#502 Replaced usages of System.out with logger.

async-method-invocation/src/main/java/com/iluwatar/async/method/invocation/App.java

@@ -22,6 +22,9 @@
  */
 package com.iluwatar.async.method.invocation;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import java.util.concurrent.Callable;
 
 /**
@@ -54,6 +57,8 @@ import java.util.concurrent.Callable;
  */
 public class App {
 
+  private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
+
   /**
    * Program entry point
    */
@@ -120,6 +125,6 @@ public class App {
   }
 
   private static void log(String msg) {
-    System.out.println(String.format("[%1$-10s] - %2$s", Thread.currentThread().getName(), msg));
+    LOGGER.info(msg);
   }
 }