在Groovy中向ArrayList动态添加元素 [英] Dynamically adding elements to ArrayList in Groovy

问题描述

我是Groovy的新手，尽管阅读了许多文章和关于此的问题，但我仍然不清楚发生了什么. 到目前为止，据我了解，当您在Groovy中创建新数组时，底层类型是Java ArrayList.这意味着它应该是可调整大小的，您应该能够将其初始化为空，然后通过add方法动态添加元素，如下所示:

MyType[] list = []
list.add(new MyType(...))

此编译，但是在运行时失败:方法的无签名:[LMyType; .add()适用于参数类型:(MyType)值:[MyType @ 383bfa16]

执行此操作的正确方法或正确类型是什么?

解决方案

使用Groovy的方法是

def list = []
list << new MyType(...)

创建一个列表并使用重载的列表上的文档. /p>

I am new to Groovy and, despite reading many articles and questions about this, I am still not clear of what is going on. From what I understood so far, when you create a new array in Groovy, the underlying type is a Java ArrayList. This means that it should be resizable, you should be able to initialize it as empty and then dynamically add elements through the add method, like so:

MyType[] list = []
list.add(new MyType(...))

This compiles, however it fails at runtime: No signature of method: [LMyType;.add() is applicable for argument types: (MyType) values: [MyType@383bfa16]

What is the proper way or the proper type to do this?

解决方案

The Groovy way to do this is

def list = []
list << new MyType(...)

which creates a list and uses the overloaded leftShift operator to append an item

See the Groovy docs on Lists for lots of examples.

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