为什么 Java 中没有 ceil(float)？
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Why is there no ceil(float) in Java?
提问by Michael
Suppose I would like to round up floatto intin Java.
For instance,
假设我想四舍五入float到intin Java。
例如，
roundUp(0.2) = 1
roundUp(0.7) = 1
roundUp(1.3) = 2
...
I would like to call Math.ceiland Math.roundto do that but java.lang.Mathdoes not provide ceil(float). It provides only ceil(double). So my floatis promoted to doublesilently, ceil(double)returns doubleand round(double)returns longwhile I need to round up floatto int(not long).
我想打电话Math.ceil并Math.round这样做，但java.lang.Math没有提供ceil(float)。它仅提供ceil(double). 所以 myfloat被提升为double静默，ceil(double)返回double并round(double)返回，long而我需要四舍五入float到int(not long)。
Now I wonder why java.lang.Mathhas only ceil(double)and does not have ceil(float).
现在我想知道为什么java.lang.Math只有ceil(double)和没有ceil(float)。
回答by Simeon Visser
You can do:
你可以做：
value = (int) Math.ceil(value);
If you know that valueis a float then you can cast the result back to floator int.
如果您知道这value是一个浮点数，那么您可以将结果转换回floator int。
It makes no sense for the Java library to provide both ceil(float)and ceil(double)as all float arguments can be passed to the ceil(double)method with the same result.
Java 库提供这两者是没有意义的ceil(float)，ceil(double)因为所有浮点参数都可以传递给ceil(double)具有相同结果的方法。
