Create two threads one display odd other even numbers

Question

I m trying to create two threads  one thread display even integers from 0 to 10  one thread display odd integers from 1 to 11  Is the following code suitable for designing this program   public class Mythread        public static void main String   args            Runnable r   new Runnable1            Thread t   new Thread r           t start            Runnable r2   new Runnable2            Thread t2   new Thread r2           t2 start             class Runnable2 implements Runnable      public void run            for int i 0 i lt 11 i                 if i 2    1                  System out println i                      class Runnable1 implements Runnable      public void run            for int i 0 i lt 11 i                 if i 2    0                  System out println i

User · Accepted Answer

I would just change a few details  no need to use the modulo operator here       public class Mythread        public static void main String   args            Runnable r   new Runnable1            Thread t   new Thread r           Runnable r2   new Runnable2            Thread t2   new Thread r2           t start            t2 start             class Runnable2 implements Runnable      public void run            for int i 0 i lt 11 i  2                System out println i                      class Runnable1 implements Runnable      public void run            for int i 1 i lt  11 i  2               System out println i

User · Answer

public class ThreadExample    Object lock   new Object     class ThreadEven implements Runnable         Override     public void run             int i   2          while  i  lt   20                synchronized  lock                    System out println i                         i   i   2                  lock notify                    try                       lock wait                      catch  InterruptedException e                        e printStackTrace                                                         class ThreadOdd implements Runnable         Override     public void run             int i   1          while  i  lt   20                synchronized  lock                    System out println i                         i   i   2                  try                       lock notify                        lock wait                      catch  InterruptedException e                         e printStackTrace                                                         public static void main String args           ThreadExample example   new ThreadExample        ThreadExample ThreadOdd odd   example new ThreadOdd        ThreadExample ThreadEven even   example new ThreadEven         Thread oT   new Thread odd       Thread eT   new Thread even        oT start        eT start

User · Answer

Below is the code which uses lock on a shared object which has the number to be printed  It guarantees the sequence also unlike the above solution   public class MultiThreadPrintNumber     int i   1     public synchronized void printNumber String threadNm  throws InterruptedException         if threadNm equals  t1             if i 2    1             System out println Thread currentThread   getName    --   i               notify              else             wait                      else if threadNm equals  t2             if i 2    0             System out println Thread currentThread   getName    --   i               notify              else             wait                                public static void main String   args        final MultiThreadPrintNumber obj   new MultiThreadPrintNumber        Thread t1   new Thread new Runnable             Override       public void run             try             while obj i  lt   10                obj printNumber Thread currentThread   getName                           catch  InterruptedException e                 TODO Auto-generated catch block           e printStackTrace                      System out println  done t1                        Thread t2   new Thread new Runnable             Override       public void run             try             while obj i  lt  10               obj printNumber Thread currentThread   getName                           catch  InterruptedException e                 TODO Auto-generated catch block           e printStackTrace                      System out println  done t2                         t1 setName  t1        t2 setName  t2        t1 start        t2 start            The output will look like  t1--1 t2--2 t1--3 t2--4 t1--5 t2--6 t1--7 t2--8 t1--9 t2--10 done t2 done t1

User · Answer

package p Threads   public class PrintEvenAndOddNum         private  Object obj   new Object         private static final PrintEvenAndOddNum peon   new PrintEvenAndOddNum         private PrintEvenAndOddNum          public static PrintEvenAndOddNum getInstance            return peon             public  void printOddNum              for int i 1 i lt 10 i                 if i 2    0                   synchronized  obj                        System out println i                        try                           System out println  oddNum going into waiting state                                 obj wait                           catch  InterruptedException e                               TODO Auto-generated catch block                         e printStackTrace                                              System out println  resume                            obj notify                                                         public  void printEvenNum              for int i 1 i lt 11 i                 if i 2    0                   synchronized obj                       System out println i                       obj notify                        try                           System out println  evenNum going into waiting state                                 obj wait                            System out println  Notifying waiting thread                               catch  InterruptedException e                               TODO Auto-generated catch block                         e printStackTrace

