在 Java 中，如何检查浮点变量是否为空？
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In Java, how do you check if a float variable is null?
提问by Christopher Treanor
It seems that when it comes to *value.getFloat("Value_Quotient", quotient_Float)==null*, it encounters a problem. How do I fix this?
好像说到*value.getFloat("Value_Quotient", quotient_Float)==null*，就遇到了问题。我该如何解决？
private void Store() {
quotient_Float = posture_error/time;
if(value.getFloat("Value_Quotient", quotient_Float)==null || quotient_Float < value.getFloat("Value_Quotient", quotient_Float))
{
editor.putFloat("Value_Quotient", quotient_Float);
editor.commit();
}
}
采纳答案by Juned Ahsan
floatis a primitivedata type and not an object. null check is used for objects. For primitives you should use the default values check. For float the default value is 0.0f.
float是一种primitive数据类型而不是object. 空检查用于对象。对于基元，您应该使用默认值检查。对于浮点数，默认值为 0.0f。
回答by Jason Crosby
There is also a Floatclass that you can use. The Floatobject can be checked for nullas its an object representation of a floatdata type. A Floatobject is represented by a capitol F, and the floatdata type has a small f. Java preforms autoboxing, which means that you can easily switch back and fourth between the two, i.e:
还有一个浮动类，您可以使用。所述Float对象可以检查null作为其的对象表示float的数据类型。一个Float对象用大写字母 F 表示，float数据类型有一个小的 f。Java 预制自动装箱，这意味着您可以轻松地在两者之间来回切换，即：
float number = 0.56f;
Float object = number;
Or the other way around:
或者反过来：
Float object = new Float(1.43);
float number = object;
You can also pass a Floatobject into a method where a floatdata type is expected, or the other way around.
您还可以将Float对象传递到需要float数据类型的方法中，或者反过来。
If checking for the default value doesnt work for whatever reason, this will allow you to check a Floatfor null.
如果出于某种原因检查默认值不起作用，这将允许您检查Float空值。
if (object != null) {
// do what you want to do
}
回答by Dmitry Avgustis
Some points that might be useful(Java 8).
一些可能有用的要点（Java 8）。
Float object can be assigned to a float primitive. Then float primitive can be 0 checked like this:
浮点对象可以分配给浮点基元。然后可以像这样检查浮点基元 0：
Float floatObj = new Float(0);
float floatPrim = floatObj;
if (floatPrim == 0) {
System.out.println("floatPrim is 0"); // will display message
}
However if your Float object is null, than assigning it to a primitive will cause NPE
但是，如果您的 Float 对象为空，那么将其分配给原语会导致 NPE
Float floatObj = null;
float floatPrim = floatObj; //NPE
So be careful here
所以在这里要小心
One more thing, apparently you can use == operator on Float object, since autounboxing happens.
还有一件事，显然你可以在 Float 对象上使用 == 运算符，因为自动拆箱发生了。
Float floatObj = new Float(0.0f);
if (floatObj == 0) {
System.out.println("floatObj is 0"); // will work
}
