java - 定义多维数组列表的容量

Question

我创建了一个名为 Grid 的类，并且正在努力定义嵌套 ArrayList 的容量。这是我目前拥有的:

public class Grid extends GameObject {

   private int cols;
   private int rows;
   private int colWidth;
   private int rowHeight;
   private ArrayList<ArrayList<GameObject>> contents;

   public Grid(int x, int y, int cols, int rows, int colWidth, int rowHeight, ID id) {
       super();
       this.x = x;
       this.y = y;
       this.cols = cols;
       this.rows = rows;
       this.colWidth = colWidth;
       this.rowHeight = rowHeight;

       //Here I want to define the contents

       this.width = colWidth * cols;
       this.height = rowHeight * rows;
       this.id = id;
   }
 }

代码应如下所示:

this.contents = new ArrayList<ArrayList<GameObject>(cols)>(rows);

但这会产生错误。有谁知道如何解决这个问题，我将不胜感激!提前致谢!

Answer 1

您无法使用单个初始化语句来完成此操作。您需要一个循环。

this.contents = new ArrayList<ArrayList<GameObject>>(rows); // this creates an empty 
                                                            // ArrayList
for (int i = 0; i < rows; i++) { // this populates the ArrayList with rows empty ArrayLists
    this.contents.add(new ArrayList<GameObject>(cols));
    // and possibly add another loop to populate the inner array lists
}