Jenkinsfile嵌套循环问题：如何去除列表项的括号

问题出在你用[drink].transpose()的写法上——[drink]会把原drink列表包裹成一个二维列表，所以each循环里的drinks其实是单元素的子列表（比如[water]），输出自然会带括号。

直接简化循环逻辑，遍历drink原列表即可解决：

def food = ["eggs","chips"]
def drink =["water","juice","cola"]
def meal = []

for (String fd : food){
    // 直接遍历drink列表，拿到单个饮料元素
    drink.each { dr ->
        meal.add("Food: ${fd}, Drinks: ${dr}")
    }
}

pipeline {
    agent any

    stages {
        stage('Results') {
            steps {
                echo 'Results'
                echo "${meal}"
            }
        }
    }
}

运行结果会变成：

Results
[Pipeline] echo
[Food: eggs, Drinks: water, Food: eggs, Drinks: juice, Food: eggs, Drinks: cola, Food: chips, Drinks: water, Food: chips, Drinks: juice, Food: chips, Drinks: cola]
[Pipeline] }

另外，如果你想更贴合Groovy风格，还可以用collectMany简化列表生成，避免手动循环添加元素：

def food = ["eggs","chips"]
def drink =["water","juice","cola"]
def meal = food.collectMany { fd ->
    drink.collect { dr -> "Food: ${fd}, Drinks: ${dr}" }
}

pipeline {
    agent any

    stages {
        stage('Results') {
            steps {
                echo 'Results'
                echo "${meal}"
            }
        }
    }
}

这个写法更简洁，最终效果和手动循环完全一致。

内容的提问来源于stack exchange，提问作者TopTux