Try:

for (int i = 0; i < numbers.size(); i++) {
 float current_number = (Float)numbers.get(i);
}

float is a primitive data type.  You can't store primitives (float) in an ArrayList (ref 1), so you need to use a Float container instead of float.  Basically, Float is an object that represents float primitive (ref 2).

There is something called autoboxing in Java that allows you to freely convert Float to float without explicitly stating it, so you can do something like

Float f1 = 10f
float f2 = f1;


without a hitch. The reason you can't use (float) is that autoboxing is a process that's discrete from casting (more specifically, it's akin to a conversion from a "pointer" variable to an actual float value), and the compiler interprets them as such (ref 3).  Consequently, you need to .get() an object from the ArrayList, cast it into Object subclass (Float), and let the Float object autobox it into its primitive equivalent, which is float.


Of course, I'm assuming you've already used Float to store the values, so here is the complete demo:

import java.util.ArrayList;

ArrayList al = new ArrayList();

al.add(new Float(10f));
al.add(new Float(20f));

for(int i = 0; i < al.size(); i++){
 float f = (Float)al.get(i);
}

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ref 1:

http://java.sun.com/j2se/1.4.2/docs/api/java/util/ArrayList.html

ref 2:

http://java.sun.com/j2se/1.4.2/docs/api/java/lang/Float.html

ref 3:

http://java.sun.com/j2se/1.5.0/docs/guide/language/autoboxing.html