[Windows10][jdk15] 객체 지향 프로그래밍(OOP) Java 실습 13 - 앞면 나올 확률 설정한 후 동전 던지기

 

 [ 작업 환경 ]

 

Windows10

jdk-15

 

 

 

 

 

 [ 문제 ]

 

•	첨부되는 Coin 클래스를 확장(extend)하여 UnfairCoin 클래스를 만들어 보시오. UnfairCoin 클래스는 앞면이 90% 확률로 나오고 뒷면이 10%로 나오는 coin을 나타내도록 하시오. 
•	CountFlips.java 를 수정하여 UnfairCoin이 90% 확률로 앞면이 나오는지 double 값 형태로 계산하여 나타내시오.
•	아래와 같이 cmd 입력창에서 결과를 확인할 수 있어야 한다.
java CountFlips

 

UnfairCoin.java_part 파일 참조

public class UnfairCoin extends Coin {
    private double HeadProb;
    public UnfairCoin(double inputHeadProb) {
        //Add your logic
    }
   
    public void flip () {
        //Add your logic
   }
    
}

 

 

 

 

 

1. Coin.java

 

50% 확률로 앞, 뒷면이 나오는 코인 객체 예시

 >>> 90% 확률로 앞이 나오는 코인 객체 만들기 전에 참고용으로만 보시면 됩니다.

//********************************************************************
//  Coin.java       Java Foundations
//
//  Represents a coin with two sides that can be flipped.
//********************************************************************

public class Coin
{
   protected final int HEADS = 0;  // tails is 1
   protected final int TAILS = 1;  // tails is 1

   protected int face;  // current side showing

   //-----------------------------------------------------------------
   //  Sets up this coin by flipping it initially.
   //-----------------------------------------------------------------
   public Coin ()
   {
      flip();
   }

   //-----------------------------------------------------------------
   //  Flips this coin by randomly choosing a face value.
   //-----------------------------------------------------------------
   public void flip ()
   {
      face = (int) (Math.random() * 2);
   }

   //-----------------------------------------------------------------
   //  Returns true if the current face of this coin is heads.
   //-----------------------------------------------------------------
   public boolean isHeads ()
   {
      return (face == HEADS);
   }

   //-----------------------------------------------------------------
   //  Returns the current face of this coin as a string.
   //-----------------------------------------------------------------
   public String toString()
   {
      return (face == HEADS) ? "Heads" : "Tails";
   }
}

 

 

 

 

 

2. UnfairCoin.java 작성

 

public class UnfairCoin extends Coin {
    private double HeadProb;
    protected final int HEADS = 0;  // tails is 1
    public UnfairCoin(double inputHeadProb) {
        //Add your logic
        HeadProb = inputHeadProb;
        flip();
    }
   
    public void flip () {
        //Add your logic
        face = (int) (Math.random() / HeadProb);
   }

   //-----------------------------------------------------------------
   //  Returns true if the current face of this coin is heads.
   //-----------------------------------------------------------------
   public boolean isHeads ()
   {
      return (face == HEADS);
   }

   //-----------------------------------------------------------------
   //  Returns the current face of this coin as a string.
   //-----------------------------------------------------------------
   public String toString()
   {
      return (face == HEADS) ? "Heads" : "Tails";
   }
    
}

 

 

 

 

 

3. CountFlips.java 작성

 

앞면이 나올 확률을 입력받아 결과값을 출력합니다.

//********************************************************************
//  CountFlips.java       Java Foundations
//
//  Demonstrates the use of a programmer-defined class.
//********************************************************************
import java.util.Scanner;

public class CountFlips
{
   //-----------------------------------------------------------------
   //  Flips a coin multiple times and counts the number of heads
   //  and tails that result.
   //-----------------------------------------------------------------
   public static void main (String[] args)
   {
      final int FLIPS = 50000;
      int heads = 0, tails = 0;
      Scanner scan = new Scanner(System.in);
      System.out.println("Enter the head probability:");
      double headProb = scan.nextDouble();

      UnfairCoin myCoin = new UnfairCoin((double)headProb);

      for (int count=1; count <= FLIPS; count++)
      {
         myCoin.flip();

         if (myCoin.isHeads())
            heads++;
         else
            tails++;
      }

      System.out.println ("Number of flips: " + FLIPS);
      System.out.println ("Number of heads: " + heads);
      System.out.println ("Number of tails: " + tails);
   }
}

 

 

 

 

 

4. 소스 실행 예시