無法初始化ArrayListMultimap;由於嵌套？

Question

private ArrayListMultimap<Integer, ArrayList<ArrayList<Point2d>>> detectedAgentPositions; 

上面的代碼不會給我任何錯誤，即一切都整齊地寫入和導入etcetera。但是，當我嘗試初始化detectedAgentPositions像這樣：

private ArrayListMultimap<Integer, ArrayList<ArrayList<Point2d>>> detectedAgentPositions 
     = new ArrayListMultimap<Integer, ArrayList<ArrayList<Point2d>>>(); 

我得到以下錯誤：

no suitable constructor found for ArrayListMultimap(no arguments) constructor ArrayListMultimap.ArrayListMultimap(int,int) is not applicable (actual and formal argument lists differ in length) constructor ArrayListMultimap.ArrayListMultimap(Multimap< ? extends Integer,? extends ArrayList>>) is not applicable (actual and formal argument lists differ in length)

有什麼問題嗎？

Answer 1

如果您ArrayListMultimap類是谷歌共同，它不只是因爲構造函數是私人這樣，你不能叫new ArrayListMultimap<Integer, ArrayList<ArrayList<Point2d>>>()直接簡單地調用ArrayListMultimap.create()而不是爲接下來的工作：

private ArrayListMultimap<Integer, ArrayList<ArrayList<Point2d>>> detectedAgentPositions 
    = ArrayListMultimap.create(); 

Answer 2

更好請使用以下代碼：

Multimap<Integer, ArrayList<ArrayList<Point2d>>> detectedAgentPositions = ArrayListMultimap.create(); 

在這裏閱讀https://google.github.io/guava/releases/19.0/api/docs/com/google/common/collect/ArrayListMultimap.html