User · Answer

Pretty much all that is necessary if you are asked to print even odd numbers in synchronized manner   public class ThreadingOddEvenNumbers        void main String   args  throws InterruptedException           Printer printer   new Printer 57           Thread t1   new Thread new MyRunner printer  true    EvenPrinter            Thread t2   new Thread new MyRunner printer  false    OddPrinter            t1 start            t2 start             t1 join            t2 join              class MyRunner implements Runnable       private Printer p      private boolean evenProperty       public MyRunner Printer p  boolean evenNess            this p   p          evenProperty   evenNess             public void run             try               print              catch  InterruptedException ex                System out println this getClass   getName                               ex getMessage                           public void print   throws InterruptedException           while   p isJobComplete                  synchronized  p                    if  evenProperty                      while  p isEvenPrinted                              System out println  wait by                                      Thread currentThread   getName                             p wait                            if  p isJobComplete                                break                                        else                     while   p isEvenPrinted                              System out println  wait by                                      Thread currentThread   getName                             p wait                            if  p isJobComplete                                break                                                   synchronized  p                    if  evenProperty                      p printEven Thread currentThread   getName                     else                     p printOdd Thread currentThread   getName                     p notifyAll                    System out println  notify called  by                              Thread currentThread   getName                                      class Printer       private volatile boolean evenPrinted      private volatile boolean jobComplete      private int limit      private int counter       public Printer int lim            limit   lim          counter   1          evenPrinted   true          jobComplete   false             public void printEven String threadName            System out println threadName         counter           incrCounter            evenPrinted   true             public void printOdd String threadName            System out println threadName         counter           incrCounter            evenPrinted   false             private void incrCounter             counter            if  counter  gt   limit              jobComplete   true             public int getLimit             return limit             public boolean isEvenPrinted             return evenPrinted             public boolean isJobComplete             return jobComplete

User · Answer

package javaapplication45   public class JavaApplication45 extends Thread        public static void main String   args              even numbers         Thread t1   new Thread                 public void run                     for  int i   1  i  lt   20  i                          if  i   2    0                            System out println  even thread     i                                                                            t1 start              odd numbers         Thread t2   new Thread                 public void run                     for  int i   1  i  lt   20  i                          if  i   2    0                            System out println  odd thread     i                                                                            t2 start

User · Answer

public class OddEvenPrinetr       private static Object printOdd   new Object         public static void main String   args             Runnable oddPrinter    new Runnable                 int count   1               Override             public void run                     while true                       synchronized  printOdd                            if count  gt   101                               printOdd notify                                return                                                    System out println count                           count   count   2                                                                        try                               printOdd notify                                printOdd wait                              catch  InterruptedException e                                e printStackTrace                                                                                                         Runnable evenPrinter    new Runnable                 int count   0               Override             public void run                     while true                       synchronized  printOdd                            printOdd notify                            if count  gt   100                                                      return                                                                                           count   count   2                          System out println count                           printOdd notify                            try                               printOdd wait                              catch  InterruptedException e                                e printStackTrace                                                                                                        new Thread oddPrinter  start            new Thread evenPrinter  start

User · Answer

package com example   public class MyClass        static int mycount 0      static Thread t      static Thread t2      public static void main String   arg                t2 new Thread new Runnable                  Override             public void run                     System out print mycount       even  n                    try                       Thread sleep 500                     catch  InterruptedException e                        e printStackTrace                                      if mycount gt 25                      System exit 0                   run                                      t new Thread new Runnable                  Override             public void run                     System out print mycount       odd  n                    try                       Thread sleep 500                     catch  InterruptedException e                        e printStackTrace                                      if mycount gt 26                      System exit 0                   run                                      t start            t2 start

