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[]
3 Answers
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();
2 Comments
PawelP
Such a bummer. That used to be so easy in C#.
Mickael Bergeron Néron
In days like this I hate Java.
You can use Apache Commons ArrayUtils.toPrimitive():
List<Float> list = new ArrayList<Float>();
float[] floatArray = ArrayUtils.toPrimitive(list.toArray(new Float[0]), 0.0F);
2 Comments
Hephaestus
Link above is broken. I used the following import:
import org.apache.commons.lang3.ArrayUtils;
Galigator
list.toArray(...) will create an intermediate array... while the simple loop over the list won't.
int s=list.size(); float[] a = new float[s]; for (int i=0;i<s;i++) a[i]=list.get(i);