按地圖對地圖內的地圖進行排序

Question

我正在嘗試對Groovy中具有地圖值的地圖進行排序。我想迭代地圖並打印出按lastName和firstName值排序的值。因此，在下面的例子：

def m = 
[1:[firstName:'John', lastName:'Smith', email:'john@john.com'], 
2:[firstName:'Amy', lastName:'Madigan', email:'amy@amy.com'], 
3:[firstName:'Lucy', lastName:'B',  email:'lucy@lucy.com'], 
4:[firstName:'Ella', lastName:'B',  email:'ella@ella.com'], 
5:[firstName:'Pete', lastName:'Dog', email:'pete@dog.com']] 

所期望的結果將是：

[firstName:'Ella', lastName:'B',  email:'ella@ella.com'] 
[firstName:'Lucy', lastName:'B',  email:'lucy@lucy.com'] 
[firstName:'Pete', lastName:'Dog', email:'pete@dog.com'] 
[firstName:'Amy', lastName:'Madigan', email:'amy@amy.com'] 
[firstName:'John', lastName:'Smith', email:'john@john.com'] 

我已經試過m.sort {it.value.lastName & & it.value.firstName}和M。排序{[it.value.lastName，it.value.firstName]}。通過m.sort {it.value.lastName}進行排序可行，但不會按firstName排序。

有人可以幫忙，非常感謝，謝謝！

Answer 1

這應做到：

m.values().sort { a, b -> 
    a.lastName <=> b.lastName ?: a.firstName <=> b.firstName 
}