如何将元素添加到Groovy中的列表中？ [英] How do I add an element to a list in Groovy?

问题描述

  def myList = [first，2 ，第三，4.0]; 
  

如何添加（推送）一个元素到最后？我来自PHP背景，在那里我只是做一些像 $ myList [] =fifth; 。什么是Groovy的等价物？

解决方案

从文档：

我们可以添加到列表在许多方面：

  assert [1,2] + 3 + [4,5] + 6 == [1,2,3,4,5,6] 
 assert [1,2] .plus（3）.plus（[4,5]）。plus（6）== [1 ，2，3，4，5，6] 
 //等价方法+ 
 def a = [1,2,3]; a + = 4; a + = [5,6]; assert a == [1,2,3,4,5,6] 
 assert [1，* [222，333]，456] == [1，222，333，456] 
 assert [* [1,2,3]] == [1,2,3] 
 assert [1，[2,3，[4,5]，6]，7，[8,9]]。 flatten（）== [1，2，3，4，5，6，7，8，9] 
 
 def list = [1,2] 
 list.add（3） //替代方法名称
 list.addAll（[5,4]）//替代方法名称
断言列表== [1,2,3,5,4] 
 
 list = [1,2] 
 list.add（1,3）//在索引1前添加3 
断言列表== [1,3,2] 
 list.addAll （2，[5,4]）//在索引2之前添加[5,4] 
断言列表== [1,3,5,4,2] 
 
 list = ['a'，'b'，'z'，'e'，'u'，'v'，'g'] 
 list [8] ='x'
断言列表== [ 'a'，'b'，'z'，'e'，'u'，'v'，'g'，null，'x'] 
   
 
您也可以这样做： 
 
 
  def myNewList = myList<< 第五
  
 
Let's say I've got a list, like this...
def myList = ["first", 2, "third", 4.0];
How do I add (push) an element to the end of it? I come from a PHP background, and there I would just do something like $myList[] = "fifth";. What's the equivalent of that in Groovy?
解决方案
From the documentation:

  
We can add to a list in many ways:


assert [1,2] + 3 + [4,5] + 6 == [1, 2, 3, 4, 5, 6]
assert [1,2].plus(3).plus([4,5]).plus(6) == [1, 2, 3, 4, 5, 6]
    //equivalent method for +
def a= [1,2,3]; a += 4; a += [5,6]; assert a == [1,2,3,4,5,6]
assert [1, *[222, 333], 456] == [1, 222, 333, 456]
assert [ *[1,2,3] ] == [1,2,3]
assert [ 1, [2,3,[4,5],6], 7, [8,9] ].flatten() == [1, 2, 3, 4, 5, 6, 7, 8, 9]

def list= [1,2]
list.add(3) //alternative method name
list.addAll([5,4]) //alternative method name
assert list == [1,2,3,5,4]

list= [1,2]
list.add(1,3) //add 3 just before index 1
assert list == [1,3,2]
list.addAll(2,[5,4]) //add [5,4] just before index 2
assert list == [1,3,5,4,2]

list = ['a', 'b', 'z', 'e', 'u', 'v', 'g']
list[8] = 'x'
assert list == ['a', 'b', 'z', 'e', 'u', 'v', 'g', null, 'x']
You can also do:
def myNewList = myList << "fifth"


                        
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