Groovy(或Java)-通过引用传递给包装对象 [英] Groovy (or Java) - Pass by reference into a wrapper object

问题描述

在Java(或Groovy)中是否可以通过引用将对象传递给包装对象(即List或Map)?

Is it possible in Java (or Groovy) to pass an object by reference into a wrapper object (ie: List or Map)?

示例代码(在Groovy中):

Example code (in Groovy):

def object = null
def map = [object: object]
object = new Object()

不幸的是，即使object变量不存在，map.object仍为null，因此显然，地图的原始创建是通过值完成的，而不是通过引用完成的.

Unfortunately map.object remains null even though the object variable doesn't, so obviously the original creation of the map was done by value not by reference.

是否可以通过引用创建列表或地图，以便当列表或地图外部的对象发生更改时，更改会反映在包装对象内部?

Is it possible to create a List or Map via references so that when the object outside the List or Map changes the change is reflected inside the wrapper object?

推荐答案

您可以使用闭包，但是需要调用它们:

You can with closures, but they need to be invoked:

def object = null
def map = [object: { object }]
object = new Object()

assert map.object() != null

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