updated README.MD

join/README.md

@@ -47,26 +47,15 @@ import lombok.extern.slf4j.Slf4j;
  * main thread will continue when CountDownLatch count becomes 0 
  * CountDownLatch will start with count 4 and 4 demo threads will decrease it by 1 
  * everytime when they will finish .
+ * DemoThreads are implemented in join pattern such that every newly created thread 
+ * waits for the completion of previous thread by previous.join() . Hence maintaining 
+ * execution order of demo threads .
+ * JoinPattern object ensures that dependent threads execute only after completion of
+ * demo threads by pattern.await() . This method keep the main thread in waiting state
+ * until countdown latch becomes 0 . CountdownLatch will become 0 as all demo threads 
+ * will be completed as each of them have decreased it by 1 and its initial count was set to noOfDemoThreads.
+ * Hence this pattern ensures dependent threads will start only after completion of demo threads .
  */
-
-@Slf4j
-public class JoinPatternDemo {
-
-  /**
-   * execution of demo and dependent threads. 
-   */
-  public static void main(String[] args) {
-
-    int[] executionOrder = {4, 2, 1, 3};
-    int noOfDemoThreads = 4;
-    int noOfDependentThreads = 2;
-    JoinPattern pattern = new JoinPattern(noOfDemoThreads, executionOrder);
-    Thread previous = null;
-
-    for (int i = 0; i < noOfDemoThreads; i++) {
-      previous = new Thread(new DemoThread(executionOrder[i], previous));
-      previous.start();
-    }
     pattern.await();
 
     //Dependent threads after execution of DemoThreads
@@ -75,25 +64,43 @@ public class JoinPatternDemo {
     }
     LOGGER.info("end of program ");
 
-  }
+    /**
+   * use to run demo thread.
+   * every newly created thread waits for 
+   * the completion of previous thread 
+   * by previous.join() .
+   */
+  @Override
+  public void run() {
+    if (previous != null) {
+      try {
+        previous.join();
+      } catch (InterruptedException e) {
+        Thread.currentThread().interrupt();
+        LOGGER.error("Interrupted exception : ", e);
+      }
+    }
 
