Multiple threads odd-even refactor (#5617)

* encoding

* Converting synchronous and asynchronous API to observables

* Adding different ways of converting sync/async APIs to observalbles.

* Replace anonymous class with lambda

* update based on comment from Grzegorz Piwowarek

* Refactor even-odd semaphore demo

* Remove unrelated files

core-java-concurrency/src/main/java/com/baeldung/concurrent/evenandodd/PrintEvenOddSemaphore.java

@@ -2,55 +2,47 @@ package com.baeldung.concurrent.evenandodd;
 
 import java.util.concurrent.Semaphore;
 
-public class SemaphoreDemo {
+public class PrintEvenOddSemaphore {
 
     public static void main(String[] args) {
-
         SharedPrinter sp = new SharedPrinter();
-        Thread odd = new Thread(new Odd(sp, 10));
-        odd.setName("Odd");
-        Thread even = new Thread(new Even(sp, 10));
-        even.setName("Even");
+        Thread odd = new Thread(new Odd(sp, 10), "Odd");
+        Thread even = new Thread(new Even(sp, 10), "Even");
 
         odd.start();
         even.start();
-
     }
-
 }
 
 class SharedPrinter {
 
-    Semaphore semEven = new Semaphore(0);
-    Semaphore semOdd = new Semaphore(1);
+    private final Semaphore semEven = new Semaphore(0);
+    private final Semaphore semOdd = new Semaphore(1);
 
-    public void printEvenNum(int num) {
+    void printEvenNum(int num) {
         try {
             semEven.acquire();
         } catch (InterruptedException e) {
-            e.printStackTrace();
+            Thread.currentThread().interrupt();
         }
-        System.out.println(Thread.currentThread()
-            .getName() + ":"+num);
+        System.out.println(Thread.currentThread().getName() + ":"+num);
         semOdd.release();
     }
 
-    public void printOddNum(int num) {
+    void printOddNum(int num) {
         try {
             semOdd.acquire();
         } catch (InterruptedException e) {
-            e.printStackTrace();
+            Thread.currentThread().interrupt();
         }
-        System.out.println(Thread.currentThread()
-            .getName() + ":"+ num);
+        System.out.println(Thread.currentThread().getName() + ":"+ num);
         semEven.release();
-
     }
 }
 
 class Even implements Runnable {
-    SharedPrinter sp;
-    int max;
+    private final SharedPrinter sp;
+    private final int max;
 
     Even(SharedPrinter sp, int max) {
         this.sp = sp;
@@ -66,8 +58,8 @@ class Even implements Runnable {
 }
 
 class Odd implements Runnable {
-    SharedPrinter sp;
-    int max;
+    private SharedPrinter sp;
+    private int max;
 
     Odd(SharedPrinter sp, int max) {
         this.sp = sp;

core-java-concurrency/src/main/java/com/baeldung/concurrent/evenandodd/PrintEvenOddWaitNotify.java

@@ -1,22 +1,20 @@
 package com.baeldung.concurrent.evenandodd;
 
-public class PrintEvenOdd {
+public class PrintEvenOddWaitNotify {
 
     public static void main(String... args) {
         Printer print = new Printer();
-        Thread t1 = new Thread(new TaskEvenOdd(print, 10, false));
-        t1.setName("Odd");
-        Thread t2 = new Thread(new TaskEvenOdd(print, 10, true));
-        t2.setName("Even");
+        Thread t1 = new Thread(new TaskEvenOdd(print, 10, false), "Odd");
+        Thread t2 = new Thread(new TaskEvenOdd(print, 10, true), "Even");
         t1.start();
         t2.start();
     }
 }
 
 class TaskEvenOdd implements Runnable {
-    private int max;
-    private Printer print;
-    private boolean isEvenNumber;
+    private final int max;
+    private final Printer print;
+    private final boolean isEvenNumber;
 
     TaskEvenOdd(Printer print, int max, boolean isEvenNumber) {
         this.print = print;
@@ -26,7 +24,7 @@ class TaskEvenOdd implements Runnable {
 
     @Override
     public void run() {
-        int number = isEvenNumber == true ? 2 : 1;
+        int number = isEvenNumber ? 2 : 1;
         while (number <= max) {
             if (isEvenNumber) {
                 print.printEven(number);
@@ -39,32 +37,30 @@ class TaskEvenOdd implements Runnable {
 }
 
 class Printer {
-    boolean isOdd = false;
+    private volatile boolean isOdd;
 
     synchronized void printEven(int number) {
-        while (isOdd == false) {
+        while (!isOdd) {
             try {
                 wait();
             } catch (InterruptedException e) {
-                e.printStackTrace();
+                Thread.currentThread().interrupt();
             }
         }
-        System.out.println(Thread.currentThread()
-            .getName() + ":" + number);
+        System.out.println(Thread.currentThread().getName() + ":" + number);
         isOdd = false;
         notify();
     }
 
     synchronized void printOdd(int number) {
-        while (isOdd == true) {
+        while (isOdd) {
             try {
                 wait();
             } catch (InterruptedException e) {
-                e.printStackTrace();
+                Thread.currentThread().interrupt();
             }
         }
-        System.out.println(Thread.currentThread()
-            .getName() + ":" + number);
+        System.out.println(Thread.currentThread().getName() + ":" + number);
         isOdd = true;
         notify();
     }