Printing Even and Odd using two Threads in Java

Question

I tried the code below. I took this piece of code from some other post which is correct as per the author. But when I try running, it doesn't give me the exact result.

This is mainly to print even and odd values in sequence.

public class PrintEvenOddTester {        public static void main(String ... args){         Printer print = new Printer(false);         Thread t1 = new Thread(new TaskEvenOdd(print));         Thread t2 = new Thread(new TaskEvenOdd(print));         t1.start();         t2.start();     }   }    class TaskEvenOdd implements Runnable {      int number=1;     Printer print;      TaskEvenOdd(Printer print){         this.print = print;     }      @Override     public void run() {          System.out.println("Run method");         while(number<10){              if(number%2 == 0){                 System.out.println("Number is :"+ number);                 print.printEven(number);                 number+=2;             }             else {                 System.out.println("Number is :"+ number);                 print.printOdd(number);                 number+=2;             }         }        }      }  class Printer {      boolean isOdd;      Printer(boolean isOdd){         this.isOdd = isOdd;     }      synchronized void printEven(int number) {          while(isOdd){             try {                 wait();             } catch (InterruptedException e) {                 e.printStackTrace();             }         }         System.out.println("Even:"+number);         isOdd = true;         notifyAll();     }      synchronized void printOdd(int number) {         while(!isOdd){             try {                 wait();             } catch (InterruptedException e) {                 e.printStackTrace();             }         }         System.out.println("Odd:"+number);         isOdd = false;         notifyAll();     }  } 

Can someone help me in fixing this?

EDIT Expected result: Odd:1 Even:2 Odd:3 Even:4 Odd:5 Even:6 Odd:7 Even:8 Odd:9

Answer 1

Found the solution. Someone looking for solution to this problem can refer :-)

public class PrintEvenOddTester {      public static void main(String... args) {         Printer print = new Printer();         Thread t1 = new Thread(new TaskEvenOdd(print, 10, false));         Thread t2 = new Thread(new TaskEvenOdd(print, 10, true));         t1.start();         t2.start();     }  }  class TaskEvenOdd implements Runnable {      private int max;     private Printer print;     private boolean isEvenNumber;      TaskEvenOdd(Printer print, int max, boolean isEvenNumber) {         this.print = print;         this.max = max;         this.isEvenNumber = isEvenNumber;     }      @Override     public void run() {          //System.out.println("Run method");         int number = isEvenNumber == true ? 2 : 1;         while (number <= max) {              if (isEvenNumber) {                 //System.out.println("Even :"+ Thread.currentThread().getName());                 print.printEven(number);                 //number+=2;             } else {                 //System.out.println("Odd :"+ Thread.currentThread().getName());                 print.printOdd(number);                 // number+=2;             }             number += 2;         }      }  }  class Printer {      boolean isOdd = false;      synchronized void printEven(int number) {          while (isOdd == false) {             try {                 wait();             } catch (InterruptedException e) {                 e.printStackTrace();             }         }         System.out.println("Even:" + number);         isOdd = false;         notifyAll();     }      synchronized void printOdd(int number) {         while (isOdd == true) {             try {                 wait();             } catch (InterruptedException e) {                 e.printStackTrace();             }         }         System.out.println("Odd:" + number);         isOdd = true;         notifyAll();     }  } 

This gives output like:

Odd:1 Even:2 Odd:3 Even:4 Odd:5 Even:6 Odd:7 Even:8 Odd:9 Even:10 

Answer 2

Use this following very simple JAVA 8 Runnable Class feature

public class MultiThreadExample {  static AtomicInteger atomicNumber = new AtomicInteger(1);  public static void main(String[] args) {     Runnable print = () -> {         while (atomicNumber.get() < 10) {             synchronized (atomicNumber) {                 if ((atomicNumber.get() % 2 == 0) && "Even".equals(Thread.currentThread().getName())) {                     System.out.println("Even" + ":" + atomicNumber.getAndIncrement());                 } //else if ((atomicNumber.get() % 2 != 0) && "Odd".equals(Thread.currentThread().getName()))                    else {System.out.println("Odd" + ":" + atomicNumber.getAndIncrement());                 }             }         }     };      Thread t1 = new Thread(print);     t1.setName("Even");     t1.start();     Thread t2 = new Thread(print);     t2.setName("Odd");     t2.start();  } }