multithreading - Simple Traffic Light Simulation with Java Threads -

as questions states, trying make very, simple traffic light simulation of 4 way intersection. problem is, using 2 different threads , trying bounce , forth between 2 using wait , notify while inside loop. have psuedo code below.

public class processor  {     public static int carcounter = 1;      public void lightoneandtwo() throws interruptedexception     {         synchronized(this)         {             for(int carsone = 0; carsone < 50; carsone++)             {                 //light one---------------------------->                   //light two---------------------------->                  wait();             }         }     }     public void lightthreeandfour() throws interruptedexception     {         thread.sleep(1000);          synchronized(this)         {             for(int carstwo = 0; carstwo < 50; carstwo++ )             {                 //light three---------------------------->                  notify();              }         }     } } 

but when call notify, not reactivate the first thread. doing wrong or there better way it?

your program have multiple issues - no conditional variable, no while loop check condition etc. below 1 possible solution. have 4 classes:

mylock - (lock object)

package com.test;  public class mylock {      private volatile boolean condition;      public mylock(boolean condition) {         this.condition = condition;     }      public boolean condition() {         return condition;     }      public void flipcondition() {         condition = !condition;     } } 

trafficlightworkerone (traffic worker)

package com.test;  public class trafficlightworkerone implements runnable {      private int cars;     private mylock lock;      public trafficlightworkerone(mylock lock, int cars) {         this.lock = lock;         this.cars = cars;     }      @override     public void run() {         while (true) {             synchronized (lock) {                 while (!lock.condition()) {                     (int carsone = 0; carsone < cars; carsone++) {                          system.out.println(thread.currentthread().getname()                                 + " car no : " + carsone);                         // light one---------------------------->                          // light two---------------------------->                     }                     lock.notifyall();                     lock.flipcondition();                 }                 try {                     lock.wait();                 } catch (interruptedexception e) {                     // todo auto-generated catch block                     e.printstacktrace();                 }             }         }     } } 

trafficlightworkertwo (another traffic worker)

package com.test;  public class trafficlightworkertwo implements runnable {      private int cars;     private mylock lock;      public trafficlightworkertwo(mylock lock, int cars) {         this.lock = lock;         this.cars = cars;     }      @override     public void run() {          while (true) {             synchronized (lock) {                 try {                     while (!lock.condition()) {                         lock.wait();                     }                 } catch (interruptedexception e) {                     // todo auto-generated catch block                     e.printstacktrace();                 }                  (int carsone = 0; carsone < cars; carsone++) {                      system.out.println(thread.currentthread().getname()                             + " car no : " + carsone);                     // light one---------------------------->                      // light two---------------------------->                 }                 lock.flipcondition();;                 lock.notifyall();             }         }      } } 

trafficlightsimulator (main class)

package com.test;  public class trafficlightsimulator {      public static void main(string[] args) {         boolean  condition = false;          mylock lock = new mylock(condition);         thread threadone = new thread(new trafficlightworkerone(lock, 5), "one");         thread threadtwo = new thread(new trafficlightworkertwo(lock, 4), "two");          threadone.start();         threadtwo.start();      } }