printing alternatively

Author: Arjiit

concurrency/fooBarAlternate.java

@@ -0,0 +1,31 @@
+import java.util.concurrent.*;
+class FooBar {
+    private int n;
+    Semaphore s, a;
+    public FooBar(int n) {
+        this.n = n;
+        s = new Semaphore(1);
+        a = new Semaphore(0);
+    }
+
+    public void foo(Runnable printFoo) throws InterruptedException {
+        
+        for (int i = 0; i < n; i++) {
+            
+        	// printFoo.run() outputs "foo". Do not change or remove this line.
+            s.acquire();
+        	printFoo.run();
+            a.release();
+        }
+    }
+
+    public void bar(Runnable printBar) throws InterruptedException {
+        
+        for (int i = 0; i < n; i++) {
+            a.acquire();
+            // printBar.run() outputs "bar". Do not change or remove this line.
+        	printBar.run();
+            s.release();
+        }
+    }
+}