如何在groovy中组合数组？

Question

存在以下java代码,但我正在尝试将其转换为groovy.我应该像使用System.arraycopy一样保持它,还是groovy有一个更好的方法来组合这样的数组？

  byte[] combineArrays(foo, bar, start) {
    def tmp = new byte[foo.length + bar.length]
    System.arraycopy(foo, 0, tmp, 0, start)
    System.arraycopy(bar, 0, tmp, start, bar.length)
    System.arraycopy(foo, start, tmp, bar.length + start, foo.length - start)
    tmp
  }

谢谢

Answer 1

def a = [1, 2, 3]
def b = [4, 5, 6]

assert a.plus(b) == [1, 2, 3, 4, 5, 6]   
assert a + b     == [1, 2, 3, 4, 5, 6]

Answer 2

如果要使用数组:

def abc = [1,2,3,4] as Integer[] //Array
def abcList = abc as List
def xyz = [5,6,7,8] as Integer[] //Array
def xyzList = xyz as List

def combined = (abcList << xyzList).flatten()

使用列表:

def abc = [1,2,3,4]
def xyz = [5,6,7,8]
def combined = (abc << xyz).flatten()

Answer 3

def a = [1, 2, 3]
def b = [4, 5, 6]
a.addAll(b)
println a

>> [1, 2, 3, 4, 5, 6]

Answer 4

我会去的

byte[] combineArrays(foo, bar, int start) {
  [*foo[0..<start], *bar, *foo[start..<foo.size()]]
}

Answer 5

诀窍是 flatten() 方法，它将嵌套数组合并为一个：

def a = [1, 2, 3]
def b = [4, 5, 6]
def combined = [a, b].flatten()

assert combined == [1, 2, 3, 4, 5, 6]

println(combined)

要删除空值，您可以像这样使用 findAll()：

def a = null
def b = [4, 5, 6]
def combined = [a, b].flatten().findAll{it}

assert combined == [4, 5, 6]

println(combined)