第三章第十七题（游戏：剪刀、石头、布）(Game: scissor, rock, paper)

*3.17（游戏：剪刀、石头、布）编写可以玩流行的剪刀-石头-布游戏的程序。（剪刀可以剪布，石头可以砸剪刀，而布可以包石头。）程序提示用户随机产生一个数，这个数为0、1或者2，分别表示石头、剪刀和布。程序提示用户输入值0、1或者2，然后显示一条消息，表明用户和计算机谁赢了游戏，谁输了游戏，或是打成平手。

下面是运行示例：
scissor(0),rock(1),paper(2): 1
The computer is scissor.You are rock.You won
scissor(0),rock(1),paper(2): 2
The computer is paper.You are paper too.It is a draw

*3.17(Game: scissor, rock, paper) Write a program that plays the popular scissor–rock–paper game. (A scissor can cut a paper, a rock can knock a scissor, and a paper can wrap a rock.) The program randomly generates a number 0, 1, or 2 representing scissor, rock, and paper. The program prompts the user to enter a number 0, 1, or 2 and displays a message indicating whether the user or the computer wins, loses, or draws.

Here are sample runs:
scissor(0),rock(1),paper(2): 1
The computer is scissor.You are rock.You won
scissor(0),rock(1),paper(2): 2
The computer is paper.You are paper too.It is a draw

下面是参考答案代码:

import java.util.*;

public class ScissorRockPaperQuestion17 {
	public static void main(String[] args) {
		// Generate the computer's guess
		final int userGuess,computerGuess = (int)(Math.random()*3);
		
		// Prompt the user to enter a guess
		System.out.print("scissor(0),rock(1),paper(2): ");
		Scanner input = new Scanner(System.in);
		userGuess = input.nextInt();
		
		// Check user's guess and Display the result
		if(computerGuess == 0)	// The situation that computer guess is a scissor
		{
			if(userGuess == 0)
			{
				System.out.print("The computer is scissor.");
				System.out.print("You are scissor too.");
				System.out.print("It is a draw");
			}
			else if(userGuess == 1)
			{
				System.out.print("The computer is scissor.");
				System.out.print("You are rock.");
				System.out.print("You won");
			}
			else if(userGuess == 2)
			{
				System.out.print("The computer is scissor.");
				System.out.print("You are paper.");
				System.out.print("You lost");
			}
		}
		else if(computerGuess == 1) // The situation that computer guess is a rock
		{
			if(userGuess == 0)
			{
				System.out.print("The computer is rock.");
				System.out.print("You are scissor.");
				System.out.print("You lost");
			}
			else if(userGuess == 1)
			{
				System.out.print("The computer is rock.");
				System.out.print("You are rock too.");
				System.out.print("It is a draw");
			}
			else if(userGuess == 2)
			{
				System.out.print("The computer is rock.");
				System.out.print("You are paper.");
				System.out.print("You won");
			}
		}
		else //The situation that computer guess is a paper
		{
			if(userGuess == 0)
			{
				System.out.print("The computer is paper.");
				System.out.print("You are scissor.");
				System.out.print("You won");
			}
			else if(userGuess == 1)
			{
				System.out.print("The computer is paper.");
				System.out.print("You are rock.");
				System.out.print("You lost");
			}
			else if(userGuess == 2)
			{
				System.out.print("The computer is paper.");
				System.out.print("You are paper too.");
				System.out.print("It is a draw");
			}
		}
		
		// Display invalid situation
		if(userGuess > 2 || userGuess < 0)
		{
			System.out.println("Error:Invalid Guess");
			System.exit(1);
		}
		input.close();
	}
}

运行效果：

注：编写程序要养成良好习惯
如：1.文件名要用英文，具体一点
2.注释要英文
3.变量命名要具体，不要抽象（如:a,b,c等等），形式要驼峰化
4.整体书写风格要统一（不要这里是驼峰，那里是下划线，这里的逻辑段落空三行，那里相同的逻辑段落空5行等等）