我正在尝试编写战舰游戏，但运行时出现奇怪的错误:线程“main”中出现异常 java.lang.NullPointerException 在Caculations.findShip(Caculations.java:29) 在 Board.main(Board.java:60)
请帮助我，我被困住了，我不知道如何继续!这是我的代码:(注意，它在我的 Eclipse 工作环境中的 2 个类文件中)
public class Board {
public static void main(String[] args) {
boolean continuePlay = true;
int[][] board = new int[10][10]; // creating 2d array 'board'
char[][] boardGraphical = new char[10][10]; // creating 2d array 'board
// this time the visual
for (int x = 0; x < 10; x++) { // for within for //initializing elements
// in both boards using double for
// method
for (int y = 0; y < 10; y++) {
board[x][y] = 0;
boardGraphical[x][y] = 'o';
System.out.println("Board element " + x + " " + y // printing
// initialized
// elements
// here
+ " initialized");
}
}
/*
* 1) Make user ships 1 and computer ships 2 (all numbers other than 0 =
* true)
*
* 2) Make it where if the computer gets a hit on a '1' than it sets
* that value to like a 3 or something so it knows when the ship is
* sunk. So in a if it does if([x][y] && [x][y])
* System.out.println("You sunk my ship!");
*
* 3) REMEMBER YOU CAN DO MULTIPLE IFS INSIDE IFS FOR MULTIPLE
* CONDITIONS. 4) declare ships here!
*
* 5) PUT STUFF IN A WHILE LOOP SO COMP CAN KEEP GOING
*/
board[3][3] = 1; // declaring a battleship. Very important.
board[3][4] = 1;
board[3][5] = 1;
boardGraphical[3][3] = 's';
boardGraphical[3][4] = 's';
boardGraphical[3][5] = 's';
while (continuePlay == true) { // while loop so that computer keeps
// guessing
// WITHIN THIS LOOP KEEP REPRINTING THE BOARD
double computerChoiceXd = Math.floor(Math.random() * 10); // using
// Math.random
// functions
// for
// computers
// first
// guess
// to be
// a
// random
// num
double computerChoiceYd = Math.floor(Math.random() * 10);
int computerChoiceX = (int) computerChoiceXd;
int computerChoiceY = (int) computerChoiceYd;
if (board[computerChoiceX][computerChoiceY] == 1) { // checking if
// math.random
// landed on a
// ship point
System.out.println("Computer got a hit at " + computerChoiceX
+ " " + computerChoiceY);
board[computerChoiceX][computerChoiceY] = 2; // setting the
// point as 2 or
// 'hit'
boardGraphical[computerChoiceX][computerChoiceY] = 'H';
for (int row = 0; row < 10; row++) { // printing out graphical
// board using the same
// method as when
// intializing
for (int col = 0; col < 10; col++) {
System.out.print(boardGraphical[row][col]);
}
System.out.println(" "); // spacer for printing
}
Caculations test = new Caculations(computerChoiceX, // Creating
// a new
// object of
// calculation
computerChoiceY, board);
test.findShip();
// break;
if (board[3][3] == 2) { // checking to see if ship is sunk using
// a triple if statement
if (board[3][4] == 2) {
if (board[3][5] == 2) {
System.out.println("Battleship sunk!");
continuePlay = false; // if so than it breaks out of
// loop to end the game
break;
}
}
}
} else if (board[computerChoiceX][computerChoiceY] == 0) { // otherwise
// if
// the
// area
// is a
// 0 or
// 'unmarked'
System.out.println("Computer missed at " + computerChoiceX
+ " " + computerChoiceY);
boardGraphical[computerChoiceX][computerChoiceY] = 'x'; // mark
// area
// as a
// miss
for (int row = 0; row < 10; row++) { // print out board
for (int col = 0; col < 10; col++) {
System.out.print(boardGraphical[row][col]);
}
System.out.println(" ");
}
}
}
}
}
public class Caculations {
int xValue;
int yValue;
int[][] myArray;
int[][] storage = new int[10][10];
boolean xAxisChangeP;
boolean yAxisChangeP;
boolean xAxisChangeN;
boolean yAxisChangeN;
boolean notSunk;
Caculations(int x, int y, int[][] myArray) {
xValue = x;
yValue = y;
xAxisChangeP = true;
yAxisChangeP = true;
xAxisChangeN = true;
yAxisChangeN = true;
notSunk = true;
}
void findShip() {
while (notSunk == true) {
// 1
while (xAxisChangeP == true) {
if (myArray[xValue + 1][yValue] == 1) {
myArray[xValue + 1][yValue] = 2;
if (myArray[3][3] == 2) {
if (myArray[3][4] == 2) {
if (myArray[3][5] == 2) {
System.out.println("Battleship sunk!");
notSunk = false;
}
}
}
continue;
}
else {
xAxisChangeP = false;
}
}
while (xAxisChangeN == true) {
if (myArray[xValue - 1][yValue] == 1) {
myArray[xValue - 1][yValue] = 2;
if (myArray[3][3] == 2) {
if (myArray[3][4] == 2) {
if (myArray[3][5] == 2) {
System.out.println("Battleship sunk!");
notSunk = false;
}
}
}
continue;
}
else {
xAxisChangeN = false;
}
}
// 1
while (yAxisChangeP == true) {
if (myArray[xValue][yValue + 1] == 1) {
myArray[xValue][yValue + 1] = 2;
if (myArray[3][3] == 2) {
if (myArray[3][4] == 2) {
if (myArray[3][5] == 2) {
System.out.println("Battleship sunk!");
notSunk = false;
}
}
}
continue;
}
else {
yAxisChangeP = false;
}
}
while (yAxisChangeN == true) {
if (myArray[xValue][yValue - 1] == 1) {
myArray[xValue][yValue - 1] = 2;
if (myArray[3][3] == 2) {
if (myArray[3][4] == 2) {
if (myArray[3][5] == 2) {
System.out.println("Battleship sunk!");
notSunk = false;
}
}
}
continue;
}
else {
yAxisChangeN = false;
}
}
}
}
}
最佳答案
你初始化了myarray吗？最好是调试代码以查看哪个语句引发异常。在 Eclipse 中，您可以添加 NullPointerExeption 作为断点并进行调试。
关于java - 为什么我在战舰游戏中收到错误 java.lang.NullPointerException？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/27141455/