User · Answer

public class ConsecutiveNumberPrint    private static class NumberGenerator        public int MAX   100       private volatile boolean evenNumberPrinted   true       public NumberGenerator int max            this MAX   max             public void printEvenNumber int i  throws InterruptedException           synchronized  this                if  evenNumberPrinted                    wait                              System out println  e    t    i               evenNumberPrinted    evenNumberPrinted              notify                         public void printOddNumber int i  throws InterruptedException           synchronized  this                if   evenNumberPrinted                    wait                              System out println  o    t    i               evenNumberPrinted    evenNumberPrinted              notify                        private static class EvenNumberGenerator implements Runnable        private NumberGenerator numberGenerator       public EvenNumberGenerator NumberGenerator numberGenerator            this numberGenerator   numberGenerator              Override     public void run             for int i   2  i  lt   numberGenerator MAX  i  2              try                   numberGenerator printEvenNumber i                 catch  InterruptedException e                    e printStackTrace                           private static class OddNumberGenerator implements Runnable        private NumberGenerator numberGenerator       public OddNumberGenerator NumberGenerator numberGenerator            this numberGenerator   numberGenerator              Override     public void run             for int i   1  i  lt   numberGenerator MAX  i  2                try                   numberGenerator printOddNumber i                 catch  InterruptedException e                    e printStackTrace                                    public static void main String   args        NumberGenerator numberGenerator   new NumberGenerator 100       EvenNumberGenerator evenNumberGenerator   new EvenNumberGenerator numberGenerator       OddNumberGenerator oddNumberGenerator   new OddNumberGenerator numberGenerator       new Thread oddNumberGenerator  start        new Thread evenNumberGenerator  start

User · Answer

public class MyThread        public static void main String   args               TODO Auto-generated method stub          Threado o  new Threado            o start             Threade e new Threade            e start                      class Threade extends Thread       public void run             for int i 2 i lt 10 i i 2              System out println  evens   i                             class Threado extends Thread       public void run             for int i 1 i lt 10 i i 2              System out println  odds   i                              OUTPUT  -  odds 1 odds 3 odds 5 odds 7 odds 9 evens 2 evens 4 evens 6 evens 8

User · Answer

package thread   import org hibernate annotations Synchronize   class PrintOdd implements Runnable       int count   -1      private Object common       PrintOdd Object common            this common   common              Override     public void run             synchronized  common                while  count  lt  1000                    try                       common notifyAll                        System out println count    2                       common wait                      catch  InterruptedException e                           TODO Auto-generated catch block                     e printStackTrace                                                         class PrintEven implements Runnable        int count   0      private Object common       PrintEven Object common            this common   common              Override     public void run             synchronized  common                while  count  lt  1000                    try                       common notifyAll                        System out println count    2                       common wait                      catch  InterruptedException e                           TODO Auto-generated catch block                     e printStackTrace                                                         public class PrintNatural       public static void main String args              Object obj   new Object            Runnable r   new PrintOdd obj           Thread printOdd   new Thread r            Runnable r2   new PrintEven obj           Thread printEven   new Thread r2            printOdd start            printEven start

User · Answer

The Question should be  Print Odd-Even Numbers simultaneously Using Threads       public class EvenOdd1           static boolean flag   true          public static void main String   args                Runnable odd      - gt                    for  int i   1  i  lt   10                         if  EvenOddPrinter flag                            System out println Thread currentThread   getName           i                           i    2                          EvenOddPrinter flag    EvenOddPrinter flag                         if                    for                             Runnable even      - gt                    for  int i   2  i  lt   10                         if   EvenOddPrinter flag                            System out println Thread currentThread   getName           i                           i    2                          EvenOddPrinter flag    EvenOddPrinter flag                                                                      Thread t1   new Thread odd   Odd                Thread t2   new Thread even   Even                t1 start                t2 start                      The output   gt   Odd 1 Even 2 Odd 3 Even 4 Odd 5 Even 6 Odd 7 Even 8 Odd 9 Even 10

User · Answer

I would also look at using Java Concurrency if you want alternatives  Some of the functionality provided in the Java Concurrency package offer a higher level of abstraction then using the Thread class directly and provide more functionality as a result   For your specific case what your doing is quite reasonable however is the order of the printing of these numbers important  Do you want evens before odds  These kinds of questions would better indicate the design that most suits your needs

User · Answer

Yes it is fine  But in this case  I don t think you need 2 threads are all  because the operation is simple  However  if you are practicing threads  it is OK