-}
 
 ```
 
 ### Program Output:
 
-```
-Running com.iluwatar.join.JoinPatternTest
-01:13:17.890 [Thread-2] INFO com.iluwatar.join.DemoThread -- Thread 1 starts
-01:13:18.167 [Thread-2] INFO com.iluwatar.join.DemoThread -- Thread 1 ends
-01:13:18.168 [Thread-3] INFO com.iluwatar.join.DemoThread -- Thread 4 starts
-01:13:19.176 [Thread-3] INFO com.iluwatar.join.DemoThread -- Thread 4 ends
-01:13:19.176 [Thread-4] INFO com.iluwatar.join.DemoThread -- Thread 3 starts
-01:13:19.935 [Thread-4] INFO com.iluwatar.join.DemoThread -- Thread 3 ends
-01:13:19.935 [Thread-5] INFO com.iluwatar.join.DemoThread -- Thread 2 starts
-01:13:20.437 [Thread-5] INFO com.iluwatar.join.DemoThread -- Thread 2 ends
-```
+[INFO] Running com.iluwatar.join.JoinPatternTest
+16:12:01.815 [Thread-2] INFO com.iluwatar.join.DemoThread -- Thread 1 starts
+16:12:02.086 [Thread-2] INFO com.iluwatar.join.DemoThread -- Thread 1 ends
+16:12:02.087 [Thread-3] INFO com.iluwatar.join.DemoThread -- Thread 4 starts
+16:12:03.090 [Thread-3] INFO com.iluwatar.join.DemoThread -- Thread 4 ends
+16:12:03.091 [Thread-4] INFO com.iluwatar.join.DemoThread -- Thread 3 starts
+16:12:03.851 [Thread-4] INFO com.iluwatar.join.DemoThread -- Thread 3 ends
+16:12:03.851 [Thread-5] INFO com.iluwatar.join.DemoThread -- Thread 2 starts
+16:12:04.352 [Thread-5] INFO com.iluwatar.join.DemoThread -- Thread 2 ends
+[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 2.904 s -- in com.iluwatar.join.JoinPatternTest
+[INFO] 
+[INFO] Results:
+[INFO]
+[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
+[INFO]
 
 ## When to Use the Join Pattern in Java
 

join/src/main/java/com/iluwatar/join/DemoThread.java

@@ -32,15 +32,14 @@
 @Slf4j
 public class DemoThread implements Runnable {
 
-  private static int[] executionOrder;
   private static int[] actualExecutionOrder;
   private static int index = 0;
   private static JoinPattern pattern;
-  private int id;
-  private Thread previous;
+  private final int id;
+  private final Thread previous;
 
   /**
-   * Initalise a demo thread object with id and previous thread .
+   * Initialise a demo thread object with id and previous thread .
    */
   public DemoThread(int id, Thread previous) {
     this.id = id;
@@ -55,26 +54,31 @@ public static int[] getActualExecutionOrder() {
    * set custom execution order of threads .
    */
   public static void setExecutionOrder(int[] executionOrder, JoinPattern pattern) {
-    DemoThread.executionOrder = executionOrder;
     DemoThread.pattern = pattern;
     actualExecutionOrder = new int[executionOrder.length];
   }
   /**
    * use to run demo thread.
+   * every newly created thread waits for 
+   * the completion of previous thread 
+   * by previous.join() .
    */
+  @Override
   public void run() {
     if (previous != null) {
       try {
         previous.join();
       } catch (InterruptedException e) {
-        e.printStackTrace();
+        Thread.currentThread().interrupt();
+        LOGGER.error("Interrupted exception : ", e);
       }
     }
     LOGGER.info("Thread " + id + " starts");
     try {
-      Thread.sleep(id * 250);
+      Thread.sleep(id * (long) 250);
     } catch (InterruptedException e) {
-      e.printStackTrace();
+      Thread.currentThread().interrupt();
+      LOGGER.error("Interrupted exception : ", e);
     } finally {
       LOGGER.info("Thread " + id + " ends");
       actualExecutionOrder[index++] = id;

join/src/main/java/com/iluwatar/join/DependentThread.java

@@ -24,8 +24,6 @@
  */
 package com.iluwatar.join;
 
-import lombok.Getter;
-import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 
 /**
@@ -34,21 +32,22 @@
 @Slf4j
 public class DependentThread implements Runnable {
 
-
-  private int id;
+  private final int id;
   DependentThread(int id) {
     this.id = id;
   }
   /**
    * dependent threads run .
    */
+  @Override
   public void run() {
 
     LOGGER.info(" Dependent Thread " + id + " starts ");
     try {
-      Thread.sleep(id * 200);
+      Thread.sleep(id * (long) 200);
     } catch (InterruptedException e) {
-      e.printStackTrace();
+      Thread.currentThread().interrupt();
+      LOGGER.error("Interrupted exception : ", e);
     } finally {
       LOGGER.info("Dependent Thread " + id + " completed ");
     }

join/src/main/java/com/iluwatar/join/JoinPatternDemo.java

@@ -30,6 +30,14 @@
  * main thread will continue when CountDownLatch count becomes 0 
  * CountDownLatch will start with count 4 and 4 demo threads will decrease it by 1 
  * everytime when they will finish .
+ * DemoThreads are implemented in join pattern such that every newly created thread 
+ * waits for the completion of previous thread by previous.join() . Hence maintaining 
+ * execution order of demo threads .
+ * JoinPattern object ensures that dependent threads execute only after completion 
+ * demo threads by pattern.await() . This method keep the main thread in waiting state
+ * until countdown latch becomes 0 . CountdownLatch will become 0 as all demo threads 
+ * will be completed as each of them have decreased it by 1 and its initial count was set to noOfDemoThreads.
+ * Hence this pattern ensures dependent threads will start only after completion of demo threads .
  */
 
 @Slf4j