该使用方法调用Double.isNaN（x）来检查给定的数字是否为NaN。这在SQL中非常接近NULL。

It may helpful for you.

它可能对你有帮助。

1  

When divided by zero ( 0 or 0.00 )

除以零（0或0.00）时

1. If you divide double by 0, JVM will show Infinity.

   如果将double除以0，JVM将显示Infinity。

   public static void main(String [] args){ double a=10.00; System.out.println(a/0); }

   public static void main（String [] args）{double a = 10.00;的System.out.println（A / 0）; }

   Console: Infinity

   控制台：无限

2. If you divide int by 0, then JVM will throw Arithmetic Exception.

   如果将int除以0，则JVM将抛出算术异常。

   public static void main(String [] args){ int a=10; System.out.println(a/0); }

   public static void main（String [] args）{int a = 10;的System.out.println（A / 0）; }

   Console: Exception in thread "main" java.lang.ArithmeticException: / by zero

   控制台：线程“main”中的异常java.lang.ArithmeticException：/ by zero

3. But if we divide int by 0.0, then JVM will show Infinity:

   但是如果我们将int除以0.0，那么JVM将显示Infinity：

   public static void main(String [] args){ int a=10; System.out.println(a/0.0); }

   public static void main（String [] args）{int a = 10;的System.out.println（A / 0.0）; }

   Console: Infinity

   控制台：无限

This is because JVM will automatically type cast int to double, so we get infinity instead of ArithmeticException.

这是因为JVM会自动将cast int类型化为double，因此我们得到无穷大而不是ArithmeticException。