From b49dd4f1ac66b46697fcd367bd572d48eca51fe3 Mon Sep 17 00:00:00 2001
From: Vaibhav Sahay <vsahay28@gmail.com>
Date: Fri, 2 Nov 2018 09:37:00 +0530
Subject: [PATCH] print odd and even using Semaphore

---
 .../concurrent/evenandodd/SemaphoreDemo.java  | 83 +++++++++++++++++++
 1 file changed, 83 insertions(+)
 create mode 100644 core-java-concurrency/src/main/java/com/baeldung/concurrent/evenandodd/SemaphoreDemo.java

diff --git a/core-java-concurrency/src/main/java/com/baeldung/concurrent/evenandodd/SemaphoreDemo.java b/core-java-concurrency/src/main/java/com/baeldung/concurrent/evenandodd/SemaphoreDemo.java
new file mode 100644
index 0000000000..c3afba1f68
--- /dev/null
+++ b/core-java-concurrency/src/main/java/com/baeldung/concurrent/evenandodd/SemaphoreDemo.java
@@ -0,0 +1,83 @@
+package com.baeldung.concurrent.evenandodd;
+
+import java.util.concurrent.Semaphore;
+
+public class SemaphoreDemo {
+
+    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");
+
+        odd.start();
+        even.start();
+
+    }
+
+}
+
+class SharedPrinter {
+
+    Semaphore semEven = new Semaphore(0);
+    Semaphore semOdd = new Semaphore(1);
+
+    public void printEvenNum(int num) {
+        try {
+            semEven.acquire();
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+        }
+        System.out.println(Thread.currentThread()
+            .getName() + ":"+num);
+        semOdd.release();
+    }
+
+    public void printOddNum(int num) {
+        try {
+            semOdd.acquire();
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+        }
+        System.out.println(Thread.currentThread()
+            .getName() + ":"+ num);
+        semEven.release();
+
+    }
+}
+
+class Even implements Runnable {
+    SharedPrinter sp;
+    int max;
+
+    Even(SharedPrinter sp, int max) {
+        this.sp = sp;
+        this.max = max;
+    }
+
+    @Override
+    public void run() {
+        for (int i = 2; i <= max; i = i + 2) {
+            sp.printEvenNum(i);
+        }
+    }
+}
+
+class Odd implements Runnable {
+    SharedPrinter sp;
+    int max;
+
+    Odd(SharedPrinter sp, int max) {
+        this.sp = sp;
+        this.max = max;
+    }
+
+    @Override
+    public void run() {
+        for (int i = 1; i <= max; i = i + 2) {
+            sp.printOddNum(i);
+        }
+    }
+}