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在我的Boss類中，它表示我的List「bulletlist」爲空，並給我一個運行時錯誤，但是我沒有看到錯誤，有人能告訴我我做錯了什麼嗎？如果我不更新我的老闆班，遊戲運行良好。我把我的主要課程，玩家課程和子彈課也放入其中。如何在我的類中調試意外的null來自哪裏？
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Media;
namespace Space_Shooter
{
public class Boss
{
public Texture2D texture, bulletTexture , healthBarTexture;
public Vector2 position;
public float randomPositionX, randomPositionY , bulletDamage, shipDamage , health , MaxBullets;
public int speed, bulletSpeed , bulletDelayTime, bulletDelayTimeReset;
public bool isVisible;
public Rectangle boundingBox , bossHealthBar;
public List<Bullet> bulletList;
Random random = new Random();
Player p = new Player();
public Boss(Texture2D newTexture, Vector2 newPosition, Texture2D newBulletTexture)
{
texture = newTexture;
position = newPosition;
bulletTexture = newBulletTexture;
bulletList = new List<Bullet>();
bulletSpeed = 25;
bulletDamage = 25;
shipDamage = p.health/2;
health = 2000;
bulletDelayTime = 30;
bulletDelayTimeReset = 30;
MaxBullets = 30;
isVisible = true;
}
public Boss()
{
}
public void Draw(SpriteBatch spriteBatch)
{
spriteBatch.Draw(texture, position, Color.White);
spriteBatch.Draw(healthBarTexture, bossHealthBar, Color.White);
foreach (Bullet b in bulletList)
{
b.Draw(spriteBatch);
}
}
public void loadContent(ContentManager content)
{
texture = content.Load<Texture2D>("Ship4");
bulletTexture = content.Load<Texture2D>("EnemyBullet");
healthBarTexture = content.Load <Texture2D> ("healthbar");
}
public void update(GameTime gameTime)
{
updateBullets();
Shoot();
checkBossCollison();
// Making bosses health bar
bossHealthBar = new Rectangle((int)position.X, (int)position.Y + 30, (int)health, 25);
// Creating collision box for boss
boundingBox = new Rectangle((int)position.X, (int)position.Y, (int)texture.Width, (int)texture.Height);
randomPositionX = random.Next(50, 750);
randomPositionY = random.Next(50, 400);
// setting boss movement
if (position.Y > randomPositionY)
position.Y -= speed;
if (position.Y < randomPositionY)
position.Y += speed;
if (position.X > randomPositionX)
position.X -= speed;
if (position.X < randomPositionX)
position.X += speed;
}
public void updateBullets()
{
// for each bullet in the bulletList: update the movement and if the bullet hits the bottom of the screen, remove it from the list
foreach (Bullet b in bulletList)
{
//make a Bounding box for every bullet in the bulletList
b.boundingBox = new Rectangle((int)b.position.X, (int)b.position.Y, b.texture.Width, b.texture.Height);
// set movement for the bullets
// if a bullet hits the bottom of the screen, then make visable false
if (b.position.Y >= 850)
b.isVisible = false;
// go through the bulletList and see if any of the bullets are not visible, if they are not then remove that bullet from the bulletList
for (int i = 0; i < bulletList.Count; i++)
{
if (!bulletList[i].isVisible)
{
bulletList.RemoveAt(i);
i--;
}
}
}
}
public void checkBossCollison()
{
// if boss ship comes in bcontact with player ship player is damaged
if (boundingBox.Intersects(p.boundingBox))
p.health -= shipDamage;
// if player bullets hit boss then boss is damaged and player bullets go invisible
for(int i = 0; i < p.bulletList.Count; i++)
{
if (boundingBox.Intersects(p.bulletList[i].boundingBox))
{
health -= p.bulletDamage;
p.bulletList[i].isVisible = false;
if (health == 0)
isVisible = false;
}
}
// if boss shoots player player is damaged and boss bullets go invisible
for(int i = 0; i < bulletList.Count; i++)
{
if (p.boundingBox.Intersects(bulletList[i].boundingBox))
{
p.health -= bulletDamage;
bulletList[i].isVisible = false;
