How I can do that?
I have an arraylist, with float elements. (Arraylist <Float>)
(float[]) Floats_arraylist.toArray()
it is not working.
cannot cast from Object[] to float[]
You can't. A list of Float can only, logically, contain Floats.
Loop over it yourself.
List<Float> floatList = getItSomehow(); float[] floatArray = new float[floatList.size()]; int i = 0; for (Float f : floatList) { floatArray[i++] = (f != null ? f : Float.NaN); // Or whatever default you want. }
The nullcheck is mandatory to avoid NullPointerException
because a Float
(an object) can be null
while a float
(a primitive) cannot be null
at all.
In case you're on Java 8 already and it's no problem to end up with double[]
instead of float[]
, consider Stream#mapToDouble()
(no there's no such method as mapToFloat()
).
List<Float> floatList = getItSomehow(); double[] doubleArray = floatList.stream() .mapToDouble(f -> f != null ? f : Float.NaN) // Or whatever default you want. .toArray();
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