在Groovy中循环Map？

Question

I have a very simple task I am trying to do in Groovy but cannot seem to get it to work. I am just trying to loop through a map object in groovy and print out the key and value but this code does not work.

// A simple map
def map = [
        iPhone : 'iWebOS',
        Android: '2.3.3',
        Nokia  : 'Symbian',
        Windows: 'WM8'
]

// Print the values
for (s in map) {
    println s + ": " + map[s]
}

I am trying to get the output to look like this:

iPhone: iWebOS
Android: 2.3.3
Nokia: Symbian
Windows: WM8

Could someone please elaborate on how to do this??

Answer 1

Quite simple with a closure:

def map = [
           'iPhone':'iWebOS',
           'Android':'2.3.3',
           'Nokia':'Symbian',
           'Windows':'WM8'
           ]

map.each{ k, v -> println "${k}:${v}" }

Answer 2

Alternatively you could use a for loop as shown in the Groovy Docs :

def map = ['a':1, 'b':2, 'c':3]
for ( e in map ) {
    print "key = ${e.key}, value = ${e.value}"
}

/*
Result:
key = a, value = 1
key = b, value = 2
key = c, value = 3
*/

One benefit of using a for loop as opposed to an each closure is easier debugging, as you cannot hit a break point inside an each closure (when using Netbeans).

Answer 3

When using the for loop, the value of s is a Map.Entry element, meaning that you can get the key from s.key and the value from s.value

Answer 4

Another option:

def map = ['a':1, 'b':2, 'c':3]
map.each{
  println it.key +" "+ it.value
}