Double selection combo box in Struts2

Below, I tried to see if the list contains two items

s:doubleselect label="doubleselect test1" name="menu" list="{'fruit','other'}" 
doubleName="dishes" doubleList="top == 'fruit'开发者_如何转开发 ? {'apple', 'orange'} : 
{'monkey', 'chicken'}"

If the list containts three or more items {'fruit','flower','other'} what should be syntax for doubleList?

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See this example: http://www.mkyong.com/struts2/struts-2-sdoubleselect-example/