Java投掷模拟器问题

Question

hi i am doing a coin toss simulator for java that must be done a certain way. it must have a string for sideup to hold the string of "heads" or "tails" made by a no arg constructor, the toss method must be void and it must have a getsideup method, then we must run the coin toss 20 times and diplay the number of heads and tails... i can do it easy with none void methods and just returning the result, but getting around this void and getsideup is driving me nuts. this is what i have so far.

import java.util.Random;
public class coin {
    public static String sideUp;

    public static void toss() {
        Random rand = new Random();
        int sideup = rand.nextInt(2);
        if (sideup == 0) {
            sideUp = "heads";
        } else {
            sideUp = "tails";
        }
    }

    public static String getsideup() {
        System.out.println(sideUp);
        return sideUp;
    }

    public static void main(String[] args) {
        // coin coin = new coin();
        int hcount = 0;
        int tcount = 0;
        for (int i = 1; i <= 20; i++) {
            if (getsideup().equals("heads")) {
                hcount++;
            } else {
                tcount++;
            }
        }
        System.out.println("total heads = " + hcount + " total tails = " + tcount);
    }
}

im hoping someone can tell me what im doing wrong and put me in the right direction.

Answer 1

You're not calling toss() at the beginning of your loop. That's required to set a value to sideUp, and required to give sideUp to change every toss.

Answer 2

The simple fix is put toss in your for loop before the if statement but I see a lot that can be done here. First I would add a constructor for the Coin class and add hcount and tcount to the class variables and make heads and tails constants:

private String sideUp;
private int hcount;
private int tcount;
private static final String HEADS = "Heads";
private static final String Tails = "Tails";

Coin()
{
    this.sideUp = HEADS;
    this.hcount = 0;
    this.tcount = 0;
}

Then I would make a method to check the toss:

public  void checkToss()
{
    if (getsideup().equals(HEADS)) 
        hcount++;
    else
        tcount++;
}

Now add the toss() and checkCoin() method to the for loop before the if statement. It should look like this:

for (int i = 1; i <= 20; i++)
{
    coin.toss(); 
    coin.checkToss();
}

I would also make a getter for the heads count and tails count:

public int getHeadsCount()
{
    return this.hcount;
}

public int getTailsCount()
{
    return this.tcount;
}

Everything put together looks like this:

import java.util.Random;
public class Coin 
{
    private  String sideUp;
    private int hcount;
    private int tcount;
    private static final String HEADS = "Heads";
    private static final String TAILS = "Tails";

    Coin()
    {
        this.sideUp = HEADS;
        this.hcount = 0;
        this.tcount = 0;
    }

    public void toss()
    {
        Random rand = new Random();
        int sideup = rand.nextInt(2);
        if (sideup == 0) 
            sideUp = HEADS;
        else 
            sideUp = TAILS;    
    }

    public String getsideup()
    {
        System.out.println(sideUp);
        return sideUp;
    }

    public void checkToss()
    {
    if (getsideup().equals(HEADS)) 
        this.hcount++;
    else
        this.tcount++;
    }

    public int getHeadsCount()
    {
        return this.hcount;
    }

    public int getTailsCount()
    {
        return this.tcount;
    }

    public static void main(String[] args)
    {
        Coin coin = new Coin();
        for (int i = 1; i <= 20; i++) 
        {
            coin.toss();
            coin.checkToss();
        }
        System.out.println("Total Heads = " + coin.getHeadsCount() + " Total Tails = " + coin.getTailsCount());
    }
}

Answer 3

What about this ?

import java.io.*;
import java.math.*;
class Coin_Toss {
public static void main(String args[])throws Exception {
    InputStreamReader ir = new InputStreamReader(System.in);
    BufferedReader br = new BufferedReader(ir);
    double d, drop, side, s_d, re=1;
    int tries=0, score=0;
    while(re==1) {
        tries++;
        System.out.println("-> Hi, please choose your side\n-> Press 1 for    Head\n-> Press 2 for Tails");
        side=Integer.parseInt(br.readLine());
        drop=Math.random();
        d = Math.round(drop);
        if(d== 0) {
            s_d = 1;
        }
        else {
          s_d = 2;
        }
        if(s_d == side) {
            System.out.println("-> You Won");
            score++;
        }
        else {
            System.out.println("-> You Lose");
        }
        if(s_d==1) {
           System.out.println("->Its Heads");
        }
        else if(s_d==2) {
           System.out.println("-> Its tails");
        }
        System.out.println("-> Press 1 to Toss again \n -> Press 2 to     Quit");
        re=Double.parseDouble(br.readLine());
        if(re==2) {
            System.out.println("You Scored "+score+" out of "+tries);
        }
    }
}
}

Answer 4

for(int i = 1; i <= 20; i++) 
    {
        toss();
      if (getsideup().equals("heads")) 
      {
        hcount++;
      } else 
      {
        tcount++;
      }
    }

Answer 5

import java.util.Random;
public class coin
{
public static String sideUp;
public int hcount=0;
public int tcount=0;

public static void toss()
     {
        Random rand = new Random();
        int sideup = rand.nextInt(2);
        if (sideup == 0)
            {
                sideUp = "heads";
                hcount++;
            }
            else 
            {
                sideUp  = "tails";
                tcount++;
            } 
      }       

  public static void main(String[] args)
  {
    for(int i=0;i<20;i++)
    {toss();}
    System.out.println("total heads = " + hcount + " total tails = " + tcount);
   }
}