if
println false ? 1 : 2 // 2
println false ?: 2 // 2
println true ?: 2 // true
？
dictionary – groovy: safely find a key in a map and return its value – Stack Overflow
def mymap = [name:"Gromit", id:1234]
def x = mymap.find{ it.key == "likes" }?.value
if(x)
println "x value: ${x}"
println x.getClass().name
?. checks for null and does not create an exception in Groovy. If the key does not exist, the result will be a org.codehaus.groovy.runtime.NullObject.
Switch
// 将 Gitee 的团队名转化到对应的 k8s 的命名空间
// 因为团队名不符合规范，所以加个转换层，映射到 k8s 命名空间
def giteeTeamToK8sNamespace(String giteeTeamName) {
def returnVal = 'default'
switch (giteeTeamName) {
case 'KaiFa':
returnVal = 'df-common'
break
case 'YunWei':
returnVal = 'df-om'
break
}
return returnVal
}
循环 | Loop
使用 each 方法
listFoo.each { item ->
// do some stuff
}
使用 find 方法
Can you break from a Groovy “each” closure?
当使用 find 遍历时，在 Cloure 中返回 true 将停止遍历：
def a = [1, 2, 3, 4, 5, 6, 7]
a.find {
if (it > 5)
return true // break
println it // do the stuff that you wanted to before break
return false // keep looping
}
// 该程序将输出 1, 2, 3, 4, 5
也可以通过元编程实现自己的 find 函数：
List.metaClass.eachUntilGreaterThanFive = { closure ->
for ( value in delegate ) {
if ( value > 5 ) break
closure(value)
}
}
def a = [1, 2, 3, 4, 5, 6, 7]
a.eachUntilGreaterThanFive {
println it
}