尝试运行此程序时出现错误。这不是整个程序,只是我认为问题出在哪里的几个细节。错误指出线程“main”中的异常java.lang.NullPointerException?这是什么意思?
if(board[randSpace].isEmpty()) and
cl.makeChutes(5);"
错误是:
"Exception in thread "main" java.lang.NullPointerException
at ChutesAndLadders.makeChutes(ChutesAndLadders.java:29)
at ChutesAndLadders.main(ChutesAndLadders.java:67)"
这是我的计划:
import java.util.Random;
public class ChutesAndLadders{
Cell [] board = new Cell [100];
Random rand = new Random();
public int chutes, ladders;
public void makeChutes (int a){
int makeChutes = a;
for (int i = 0; i < a; i++){
int randSpace = rand.nextInt(99);
if(board[randSpace].isEmpty())
board[randSpace] = new Cell (-10,"C");
else
i--;
}
}
public static void main(String[] args) {
// Create an instance of ChutesAndLadders
ChutesAndLadders cl = new ChutesAndLadders(10,10);
// Randomly place 5 more chutes and 5 more ladders
cl.makeChutes(5);
cl.makeLadders(5);
这里是我的isEmpty: 公共布尔的isEmpty(){ 为(INT I = 0; i < board.length; i ++) if(board [i] .isEmpty()) 返回true; } return false; }
我的编码可能完全错误。我仍然在学习,所以请耐心等待。谢谢!