Java Longs中的Fibonacci计算显示为负数 [英] Fibonacci calculation in Java Longs shows up negative

问题描述

我的Fibonacci计算器工作正常，但是当达到更高的数字时，结果会显示为负数，因为如果它是整数超过其最大值。

My Fibonacci calculator works fine, but when going up to higher numbers the result comes up negative, as it would if it was an Integer over its max value.

它使用缓存 java.util.Map< Integer，Long> 。进入地图的所有内容都是预期的，但是当打印出来时，我得到了对于291：

It is working with a cache java.util.Map<Integer, Long>. Everything that goes into the Map is exactly what is expected, but when printing it out I get e.g. for 291:

-784134397488903422

根据 http ：//www.maths.surrey.ac.uk/hosted-sites/R.Knott/Fibonacci/fibCalcX.html ，它应该是：

2923602405716568564338475449381171413803636207598822186175234

我的<$ c $似乎出了问题c>长 s，但我不确定，到底是什么。有人可以指出我正确的方向吗？

It seems something goes wrong with my Longs, but I am not sure yet, what exactly. Could someone please point me in the right direction?

地图条目的值：
http://pastebin.com/uje07Ays

推荐答案

我认为你高于可以存储在Java用于long类型的有符号64位整数中的最大long值，有关Long和Java API的更多信息： http://docs.oracle.com/javase/7/docs/api/java /lang/Long.html 。

I think you are above the maximum long value that can be stored in a signed 64 bits integer used by Java for the long type, more information about Long and thesein the Java API: http://docs.oracle.com/javase/7/docs/api/java/lang/Long.html.

64位有符号整数的最大正值为2 ^ 63 -1： 9 223 372 036 854 775 807 ，您的值似乎已达到此限制，如果有符号整数的最高位为1，则有符号整数将变为负数（有关详细信息，请参阅2补码整数： http://en.wikipedia.org/wiki/Two%27s_complement ）。

The maximum positive value for a 64 bits signed integer is 2^63 -1: 9 223 372 036 854 775 807, your value seems to have reach this limit and if the highest bit of a signed integer is 1, then the signed integer become negative (see 2 complement integer for more details: http://en.wikipedia.org/wiki/Two%27s_complement).

您需要使用BigInteger来获得任意精度的整数 http ：//docs.oracle.com/javase/7/docs/api/java/math/BigInteger.html 。

You need to use BigInteger to have arbitrary-precision integers http://docs.oracle.com/javase/7/docs/api/java/math/BigInteger.html.

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