What is the best way to access an array inside Velocity?

问题

I have a Java array such as:

String[] arr = new String[] {"123","doc","projectReport.doc"};

In my opinion the natural way to access would be:

 #set($att_id = $arr[0])
 #set($att_type = $arr[1])
 #set($att_name = $arr[2])

But that it is not working. I have come with this workaround. But it a bit too much code for such an easy task.

#set($counter = 0)
#foreach($el in $arr)
    #if($counter==0)
        #set($att_id = $el)
    #elseif($counter==1)
        #set($att_type = $el)
    #elseif($counter==2)
         #set($att_name = $el)
    #end
    #set($counter = $counter + 1)
#end

Is there any other way?

回答1:

You can use use Velocity 1.6: for an array named $array one can simply do $array.get($index).

In the upcoming Velocity 1.7, one will be able to do $array[$index] (as well as $list[$index] and $map[$key]).

回答2:

You could wrap the array in a List using Arrays.asList(T... a). The new List object is backed by the original array so it doesn't wastefully allocate a copy. Even changes made to the new List will propagate back to the array.

Then you can use $list.get(int index) to get your objects out in Velocity.

If you need to get just one or two objects from an array, you can also use Array.get(Object array, int index) to get an item from an array.

回答3:

String[] arr = new String[] {"123", "doc", "projectReport.doc"};

In my opinion the natural way to access would be:

 #set($att_id = $arr[0]) 
 #set($att_type = $arr[1]) 
 #set($att_name = $arr[2])

The value for this can be get by using $array.get("arr", 1) because there is no direct way to get the value from array like $att_id = $arr[0] in velocity.
Hope it works :)

回答4:

there is an implicit counter $velocityCount which starts with value 1 so you do not have to create your own counter.

回答5:

Brian's answer is indeed correct, although you might like to know that upcoming Velocity 1.6 has direct support for arrays; see the Velocity documentation for more information.

回答6:

Velocity 1.6

$myarray.isEmpty()
$myarray.size()
$myarray.get(2)
$myarray.set(1, 'test')

http://velocity.apache.org/engine/1.7/user-guide.html

回答7:

I ended up using the ListTool from the velocity-tools.jar. It has methods to access an array's elements and also get its size.

回答8:

I has the same question and it got answered on another thread

#set ( $Page = $additionalParams.get('Page') )
#set ( $Pages = [] )
#if ( $Page != $null && $Page != "" )
    #foreach($i in $Page.split(";"))
        $Pages.add($i)
    #end
#end

Array indexing in Confluence / Velocity templates

来源：https://stackoverflow.com/questions/191844/what-is-the-best-way-to-access-an-array-inside-velocity

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velocity