添加到列表中速度真实显示 [英] Adding to List Prints true in Velocity

问题描述

我正在尝试将一些字符串值添加到Velocity中的列表中.当我运行代码时，它可以正常工作.但是添加值的行显示为true.在Velocity中总是这样吗?我是Velocity模板的新手，所以自己无法弄清楚.

I am trying to add some string values to a list in Velocity. When I run the code it works alright. But the line where it adds the value prints true. Is it always like that in Velocity? I am new to Velocity templates, so cant figure it out myself.

#set ($uniqueInterfaces     =   [])
#if($ipv4interfaceName == $ipv6interfaceName)
    $uniqueInterfaces.add($ipv4interfaceName)
#end

它是带有嵌套foreach的较大代码的一部分.它有两个匹配项，因此输出为:

Its part of larger code with a nested foreach. It has two matches in it, so the output is:

true
true

我根本不需要打印出这个真实的东西！

I do not need this true being printed at all!

推荐答案

Java的

Java's List#add method returns boolean, that's why this return value is printed in your html output.

您只需将add方法的输出分配给虚拟变量即可将其隐藏:

You can hide it simply by assigning the output of the add method to a dummy variable:

#set ($uniqueInterfaces     =   [])
#if($ipv4interfaceName == $ipv6interfaceName)
    #set ($swallow = $uniqueInterfaces.add($ipv4interfaceName))
#end

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