错误的输出顺序多线程

Question

好吧，现在我得到了我的输出，但是，一切似乎没有按顺序。我试了几天，几天。现在我更了解多线程。我如何得到我期望的输出？有人能告诉我我错误地做了哪一部分？

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BuyThread程序

---

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) 
{} 
} 
} 
}  

我得到这样的输出：

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 

我期待一个输出：

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

使用等待和通知与同步

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(); 
     } 

    }