无法写入和读取保存的游戏文件

Question

我在将游戏数据写入文件和加载文件时遇到问题，这样我就可以从保存数据时的状态恢复游戏。到目前为止，我已经做到了，但它总是抛出一个空指针异常。当我点击saveGame时，我会使用缓冲写入程序来写入所有数据的字符串值。然后，我通过从文件中读取来加载文件，我不知道如何实际显示读取的数据，但在我尝试做到这一点之前，我需要修复空指针异常抛出的问题。我已经尝试过写入文件，我对路径的正确性很有信心，所以我不确定它为什么要这样做。

代码

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.awt.image.*;
public class LifeApplication extends JFrame implements Runnable, MouseListener, MouseMotionListener {
private BufferStrategy strategy;
private Graphics offscreenBuffer;
private boolean gameState[][][]= new boolean[40][40][2];
private int gameStateFrontBuffer = 0;
private boolean isGameRunning = false;
private boolean initialised;
private static LoadSave loadSave;
public LifeApplication()
{
Dimension screensize = java.awt.Toolkit.getDefaultToolkit().getScreenSize();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
int x = screensize.width/2 - 400;
int y = screensize.height/2 - 400;
setBounds(x,y,800,800);
setVisible(true);
this.setTitle("Conway's Game of Life");
createBufferStrategy(2);
strategy = getBufferStrategy();
offscreenBuffer = strategy.getDrawGraphics();
addMouseListener(this);
addMouseMotionListener(this);
for(x = 0; x < 40; x++)
{
for(y = 0; y < 40; y++)
{
gameState[x][y][0] = gameState[x][y][1] = false;
}
}
Thread t = new Thread(this);
t.start();
initialised = true;
}
@Override
public void run()
{
while(true)
{
try{Thread.sleep(100);}
catch(InterruptedException e){
System.out.println("Something happened but dont worry");
}
if(isGameRunning)
applyRules();
this.repaint();
}
}
private void applyRules()
{
int front = gameStateFrontBuffer;
int back = (front +1)%2;
for(int x = 0; x < 40; x++)
{
for(int y = 0; y < 40; y++)
{
int liveneighbours = 0;
for(int xx = -1; xx <= 1; xx++)
{
for(int yy = -1; yy <= 1; yy++)
{
if(xx!=0 || yy!=0)
{
int xxx = x+xx;
if(xxx < 0)
xxx=39;
else if(xxx > 39)
xxx = 0;
int yyy = y + yy;
if(yyy < 0)
yyy=39;
else if (yyy>39)
yyy=0;
if(gameState[xxx][yyy][front])
liveneighbours++;
}
}
}
if(gameState[x][y][front])
{
if(liveneighbours < 2)
gameState[x][y][back] =false;
else if(liveneighbours < 4)
gameState[x][y][back] =true;
else
gameState[x][y][back] =false;
}
else
{
if(liveneighbours == 3)
gameState[x][y][back] =true;
else
gameState[x][y][back] =false;
}
}
}
gameStateFrontBuffer = back;
}
private void randomiseGameState()
{
for(int x = 0; x < 40; x++)
{
for(int y = 0; y < 40; y++)
{
gameState[x][y][gameStateFrontBuffer] = (Math.random()< 0.25);
}
}
}
@Override
public void mouseClicked(MouseEvent m)
{
}
@Override
public void mouseEntered(MouseEvent m)
{
}
@Override
public void mouseExited(MouseEvent m)
{
}
@Override
public void mousePressed(MouseEvent m)
{
if(!isGameRunning)
{
int x = m.getX();
int y = m.getY();
if(x >= 15 && x <= 85 && y >= 40 && y <= 70) {
isGameRunning = true;
return;
}
if(x >= 115 && x <= 215 && y >= 40 && y <= 70) {
randomiseGameState();
return;
}
if(x >= 245 && x <= 315 && y >= 40 && y <= 70){
loadSave.saveGame();
}
if(x >= 345 && x <= 415 && y >= 40 && y <= 70){
loadSave.loadGame();
isGameRunning = true;
}
}
int x = m.getX()/20;
int y = m.getY()/20;
gameState[x][y][gameStateFrontBuffer] = !gameState[x][y][gameStateFrontBuffer];
this.repaint();
}
@Override
public void mouseReleased(MouseEvent m)
{
}
@Override
public void mouseDragged(MouseEvent mouseEvent) {
if(!isGameRunning) {
int x = mouseEvent.getX();
int y = mouseEvent.getY();
try {
if (gameState[x / 20][y / 20][gameStateFrontBuffer]) {
gameState[x / 20][y / 20][gameStateFrontBuffer] = !gameState[x / 20][y / 20][gameStateFrontBuffer];
}
if (!gameState[x / 20][y / 20][gameStateFrontBuffer]) {
gameState[x / 20][y / 20][gameStateFrontBuffer] = true;
}
}
catch(ArrayIndexOutOfBoundsException e){
System.out.println("Cant go there thats out of bounds");
}
}
}
@Override
public void mouseMoved(MouseEvent mouseEvent) {
}
public void paint(Graphics g)
{
if(!initialised)
return;
g = offscreenBuffer;
g.setColor(Color.BLACK);
g.fillRect(0, 0, 800, 800);
g.setColor(Color.GREEN);
g.fillRect(245, 40, 70, 30);
g.setColor(Color.BLACK);
g.drawString("Save", 252, 62);
g.setColor(Color.GREEN);
g.fillRect(345, 40, 70, 30);
g.setColor(Color.BLACK);
g.drawString("Load", 352, 62);

g.setColor(Color.WHITE);
for(int x = 0; x < 40; x++)
{
for(int y = 0; y < 40; y++)
{
if(gameState[x][y][gameStateFrontBuffer])
g.fillRect(x*20, y*20, 20, 20);
}
}
if(!isGameRunning)
{
g.setColor(Color.GREEN);
g.fillRect(15, 40, 70, 30);
g.fillRect(115, 40, 100, 30);
g.setFont(new Font("Times", Font.PLAIN, 24));
g.setColor(Color.BLACK);
g.drawString("Start", 22, 62);
g.drawString("Random", 122, 62);
}
strategy.show();
}
public static void main(String[] args) {
LifeApplication lifeApp = new LifeApplication();
}
}

import java.io.*;
public class LoadSave {
LifeApplication lifeApplication;
public void saveGame() {
String filename = "C:\Users\brads\Desktop\GameOfLife.txt";
try {
BufferedWriter writer = new BufferedWriter(new FileWriter(filename));
writer.write(String.valueOf(lifeApplication));
writer.close();
}
catch (IOException e) {
System.out.println("Cannot write to file");
}
}
public void loadGame() {
String line = null;
String filename = "saveFile.txt";
try {
BufferedReader reader = new BufferedReader(new FileReader(filename));
do {
try {
line = reader.readLine();
} catch (IOException e) {
System.out.println("Cannot read from text file");
}
}
while (line != null);
reader.close();
} catch (IOException e) {
}
}
}

Answer 1

我不认为您正在创建LoadSave实例。

尝试添加以下内容：

public LifeApplication()
{
...
loadSave = new LoadSave();
loadSave.lifeAaplication = this;
....
}