问题不在于多维数组，多维数组很好。问题是您不能直接在 class -它需要在方法、构造函数或初始值设定项块中。例如。：

public class PennyPitch {

  int total = 0;
  int[][] board = {{1,1,1,1,1}, {1,2,2,2,1}, {1,2,3,2,1}, {1,2,2,2,1}, {1,1,1,1,1}};
  String[][] boardWithP = {{"1", "1", "1", "1", "1"}, {"1", "2", "2", "2", "1"}, {"1", "2", "3", "2", "1"}, {"1", "2", "2", "2", "1"}, {"1", "1", "1", "1", "1"}};

  public static void main(String[] args) { // Here!
    for(int i = 0; i < 4; i = i + 0){
      int x = (int)(Math.random() * 5);
      int y = (int)(Math.random() * 5);

      if(boardWithP[x][y] != "P"){
        total += board[x][y];
        boardWithP[x][y] = "P";
        i++;
      }
    }
  }
}

另外，作为旁注，您不应该使用 == 或者 != 运算符比较字符串，但使用 equals 方法。查看如何比较java中的字符串？详情。

您需要将代码放入如下方法（函数）中：

public class PennyPitch {
  public static void main(String[] args) {
     int total = 0;
     int[][] board = {{1,1,1,1,1}, {1,2,2,2,1}, {1,2,3,2,1}, {1,2,2,2,1}, {1,1,1,1,1}};
     String[][] boardWithP = {{"1", "1", "1", "1", "1"}, {"1", "2", "2", "2", "1"}, {"1", "2", 
      "3", "2", "1"}, {"1", "2", "2", "2", "1"}, {"1", "1", "1", "1", "1"}};

    for(int i = 0; i < 4; i = i + 0){
       int x = (int)(Math.random() * 5);
       int y = (int)(Math.random() * 5);

       if(boardWithP[x][y] != "P"){
          total += board[x][y];
         boardWithP[x][y] = "P";
         i++;
      }
    }
  } 
}