}
}
}
public void Shoot()
{
// shoot only if our bullet delay resets
if (bulletDelayTime >= 0)
bulletDelayTime--;
// If bulletDelay is at 0, create a new bullet at enemy position, make it visible on the screen, then add that bullet to bulletList
if (bulletDelayTime <= 0)
{
// create new bullet and center it front and center of enemy ship
Bullet newBullet = new Bullet(bulletTexture);
newBullet.position = new Vector2(position.X + texture.Width/2 - newBullet.texture.Width/2, position.Y + 30);
newBullet.isVisible = true;
if (bulletList.Count() < MaxBullets)
bulletList.Add(newBullet);
}
// Reset bullet delay
if (bulletDelayTime == 0)
bulletDelayTime = bulletDelayTimeReset;
}
}
}
using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Media;
namespace Space_Shooter
{
// Main
public class Game1 : Microsoft.Xna.Framework.Game
{
GraphicsDeviceManager graphics;
// variabls
SpriteBatch spriteBatch;
Random random = new Random();
Random randomNumberOfAsteroids = new Random();
int maxNumberOfAsteroids;
int numbersOfInvisibleEnemies;
// Lists
List<Asteroid> asteroidList = new List<Asteroid>();
List<Enemy> enemyList = new List<Enemy>();
// making player and starfield objects
Player P = new Player();
StarField starfield = new StarField();
Enemy E = new Enemy();
Boss boss = new Boss();
// Construtor
public Game1()
{
graphics = new GraphicsDeviceManager(this);
// setting full scren to off and setting screen measurments
graphics.IsFullScreen = false;
graphics.PreferredBackBufferWidth = 800;
graphics.PreferredBackBufferHeight = 850;
maxNumberOfAsteroids = 5; // Set the max number of asteroids that will be on the screen at one time (randomly 0 to Max number)
numbersOfInvisibleEnemies = 0;
// Setting Title of screen
this.Window.Title = "Star Voyage";
Content.RootDirectory = "Content";
}
// Initialize
protected override void Initialize()
{
base.Initialize();
}
// Load content
protected override void LoadContent()
{
// Create a new SpriteBatch, which can be used to draw textures.
spriteBatch = new SpriteBatch(GraphicsDevice);
// Call Load content function from Player.cs
P.LoadContent(Content);
starfield.LoadContent(Content);
boss.loadContent(Content);
}
// unload content
protected override void UnloadContent()
{
}
// update game screen
protected override void Update(GameTime gameTime)
{
// updating enemies and checking collision of thier ships to player ship
foreach (Enemy e in enemyList)
{
if (e.boundingBox.Intersects(P.boundingBox))
{
P.health -= e.enemyShipDamage;
e.isVisible = false;
}
// check enemy bullet collision with player ship
for (int i = 0; i < e.bulletList.Count; i++)
{
if (P.boundingBox.Intersects(e.bulletList[i].boundingBox))
{
P.health -= e.enemyBulletDamage;
e.bulletList[i].isVisible = false;
}
}
// check player bullet collision with enemy ships
for (int i = 0; i < P.bulletList.Count; i++)
{
if (e.boundingBox.Intersects(P.bulletList[i].boundingBox))
{
// when bullet hits enemy ship they disapear
P.bulletList[i].isVisible = false;
e.health -= P.bulletDamage;
if (e.health == 0)
e.isVisible = false;
}
}
e.Update(gameTime);
}
// for each asteroid in the asteroid list call the update function from Asteroid.cs
foreach (Asteroid a in asteroidList)
{
//Check to see if any of the arteroids are colliding with player ship
if (a.boundingBox.Intersects(P.boundingBox))
{
P.health -= a.asteroidDamage; // taking 20 off of player health bar each time the play shit is hit by an asteroid
a.isVisible = false;
}
// going through bullet list to see if any bullets come in contact with asteroids if they do set both the bullet and the asteroid to not visible
for (int i = 0; i < P.bulletList.Count; i++)
{
if (a.boundingBox.Intersects(P.bulletList[i].boundingBox))
{
a.isVisible = false;
P.bulletList.ElementAt(i).isVisible = false;
}
}
a.Update(gameTime);
}
loadAsteroids();
loadEnemyShips();
// Call fucntion Update from Player,cs
P.Update(gameTime);
// Call function update from StarField.cs
starfield.Update(gameTime);
boss.update(gameTime);
// Allows the game to exit
if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
this.Exit();
base.Update(gameTime);
}
// Draw to game screen
protected override void Draw(GameTime gameTime)
{
spriteBatch.Begin();
starfield.Draw(spriteBatch);
foreach (Asteroid a in asteroidList)
{
a.Draw(spriteBatch);
}
foreach (Enemy e in enemyList)
{
e.Draw(spriteBatch);
}
// Backgound color
GraphicsDevice.Clear(Color.CornflowerBlue);
// Call Draw fuction from Player.cs
P.Draw(spriteBatch);
// boss.Draw(spriteBatch);
spriteBatch.End();
base.Draw(gameTime);
}
// Load Asteroids function
public void loadAsteroids()
{
// creating random variabls for X and Y positions of asteroids
int random_x = random.Next(0, 750), random_y = random.Next(-600, -50);
// if the number of Asteroids on the screen is less than the variable (numberOfAsteroids), create more untill it is not
if (asteroidList.Count() < randomNumberOfAsteroids.Next(0, maxNumberOfAsteroids))
{
asteroidList.Add(new Asteroid(Content.Load<Texture2D>("asteroid"), new Vector2(random_x, random_y)));
}
// if any of the asteroids from the list are destroyed (not visible) then remove them from the list
for (int i = 0; i < asteroidList.Count; i++)
{
if (!asteroidList[i].isVisible)
{
asteroidList.RemoveAt(i);
i--;
}
}
}
public void loadEnemyShips()
{
// creating random variabls for X and Y positions of asteroids
int random_x = random.Next(0, 750), random_y = random.Next(-600, -50);
// if the number of enemies on the screen is less than the variable (numberOfEnemies), create more untill it is not
if (enemyList.Count() < 3 && numbersOfInvisibleEnemies <= 9)
{
enemyList.Add(new Enemy(Content.Load<Texture2D>("enemyship"), new Vector2(random_x, random_y), Content.Load<Texture2D>("EnemyBullet")));
}
// keeping count of the number of destroied enemies
for (int i = 0; i < enemyList.Count; i++)
{
if (!enemyList[i].isVisible)
numbersOfInvisibleEnemies += 1;
// if any of the enemies from the list are destroyed (not visible) or if they go passed the bottom of the screen, then remove them from the list
if (!enemyList[i].isVisible || enemyList[i].position.Y >= 840)
{
enemyList.RemoveAt(i);
--i;
}
}
}
}
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Media;
namespace Space_Shooter
{
// main
public class Player
{
// Variables
public Texture2D texture , bulletTexture , healthTexture;
public Vector2 position , healthBarPosition;
public int speed;
public float health , bulletDamage , bulletDelay , bulletDelayReset;
double bulletCount;
// Lists
public List<Bullet> bulletList;
// Collision variables
public bool isColliding;
public Rectangle boundingBox , healthRectangle;
// Constructor
public Player()
{
bulletList = new List<Bullet>();
bulletDelay = 1; // for faster fire rate reduce number
bulletDelayReset = 5; // bullet delay reset has to be the same number as bullet delay
bulletCount = 1000; // amount of bullets alowed on the screen at a time
texture = null;
health = 200;
bulletDamage = 3;
healthBarPosition = new Vector2(50, 50);
position = new Vector2 (300, 300) ;
speed = 10;
isColliding = false;
}
// Load content
public void LoadContent(ContentManager Content)
{
texture = Content.Load<Texture2D>("player01");
bulletTexture = Content.Load<Texture2D>("playerbullet");
healthTexture = Content.Load<Texture2D>("healthbar");
}
// Draw
public void Draw(SpriteBatch spritebatch)
{
spritebatch.Draw(texture, position, Color.White);
spritebatch.Draw(healthTexture, healthRectangle, Color.White);
// For each Bullet b (bullet) in our bullet list, draw the bullet
foreach (Bullet b in bulletList)
{
b.Draw(spritebatch);
}
}
// Update
public void Update(GameTime gametime)
{
// Checking for keyboard input every frame
KeyboardState keystate = Keyboard.GetState();
// setting collision box for player ship
boundingBox = new Rectangle((int)position.X, (int)position.Y, texture.Width, texture.Height);
//set rectangle for healthbar (where to print on the screen and the height and width (25) is height (health is width
healthRectangle = new Rectangle((int) healthBarPosition.X, (int) healthBarPosition.Y, (int)health, 25);
if (keystate.IsKeyDown(Keys.Space))
{
shoot();
}
updateBullets();
// ship controls
if (keystate.IsKeyDown(Keys.W))
position.Y = position.Y - speed;
if (keystate.IsKeyDown(Keys.S))
position.Y = position.Y + speed;
if (keystate.IsKeyDown(Keys.A))
position.X = position.X - speed;
if (keystate.IsKeyDown(Keys.D))
position.X = position.X + speed;
// Keep ship in screen bounds
if (position.X <= 0)
position.X = 0;
if (position.X >= 800 - texture.Width)
position.X = 800 - texture.Width;
if (position.Y <= 0)
position.Y = 0;
if (position.Y >= 850 - texture.Height)
position.Y = 850 - texture.Height;
}
// Shoot Function, used to set the starting position of the players bullet
public void shoot()
{
// Shoot only if the bullet delay resets
if (bulletDelay >= 0)
bulletDelay--;
// If bulletDelay is at 0, create a new bullet at player position, make it visible on the scrren, then add that bullet to bulletList
if (bulletDelay <= 0)
{
Bullet newBullet1 = new Bullet(bulletTexture);
newBullet1.position = new Vector2(position.X - newBullet1.texture.Width/2, position.Y + 30);
newBullet1.isVisible = true;
Bullet newBullet2 = new Bullet(bulletTexture);
newBullet2.position = new Vector2(position.X + 64 - newBullet2.texture.Width/2, position.Y + 30);
newBullet2.isVisible = true;
// control the amount of bullets on the screen by increasing number
if (bulletList.Count() < bulletCount)
bulletList.Add(newBullet1);
bulletList.Add(newBullet2);
}
// Reset bullet dleay
if (bulletDelay == 0)
bulletDelay = bulletDelayReset;
}
public void updateBullets()
{
// for each bullet in the bulletList: update the movement and if the bullet hits the top of the screen, remove it from the list
foreach (Bullet b in bulletList)
{
// set movement for the bullets
b.position.Y = b.position.Y - b.speed;
//make a Bounding box for every bullet in the bullet list
b.boundingBox = new Rectangle((int)b.position.X, (int)b.position.Y, b.texture.Width, b.texture.Height);
// if a bullet hits the top of the screen, then make visable false
if (b.position.Y <= 0)
b.isVisible = false;
}
// go through the bulletList and see if any of the bullets are not visible, if they are not then remove that bullet from the bulletList
for (int i = 0; i < bulletList.Count; i++)
{
if (!bulletList[i].isVisible)
{
bulletList.RemoveAt(i);
i--;
}
}
}
}
}
using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Media;
namespace Space_Shooter
{
public class Bullet
{
public Rectangle boundingBox;
public Texture2D texture;
public Vector2 position , origin;
public float speed;
public bool isVisible;
public Bullet(Texture2D newTexture)
{
speed = 25;
texture = newTexture;
isVisible = false;
}
public void Draw(SpriteBatch spritebatch)
{
spritebatch.Draw(texture, position, Color.White);
}
}
}
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