卡住多線程java

Question

所以這段代碼在main中給出了多個錯誤。有人能告訴我這有什麼問題嗎？第一次海報所以請溫柔

問題是要創建消費者和生產者線程做燈。只有兩個消費者是允許的，那裏有一個生產者線程的燈的每一個組件

public class ProducerConsumerTest{ 




    public static void main(String[] args){ 

     StartProducer startproducer = new StartProducer(); 
     System.out.println("Start producer calling"); 
     startproducer.start(); 


    } 
} 
class StartProducer extends Thread{ 

    Screw screw = new Screw(); 
    Base base = new Base(); 
    Stand stand = new Stand(); 
    Socket socket = new Socket(); 
    LightBulb lightbulb = new LightBulb(); 
    int screws = screw.screwcount; 
    int bases = base.basecount; 
    int stands = stand.standcount; 
    int sockets = socket.socketcount; 
    int lightbulbs = lightbulb.bulbcount; 
    Consumer1 consumer1 = new Consumer1(); 
    Consumer2 consumer2 = new Consumer2(); 
    public synchronized void run(){ 

     System.out.println("producer test"); 

      screw.start(); 


      base.start(); 


      stand.start(); 


      socket.start(); 


      lightbulb.start(); 




     boolean possible = possibleToBuildLamp(screws,bases,stands,sockets,lightbulbs); 
     if(possible == true){ 
      consumer1.start(); 
      consumer2.start(); 

     } 
    } 

    private boolean possibleToBuildLamp(int screws, int bases, int stands, 
      int sockets, int lightbulbs) { 
     if(screws>=4 && bases>=1 && stands>=1 && sockets>=3 && lightbulbs>=3){ 
      return true; 
     } 

     else return false; 
    } 

} 
class Screw extends Thread{ 

    public int screwcount; 
    public synchronized void run(){ 
     while(true){ 
     if(screwcount>=0 && screwcount<7){ 
      screwcount++; 
     } 
     try { 
      wait(); 
     } catch (InterruptedException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
     } 
    } 

} 
} 

class Base extends Thread{ 
    public int basecount; 
    public synchronized void run(){ 

    while(true){ 
     if(basecount>=0 && basecount <2){ 
      basecount++; 
     } 
     try { 
      wait(); 
     } catch (InterruptedException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
     } 
    } 

} 
} 

class Stand extends Thread { 
    public int standcount; 
    public synchronized void run(){ 

    while(true){ 
     if(standcount>=0 && standcount<2){ 
      standcount++; 
     } 
    } 

} 
} 

class Socket extends Thread { 
    public int socketcount; 
    public synchronized void run(){ 

    while(true){ 
     if(socketcount>=0 && socketcount<7){ 
      socketcount++; 
     } 
     try { 
      wait(); 
     } catch (InterruptedException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
     } 
    } 

} 
} 

class LightBulb extends Thread { 
    public int bulbcount; 
    public synchronized void run(){ 

    while(true){ 

     if(bulbcount>=0 && bulbcount<4){ 
      bulbcount++; 
     } 
     try { 
      wait(); 
     } catch (InterruptedException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
     } 
    } 

} 
} 



class Consumer1 extends Thread { 
    ProducerConsumerTest test = new ProducerConsumerTest(); 
    StartProducer start = new StartProducer(); 


    public synchronized void run(){ 
     while(true){ 
     Screw screw = new Screw(); 
     Base base = new Base(); 
     Stand stand = new Stand(); 
     Socket socket = new Socket(); 
     LightBulb lightbulb = new LightBulb(); 

     screw.screwcount-=4; 
     base.basecount-=1; 
     stand.standcount-=1; 
     socket.socketcount-=3; 
     lightbulb.bulbcount-=3; 
     System.out.println("one lamp made"); 
     start.notify(); 

     try { 
      wait(); 
     } catch (InterruptedException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
     } 
     } 


    } 


} 

class Consumer2 extends Thread { 
ProducerConsumerTest test = new ProducerConsumerTest(); 
StartProducer start = new StartProducer(); 

    public synchronized void run(){ 

     while(true){ 
     Screw screw = new Screw(); 
     Base base = new Base(); 
     Stand stand = new Stand(); 
     Socket socket = new Socket(); 
     LightBulb lightbulb = new LightBulb(); 

     screw.screwcount-=4; 
     base.basecount-=1; 
     stand.standcount-=1; 
     socket.socketcount-=3; 
     lightbulb.bulbcount-=3; 
     System.out.println("One lamp made"); 
     start.notify(); 
     try { 
      wait(); 
     } catch (InterruptedException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
     } 



     }  

    } 

} 

Answer 1

在主創建StartProducer：

StartProducer startproducer = new StartProducer(); 

它創建了一個Consumer1：

Consumer1 consumer1 = new Consumer1(); 

這創建另一個新的StartProducer：

StartProducer start = new StartProducer(); 

這將新建另一個新的Consumer1。它將無法執行其他任何操作，因爲它會被卡住，創建一個無限長的線段StartProducer s，直到用StackOverlowError消除。對於Consumer2也是如此，如果它能夠創造這些。

如果您只需要一個StartProducer對象，則需要在一個位置創建它，並將引用傳遞給其他需要它的對象，例如將其引用到其構造函數的參數或放入其中一個共享變量，他們可以訪問它。

P.S.您所有線程的run()方法都是​​，它們沒有實現任何互斥，因爲每個線程都在不同的對象上進行同步：線程本身。如果您想提供有用的互斥，則需要使用synchronized statement來同步由多個線程共享的特定對象。