【从零学java】猜数字游戏——了解类与对象

通过猜数字游戏，开始了解类和对象。

游戏概要：产生一个0-9间的随机数，3个player猜，若有猜中者则游戏结束，猜不中下一轮继续猜。

类：GuessGame.class、Player.class、GameLauncher.class

逻辑：

1）GameLauncher作为程序的入口，含有main()方法。

2）main()中创建GuessGame对象，并调用它的startGame()方法。

3）startGame()方法是游戏的起点，创建3个player，然后猜数，并体现猜数的过程。

3个源文件的代码如下：

GuessGame.java

public class GuessGame{
	Player p1;
	Player p2;
	Player p3;

	public void startGame(){
		p1 = new Player();
		p2 = new Player();
		p3 = new Player();

		int guessp1 = 0;
		int guessp2 = 0;
		int guessp3 = 0;

		boolean p1isRight = false;
		boolean p2isRight = false;
		boolean p3isRight = false;

		int resultNum = (int)(Math.random()*10);
		System.out.println("I'm thinking of a number between 0 and 9...");
		System.out.println("number to guess is "+resultNum);

		while(true){
			p1.guess();
			p2.guess();
			p3.guess();

			guessp1 = p1.number;
			guessp2 = p2.number;
			guessp3 = p3.number;

			if(guessp1 == resultNum){
				p1isRight = true;
			}
			if(guessp2 == resultNum){
				p2isRight = true;
			}
			if(guessp3 == resultNum){
				p3isRight = true;
			}

			System.out.println("player one guessed " + guessp1);
			System.out.println("player two guessed " + guessp2);
			System.out.println("player three guessed " + guessp3);

			if(p1isRight || p2isRight|| p3isRight){
				System.out.println("we have a winner!");
				System.out.println("one is winner? "+ p1isRight);
				System.out.println("two is winner? "+ p2isRight);
				System.out.println("three is winner? "+ p3isRight);
				System.out.println("Game is over.");
				break;
			}else{
				System.out.println("try again.");
			}
		}
	}
}

　　

Player.java

public class Player{
	int number = 0;

	public void guess(){
		number = (int) (Math.random()*10);
		System.out.println("I guess "+number);
	} 
}

　　

GameLauncher.java

public class GameLauncher{
	public static void main(String[] args){
		GuessGame game = new GuessGame();
		game.startGame();
	}
}

　　三个文件在同一个目录下，编译时，直接编译带main()方法的源文件，所有相关的源文件都会被编译。

执行如下（每次执行都会不一样，有时会猜好多轮）：

要理解的点：

1、如果需要全局变量或者方法时，怎么办？

在java的面向对象概念中，并没有全局变量这回事，有时我们需要