User · Answer

public class EvenOddNumberPrintUsingTwoThreads        public static void main String   args               TODO Auto-generated method stub          Thread t1   new Thread                           public void run                      for  int i   0  i  lt   10  i                          if  i   2    0                            System out println  Even       i                                                                              Thread t2   new Thread                    int i 0              public void run                      for  int i   0  i  lt   10  i                          if  i   2    1                            System out println  Odd       i                                                                             t1 start            t2 start

User · Answer

Concurrent Package       import java util concurrent ExecutorService       import java util concurrent Executors      import java util concurrent Future      import java util concurrent locks Condition      import java util concurrent locks Lock      import java util concurrent locks ReentrantLock                    Task1 class prints odd           class TaskClass1 implements Runnable            private Condition condition      private Lock lock      boolean exit   false      int i      TaskClass1 Condition condition Lock lock                this condition   condition          this lock   lock             Override     public void run             try                       lock lock                for i   1 i lt 11 i                                  if i 2    0                                        condition signal                        condition await                                       if i 2    0                                        System out println Thread currentThread   getName          i                                                catch  Exception e                   TODO Auto-generated catch block             e printStackTrace             finally                       lock unlock                               Task2   prints even         class TaskClass2 implements Runnable        private Condition condition      private Lock lock      boolean exit   false      TaskClass2 Condition condition Lock lock                this condition   condition          this lock   lock             Override     public void run             int i             TODO Auto-generated method stub         try                       lock lock                for i   2 i lt 11 i                                    if i 2    0                                        condition signal                        condition await                                      if i 2    0                                        System out println Thread currentThread   getName          i                                                catch  InterruptedException e                   TODO Auto-generated catch block             e printStackTrace             finally                       lock unlock                         public class OddEven        public static void main String   a                Lock lock   new ReentrantLock            Condition condition   lock newCondition            Future future1          Future future2          ExecutorService executorService   Executors newFixedThreadPool 2            future1   executorService submit new TaskClass1 condition lock            future2   executorService submit new TaskClass2 condition lock            executorService shutdown

User · Answer

public class ThreadClass      volatile int i   1      volatile boolean state true       synchronized public void printOddNumbers                        try                          while   state                                wait                                                   catch  InterruptedException e                           e printStackTrace                                         System out println Thread currentThread   getName       i                         state   false                        i                          notifyAll              synchronized  public void printEvenNumbers           try             while  state                   wait                         catch  InterruptedException e              e printStackTrace                  System out println Thread currentThread   getName       i         state   true        i          notifyAll               Then call the above class like this        I am ttying to print 10 values    ThreadClass threadClass new ThreadClass             Thread t1 new Thread                int k 0               Override             public void run                     while  k lt 5                        threadClass printOddNumbers                        k                                                       t1 setName  Thread1            Thread t2 new Thread                int j 0               Override             public void run                     while  j lt 5                        threadClass printEvenNumbers                        j                                                       t2 setName  Thread2             t1 start             t2 start       Here I am trying to printing the 1 to 10 numbers  One thread trying to print the even numbers and another Thread Odd numbers  my logic is print the even number after odd number  For this even numbers thread should wait until notify from the odd numbers method  Each thread calls particular method 5 times because I am trying to print 10 values only    out put    System out  Thread1 1 System out  Thread2 2 System out  Thread1 3 System out  Thread2 4 System out  Thread1 5 System out  Thread2 6 System out  Thread1 7 System out  Thread2 8 System out  Thread1 9 System out  Thread2 10

