想要多维数组，但获得空指针异常 [英] Want a multidimensional array but get a null pointer exception

问题描述

  1 public class TestWin{
  2     public static void main(String[] args){
  3         int n;
  4         hexagon[][] board;
  5
  6         n = 4;
  7         board = new hexagon[n][n];
  8         board[0][0].value = 'R';

嗨.javac不喜欢我在第8行上所做的事情.有人知道为什么吗?

Hi. javac doesn't like what I did on line 8. Does anyone know why?

推荐答案

kwatford上的现货.您在第7行所做的只是告诉Java在二维数组中为n * n个Hexagon对象创建空间.

Spot on kwatford. All you have done with line 7 is to tell java to create space for n*n Hexagon objects in a 2 dimensional array.

您仍然需要为每个这些六边形调用新的

You will still need to call new for each of these Hexagons

本质上，您需要将第7行替换为以下内容:

Essentially, you need to replace line 7 with something like:

board = new Hexagon[n][n];
for(int i=0; i<n; i++)
    for(int j=0; j<n; j++)
        board[i][j] = new Hexagon();

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