Create a Bar Chart from a list/array

I have a variable of type List (ArrayList in fact) that contains numbers. How can I plot that numbers in a Bar Chart? What should I enter in Series Category Expression?

Complete story:

I'm using an XML datasource. One of its fields is:

<values>48,59,59,58,53,53,52,55,50,52,54,56,57,59,60,57,56,55,58,62</values>

So I've created a variable with those values splitted like this:

<variable name="arraylist" class="java.util.List">
<variableExpression><![CDATA[new
ArrayList<>(Arrays.asList($F{values}.split(",")))]]></variableExpression>
</variable>

Now I want to plot the values in a Bar Chart but... what should I write here?

The list of values will always have 20 values (size=20), if that simplifies the problem.