User · Answer

Nos will be printed in sequence  Main class             package com thread   import java util concurrent atomic AtomicInteger   public class StartThread       static AtomicInteger no   new AtomicInteger 1       public static void main String   args            Odd oddObj   new Odd            Thread odd   new Thread oddObj           Thread even   new Thread new Even oddObj            odd start            even start             Odd Thread             package com thread   public class Odd implements Runnable         Override     public void run             while  StartThread no get    lt  20                synchronized  this                    System out println  Odd  gt     StartThread no get                     StartThread no incrementAndGet                     try                       this notify                        if StartThread no get      20                          break                      this wait                      catch  InterruptedException e                        e printStackTrace                                                         Even Thread             package com thread   public class Even implements Runnable       Odd odd       public Even Odd odd            this odd   odd              Override     public void run             while  StartThread no get    lt  20                synchronized  odd                    System out println  Even  gt     StartThread no get                     StartThread no incrementAndGet                    odd notifyAll                    try                       odd wait                      catch  InterruptedException e                           TODO Auto-generated catch block                     e printStackTrace                                                                 Output  Nos are printed in sequential         Odd  gt 1 Even  gt 2 Odd  gt 3 Even  gt 4 Odd  gt 5 Even  gt 6 Odd  gt 7 Even  gt 8 Odd  gt 9 Even  gt 10 Odd  gt 11 Even  gt 12 Odd  gt 13 Even  gt 14 Odd  gt 15 Even  gt 16 Odd  gt 17 Even  gt 18 Odd  gt 19

User · Answer

aymeric answer wont print the numbers in their natural order  but this code will  Explanation at the end   public class Driver       static Object lock   new Object         public static void main String   args            Thread t1   new Thread new Runnable                 public void run                      for  int itr   1  itr  lt  51  itr   itr   2                        synchronized  lock                            System out print       itr                           try                               lock notify                                lock wait                              catch  InterruptedException e                                e printStackTrace                                                                                                        Thread t2   new Thread new Runnable                 public void run                      for  int itr   2  itr  lt  51  itr   itr   2                        synchronized  lock                            System out print       itr                           try                               lock notify                                if itr  50                                  break                              lock wait                              catch  InterruptedException e                                e printStackTrace                                                                                                        try               t1 start                t2 start                t1 join                t2 join                System out println   nPrinting over              catch  Exception e                         In order to achieve so  the run methods of the two threads above have to be called one after the other  i e  they need to be synchronized and I am achieving that using locks    The code works like this  t1 run prints the odd number and notifies any waiting thread that it is going to release the lock  then goes into a wait state   At this point t2 run is invoked  it prints the next even number  notifies other threads that it is about to release the lock it holds and then goes into wait state   This continues till the itr in t2 run   reaches 50  at this point our goal has been achieved and we need to kill these two threads    By breaking  I avoid calling lock wait   in t2 run and t2 thread is thus shutdown  the control will now go to t1 run since it was waiting to acquire the lock  but here itr value will be   51 and we will come out of its run    thus shutting down the thread    If break is not used in t2 run    though we will see numbers 1 to 50 on the screen but the two threads will get into a deadlock situation and continue to be in wait state

User · Answer

Not the answer for the above problem but on the similar lines   Program to  print the elements of the array sequentially but use two different threads to print the adjacent elements  import java util logging Level  import java util logging Logger              author ntv     public class PrintLAternateNumber       public static void main String   args            int    num    1 2 3 4 5 6           Printer p   new Printer            Thread t1   new Thread new Thread1 num   p    Thread1            Thread t2   new Thread new Thread2 num   p    Thread2            t1 start            t2 start               class Thread1 implements Runnable       int    num      Printer p       public Thread1 int   num   Printer p            this num   num          this p   p             public void run             try               print              catch  InterruptedException ex                Logger getLogger Thread1 class getName    log Level SEVERE  null  ex                        public void print   throws InterruptedException           int i   1               while i  lt  num length                    synchronized num                        while  p evenPrinted                            num wait                                                                 synchronized num                         p printEven Thread currentThread   getName    num i                         i  i   2                       num notifyAll                                               class Thread2 implements Runnable       int    num      Printer p       public Thread2 int   num  Printer p            this num   num          this p   p             public void run             try               print              catch  InterruptedException ex                Logger getLogger Thread2 class getName    log Level SEVERE  null  ex                        public void print   throws InterruptedException           int i   0               while i  lt  num length                    synchronized num                        while   p evenPrinted                            num wait                                                                   synchronized num                         p printOdd Thread currentThread   getName    num i                         i   i   2                       num notifyAll                                              class Printer       boolean evenPrinted   true      void printEven String threadName   int i            System out println threadName         i           evenPrinted   true                  void printOdd String threadName   int i            System out println threadName         i           evenPrinted   false

[java] Create two threads, one display odd & other even numbers

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