Question

我有一个问题，为什么对字符串数组使用collect不起作用。

这项工作正常

String[][] serversAndQueues = [["server1","queue"],["server1","queue1"],["server2","queue2"]]

serversAndQueues.groupBy { it[ 0 ] }.each { server, value ->
    def queues = []
    value.collect(queues){
        it[1]
    }
    println "$server => $queues"
}

输出

server1 => [queue, queue1]
server2 => [queue2]

但如果我尝试将队列定义为字符串数组 def queues = [] as String [] ，则会抛出异常

String[][] serversAndQueues = [["server1","queue"],["server1","queue1"],["server2","queue2"]]

serversAndQueues.groupBy { it[ 0 ] }.each { server, value ->
    def queues = [] as String[]
    value.collect(queues){
        it[1]
    }
    println "$server => $queues"
}

输出

Exception thrown

    groovy.lang.MissingMethodException: No signature of method: java.util.ArrayList.collect() is applicable for argument types: ([Ljava.lang.String;, ConsoleScript40$_run_closure2_closure3) values: [[], ConsoleScript40$_run_closure2_closure3@ff8c2a]
    Possible solutions: collect(), collect(), collect(groovy.lang.Closure), collect(java.util.Collection, groovy.lang.Closure), collect(java.util.Collection, groovy.lang.Closure), collect(groovy.lang.Closure)

        at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.unwrap(ScriptBytecodeAdapter.java:55)

        at org.codehaus.groovy.runtime.callsite.PojoMetaClassSite.call(PojoMetaClassSite.java:46)
    ..
    ...

Answer 1

您无法收集数组，只能收集集合

你可以尝试

def queues = value.collect { it[ 1 ] } as String[]

收集可能def queues = [] as String []？

1 个答案: