“嗨,阿米戈!”
“你好!”
“你如何称呼高级军官?”
“对不起,先生。”
“你好,松鼠船长,先生。”
“这样更好。”
“你今天有新的秘密任务。”
“你需要写一个太空战斗模拟。”
“酷!呃……我是说,我准备好了,长官。”
“正好,我有了个主意,这个如何?”
“不行,太难了。”
“我们将从更简单的事情开始:”
“唔...”
“什么?还难?那就简单点吧。”
“联系代理IntelliJ IDEA领取任务,他已经拿到了。”
“可以问一个问题吗,先生?”
“说话。”
“先生,为什么称 IntelliJ IDEA 为代理?它只是一个程序。”
“你只是一个程序。”
“IDEA 是一种人工智能,也是我们船上的一名船员。都清楚了吗?快走吧。”
“是,长官!执行您的命令,长官。”
8
任务
Java Collections, 第 3 级, 课程 15
Space (part 1)
Let's write a new computer game.
We'll have a spaceship that will shoot rockets at UFOs.
For their part, the UFOs will lob bombs at the spaceship.
And, of course, all this is happening in outer space.
We're going to need the following classes: Space, Spaceship, and Ufo.
8
任务
Java Collections, 第 3 级, 课程 15
Space (part 2)
We will have bombs and rockets.
That means we need Bomb and Rocket classes.
Create them.
Our classes will have a lot in common.
They will move about in space and be drawn on the screen.
That means that they'll all have coordinates and a size.
8
任务
Java Collections, 第 3 级, 课程 15
Space (part 3)
Why do we need the Space class?
To store all the objects and control how they interact.
What fields should it have?
width and height.
What else?
8
任务
Java Collections, 第 3 级, 课程 15
Space (part 4)
What is Space class missing?
That's right! run() and draw() methods.
If you recall, the run method manages all the game logic.
And the draw method is responsible for drawing the next "frame".
We'll also benefit from a sleep(int ms) method.
8
任务
Java Collections, 第 3 级, 课程 15
Space (part 5)
Now let's move on to the BaseObject class.
I want to make some suggestions.
First, for simplicity, treat all of our objects in space as circles.
We'll draw them as shapes, just as before.
But when calculating object collisions, we'll assume they are round.
Doing it this way is much simpler.
14
任务
Java Collections, 第 3 级, 课程 15
Space (part 6)
But there's more.
The BaseObject class needs more methods.
For now, these will be empty draw() and move() methods.
Subclasses will have to override them and implement the necessary functionality.
Also add a die() method, which causes the object to die (isAlive = false).
8
任务
Java Collections, 第 3 级, 课程 15
Space (part 7)
Now let's tackle the Canvas class.
It will contain a matrix that we will "draw" on.
The matrix has a width and height.
And we'll use it to store characters (chars) rather than numbers (ints).
28
任务
Java Collections, 第 3 级, 课程 15
Space (part 8)
What are we going to do with Canvas?
We'll draw on it (on its matrix).
Therefore, we need two methods:
public void setPoint(double x, double y, char c),
public void drawMatrix(double x, double y, int[][] matrix, char c).
8
任务
Java Collections, 第 3 级, 课程 15
Space (part 9)
Canvas needs another two methods. Write them.
a) the clear() method();
This method will clear the matrix so it can be drawn on again.
For example, replace all characters in the matrix with spaces.
b) the print() method();
This method draws the matrix on the screen.
8
任务
Java Collections, 第 3 级, 课程 15
Space (part 10)
Now we'll write the Bomb class. Everything is simple here.
Bomb inherits BaseObject.
Here's what we need:
a) change the constructor.
8
任务
Java Collections, 第 3 级, 课程 15
Space (part 11)
Now we'll write the Rocket class.
It's almost the same as the Bomb class.
But:
a) Rockets fly upward (i.e. y is decreased by 1);
b) We'll draw 'R' instead of 'B'.
8
任务
Java Collections, 第 3 级, 课程 15
Space (part 12)
Now let's do the ship.
For complexity, we'll do this: if the user presses the left button, the ship will start moving to the left and continue to do so.
If the user presses the right button, it will start moving to the right and continue to do so until it hits the edge.
14
任务
Java Collections, 第 3 级, 课程 15
Space (part 13)
We now turn to the draw and move methods.
In the move() method, you need to:
a) increase x by dx;
b) check to see whether the ship has moved beyond the boundaries of outer space [0, Space.game.getWidth()]. Use the checkBorders method.
Bear in mind that the ship's width is equal to twice its radius.
14
任务
Java Collections, 第 3 级, 课程 15
Space (part 14)
Now write the Ufo class.
It's a bit more complicated than the Bomb class and simpler than Spaceship.
You will need draw(), move(), and fire() methods.
Also, don't forget about the constructor. The parameters are doubles, and UFO's radius will be equal to 3.
8
任务
Java Collections, 第 3 级, 课程 15
Space (part 15)
We still have to finish the Space class.
Implement the getAllItems method:
The method should return one common list of all BaseObject objects.
Implement the moveAllItems method:
The method should move all the objects all at the same time.
14
任务
Java Collections, 第 3 级, 课程 15
Space (part 16)
And a little bit more:
Implement the createUfo() method:
If the list of UFOs is empty, create a ship in the center at the top of the screen.
Implement the checkBombs() method:
You need to check whether a bomb collided with the ship.
8
任务
Java Collections, 第 3 级, 课程 15
Space (part 17)
We need to finish the draw() method.
We'll do something similar with the move method. I'll write it myself today.
8
任务
Java Collections, 第 3 级, 课程 15
Space (part 18)
Make width and height bigger and you can play!
Enjoy the game :)