Question

好的，现在我得到了我的输出但是，一切似乎都不合适。我试了好几天。现在我更多地了解多线程。如何获得我预期的输出？有人可以告诉我哪个部分做错了吗？

这是我的测试程序

import java.util.*;

public class Test
{

public static void main (String[]args)
{
int totalShares = 0;
double totalCost = 0.0;
double totalProfitLoss = 0.0; 
int rand1 = 0;
double rand2 = 0.0;
Stock stock = new Stock("FCS",totalShares,totalCost,totalProfitLoss);

System.out.println ("Tracking of stock:  " +stock.name);
BuyThread bt = new BuyThread (rand1 , rand2 , stock);
SellThread st = new SellThread (rand1 , rand2 , stock);
bt.start();
st.start();

try
{
bt.join();
st.join();


System.out.println ("At$ 36.00 per share, profit is " + stock.getProfit(36.00));
}
catch (InterruptedException e)
{}
}
}

这是我的股票类

import java.util.*;
public class Stock
{
String name;
int totalShares;
double totalCost; 
double totalProfitLoss;


public Stock(String name, int totalShares, double totalCost,double totalProfitLoss )
{
    this.name = name;
    this.totalShares = totalShares;
    this.totalCost = totalCost;
    this.totalProfitLoss = totalProfitLoss;
} 

public String getName()
{
    return name;
}
public double getTotalShares () 
{
    //totalShares++;
    return totalShares;
}
public double getTotalCost () 
{
   // totalCost++;
    return totalCost;
}
public double getTotalProfitLoss() 
{

    return totalProfitLoss;
}



public void buy(int shares, double pricePerShare)
{
    totalShares += shares;
    totalCost += shares * pricePerShare;
    System.out.println ("Total shares now at " +totalShares+ " at total cost $ " +totalCost);

}

public boolean sell(int shares, double pricePerShare) 
{
  double sellCost = shares * pricePerShare;


  if (shares >= totalShares || sellCost >= totalCost){

      return false;

    }
    else {
      totalShares -= shares;
      totalCost -= sellCost;

      System.out.println ("Total shares now at " +totalShares+ " at total cost $ "+totalCost);   

        return true;

    }

}

public double getProfit (double currentPrice)
{
    totalProfitLoss = currentPrice * totalShares;
    return totalProfitLoss - totalCost;
}

}

这是我的BuyThread计划

import java.util.*;
public class BuyThread extends Thread
{
private int rand1 ;
private double rand2;
private Stock stock;

public BuyThread (int rand1,double rand2,Stock stock)
{
this.rand1 = rand1 ;
this.rand2 = rand2 ;
this.stock = stock;
}

public void run()
{
for (int j = 0 ; j < 2; j++)
{
Random randShare = new Random ();
int rand1 = randShare.nextInt (50) + 5 ;
double rand2 = (int) ((Math.random() * 10 + 32)* 100.0)/100.0 ;

stock.buy (rand1, rand2);
System.out.println (rand1+ " shares has been brought at $"+rand2) ;


try
{ sleep (50);
}
catch (InterruptedException e)
{}
}
}
}

这是我的SellThread

import java.util.*;
public class SellThread extends Thread
{
private int rand1 ;
private double rand2;
private Stock stock;

public SellThread (int rand1,double rand2,Stock stock)
{
this.rand1 = rand1 ;
this.rand2 = rand2 ;
this.stock = stock;
}

public void run()
{
for (int j = 0 ; j < 2; j++)
{
Random randShare = new Random ();
int rand1 = randShare.nextInt (20) + 20 ;
double rand2 = (int) ((Math.random() * 32 + 23)* 100.0)/100.0 ;

stock.sell (rand1 , rand2);
System.out.println (rand1+" shares has been sold at $"+rand2) ;


try
{
Thread.sleep(30);
}
catch (InterruptedException e)
{}
}
}
}

我得到了这个输出：

Tracking of stock:  FCS
Sell Total shares now at 13 at total cost $ 381.0999999999997
Buy Total shares now at 50 at total cost $ 1664.9999999999998
37 shares has been sold at $34.7
50 shares has been brought at $33.3
32 shares has been sold at $51.97
Buy Total shares now at 18 at total cost $ 555.1499999999996
5 shares has been brought at $34.81
At$ 36.00 per share, profit is 92.85000000000036

我期待输出：

Tracking of Stock : FCS
8 shares has been brought at $37.61
Total shares now 8 at total cost $300.88
33 shares has been brought at $36.31
Total shares now 41 at total cost $1499.11  
17 shares has been sold at $42.67
Total shares now 24 at total cost $773.72
19 shares has been sold at $32.31
Total shares now 5 at total cost $159.83
31 shares has been brought at $33.85
Total shares now 36 at total cost $1209.18
28 shares has been brought at $36.37
Total shares now 64 at total cost $2227.54
20 shares has been brought at $35.49
Total shares now 84 at total cost $2937.34
At $36.00 per share, profit is $86.66

Answer 1

使用wait并通过synchronized

通知

等待使线程等待并通知唤醒其他等待线程。

请填写条件等待状态和通知条件相同。

synchronized public void buy(int shares, double pricePerShare)
    {
        if(totalShares>0)
        {
          wait();
        }
        totalShares += shares;
        totalCost += shares * pricePerShare;
        System.out.println ("Total shares now at " +totalShares+ " at total cost $ " +totalCost);
        notify();
    }

    synchronized public void sell(int shares, double pricePerShare) 
    {
      double sellCost = shares * pricePerShare;


        if (shares >= totalShares || sellCost >= totalCost)
        {
         wait();
        }
        else 
        {
          totalShares -= shares;
          totalCost -= sellCost;
          System.out.println ("Total shares now at " +totalShares+ " at total cost $ "+totalCost);   
          notify();
        }

    }

输出多线程的顺序不正确

1 个答案: