感谢您花时间阅读我的问题。我目前在开发一个基于文本的小型冒险游戏时遇到问题。现在我在更新地图时收到此错误消息:
Exception in thread "main" java.lang.NullPointerException
at main.GameManager.update(GameManager.java:92)
at main.GameManager.run(GameManager.java:78)
at main.Main.main(Main.java:8)
我有一个关于为什么会发生这种情况的理论,因为我花了几个小时试图自己解决这个问题。我的理论是地图生成器正在创建一个具有空值的正方形,这导致更新方法遇到错误。我注意到的另一件事是每次随机对象都会出现错误消息。有时,实体返回错误消息,而其他时候武器返回错误消息。更新方法的代码如下:
注意:我在错误消息返回错误的代码行上放了两个星号
//method executed every loop until end
private void update(Object[][] gameMap, GUIController guiController){
player.update(gameMap, guiController);
//updates every object on the map besides player
for(int row = 0; row<mapManager.getWIDTH(); row++){
for(int col = 0; col<mapManager.getHEIGHT(); col++){
//if the square has something inside of it
if(!(gameMap[row][col] instanceof EmptySquare)){
**gameMap[row][col].update(gameMap, guiController);
}
}
}
//check
guiController.displayMessage("updated");
}
地图生成代码如下:
for(int row = 0; row < WIDTH; row++){
for(int col = 0; col < HEIGHT; col++){
Random r = new Random();
//NOTE: +1 included to get number 1-6 instead of 0-6 or 0-5
int rand = r.nextInt(6) + 1;
int rand2 = r.nextInt(2) + 1;
System.out.println(rand);
System.out.println(rand2);
if(rand <= 2){
//an empty tile
gameMap[row][col] = new EmptySquare("Empty Square", 0);
gameMap[row][col].setLocation(row, col);
}else if(rand == 3 || rand == 4){
//monster tile
//decides what monster to put in the tile base on level
if(row <= 2 && col <= 2){
switch(rand2){
case 1: gameMap[row][col] = new Entity("Snake", 1, row, col, 5, Weapon.weaponList[0]);
break;
case 2: gameMap[row][col] = new Entity("Flesh Eating Caterpillar", 1, row, col, 7, Weapon.weaponList[0]);
break;
}
}else if((row > 2 && col > 2) && (row <= 5 && col <=5)){
switch(rand2){
case 1: gameMap[row][col] = new Entity("Spider", 2, row, col, 12, Weapon.weaponList[1]);
break;
case 2: gameMap[row][col] = new Entity("Zombie", 2, row, col, 20, Weapon.weaponList[1]);
break;
}
}else if((row > 5 && col > 5) && (row <= 8 && col <= 8)){
switch(rand2){
case 1: gameMap[row][col] = new Entity("Giant", 3, row, col, 30, Weapon.weaponList[2]);
break;
case 2: gameMap[row][col] = new Entity("Fire Drake", 3, row, col, 40, Weapon.weaponList[3]);
break;
}
}
}else if(rand >= 5){
//weapon tile
//decides which monster to put int he tile based on level
if(row <= 2 && col <= 2){
switch(rand2){
case 1: gameMap[row][col] = new Weapon("Wood Sword", 1, row, col, Material.WOOD);
break;
case 2: gameMap[row][col] = new Weapon("Bronze Sword", 1, row, col, Material.BRONZE);
break;
}
}else if((row > 2 && col > 2) && (row <= 5 && col <=5)){
switch(rand2){
case 1: gameMap[row][col] = new Weapon("Steel Sword", 2, row, col, Material.STEEL);
break;
case 2: gameMap[row][col] = new Weapon("Refined Steel Sword", 2, row, col, Material.REFINEDSTEEL);
break;
}
}else if((row > 5 && col > 5) && (row <= 8 && col <= 8)){
switch(rand2){
case 1: gameMap[row][col] = new Weapon("Gold Sword", 3, row, col, Material.GOLD);
break;
case 2: gameMap[row][col] = new Weapon("Emerald Sword", 3, row, col, Material.EMERALD);
break;
}
}
}
}
}
感谢任何帮助,因为我已经为此工作了几个小时,但没有成功。如果您需要更多代码,对代码有任何疑问,或者对此有任何疑问,请询问。我的第一个目标是找出这个错误,了解哪里出了问题,并了解可以采取哪些措施来防止它再次发生。
谢谢