Question

我开始学习groovy，因为我喜欢通过练习学习，所以我写了那个小应用程序：

def height = 1; def commands; def floors; def finished = false

def up = { height < 5 ? height++ : println("Can't go higher!") }
def down = { height > -1 ? height-- : println("Can't go lower!") }
def help = { 
    print "Commands are " 
    commands.each{key, val -> print "'$key' "}
    println() 
}
def printFloors = {
    println "Floors are "
    floors.each{key,val -> println "'$key' -> '$val'"}
    println()
}
def exit = { finished = true }
def prompt = { print floors["$height"] }

commands = [ 'u': up, 
             'up': up,
             'd': down,
             'down': down,
             'help': help,
             '': help,
             'exit': exit,
             'pf': printFloors]

floors = [ "-1": "Basement : " ,
           "0": "Ground : " ,
           "5": "Penthouse : " ]
(1..4).each{floors += ["${it}" : "Floor ${it} : " ] }

bR = new BufferedReader(new InputStreamReader(System.in))

while(!finished){
    prompt()
    def cmd = bR.readLine()
    def code = commands[cmd]
    if(code != null){
        code()
    }
}

除了打印你所在的楼层（提示功能）外，一切正常。如果你在地下室，底层或顶层公寓，它会打印，但不会选择“Floor i：”并打印null而不是：/ 当我输入“pf”打印我的楼层词典时，值就在那里...... 有任何想法吗？感谢

Answer 1

您正在将GString个实例添加为地图中的关键字，然后使用String个实例进行搜索。

两者不一样（尽管外观相同 - 请参阅“GStrings不是字符串”部分on this page）

尝试更改：

(1..4).each{floors += ["${it}" : "Floor ${it} : " ] }

到

(1..4).each{floors += [ ("${it}".toString()): "Floor ${it} : " ] }

为什么groovy在字典中看不到某些值？

1 个答案: