#502 Replaced usages of System.out with logger.

half-sync-half-async/src/main/java/com/iluwatar/halfsynchalfasync/App.java

@@ -22,6 +22,9 @@
  */
 package com.iluwatar.halfsynchalfasync;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import java.util.concurrent.LinkedBlockingQueue;
 
 /**
@@ -66,6 +69,8 @@ import java.util.concurrent.LinkedBlockingQueue;
  */
 public class App {
 
+  private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
+
   /**
    * Program entry point
    * 
@@ -128,7 +133,7 @@ public class App {
     @Override
     public void onPostCall(Long result) {
       // Handle the result of computation
-      System.out.println(result);
+      LOGGER.info(result.toString());
     }
 
     @Override
@@ -141,7 +146,7 @@ public class App {
     try {
       Thread.sleep(i);
     } catch (InterruptedException e) {
-      System.out.println(e);
+      LOGGER.error("Exception caught.", e);
     }
     return i * (i + 1) / 2;
   }