From 30df34ebacf0328670d3a9d58d69667c0f6d2cb0 Mon Sep 17 00:00:00 2001
From: "Begerad, Stefan" <dialog@swingbe.de>
Date: Thu, 24 Feb 2022 05:09:36 -0500
Subject: [PATCH] feat(ses): add scheduled-executor-service

---
 scheduled-executor-service/README.md          |  6 ++
 scheduled-executor-service/pom.xml            | 86 +++++++++++++++++++
 .../src/main/java/de/swingbe/ses/Main.java    | 61 +++++++++++++
 3 files changed, 153 insertions(+)
 create mode 100644 scheduled-executor-service/README.md
 create mode 100644 scheduled-executor-service/pom.xml
 create mode 100644 scheduled-executor-service/src/main/java/de/swingbe/ses/Main.java

diff --git a/scheduled-executor-service/README.md b/scheduled-executor-service/README.md
new file mode 100644
index 0000000..57fa48d
--- /dev/null
+++ b/scheduled-executor-service/README.md
@@ -0,0 +1,6 @@
+# Overview
+This project can serve as example for asynchronous task scheduling with Maven and Java.
+
+# Links
+[Generating random numbers in Java](https://www.geeksforgeeks.org/generating-random-numbers-in-java/)
+[https://www.geeksforgeeks.org/generating-random-numbers-in-java/](https://www.geeksforgeeks.org/scheduledexecutorservice-interface-in-java/)
diff --git a/scheduled-executor-service/pom.xml b/scheduled-executor-service/pom.xml
new file mode 100644
index 0000000..0dc5462
--- /dev/null
+++ b/scheduled-executor-service/pom.xml
@@ -0,0 +1,86 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xmlns="http://maven.apache.org/POM/4.0.0"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <name>ses</name>
+    <description>description</description>
+    <url>https://swingbe.de</url>
+    <groupId>de.swingbe</groupId>
+    <artifactId>ses</artifactId>
+    <version>0.0.1</version>
+    <packaging>jar</packaging>
+
+    <licenses>
+        <license>
+            <name>GNU General Public License</name>
+            <url>https://www.gnu.org/licenses/gpl-3.0.txt</url>
+        </license>
+    </licenses>
+
+    <scm>
+        <url>https://github.com/Software-Ingenieur-Begerad/sandbox-java</url>
+    </scm>
+
+    <properties>
+        <!-- Other properties -->
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>3.8.1</version>
+                <configuration>
+                    <!-- Target Java versions -->
+                    <release>11</release>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-shade-plugin</artifactId>
+                <version>3.2.1</version>
+                <executions>
+                    <execution>
+                        <phase>package</phase>
+                        <goals>
+                            <goal>shade</goal>
+                        </goals>
+                        <configuration>
+                            <filters>
+                                <filter>
+                                    <!-- exclude signatures from merged JAR to avoid invalid signature messages -->
+                                    <artifact>*:*</artifact>
+                                    <excludes>
+                                        <exclude>META-INF/*.SF</exclude>
+                                        <exclude>META-INF/*.DSA</exclude>
+                                        <exclude>META-INF/*.RSA</exclude>
+                                    </excludes>
+                                </filter>
+                            </filters>
+                            <!-- The shaded JAR will not be the main artifact for the project, it will be attached
+                              for deployment in the way source and docs are. -->
+                            <shadedArtifactAttached>true
+                            </shadedArtifactAttached>
+                            <shadedClassifierName>shaded</shadedClassifierName>
+                            <transformers>
+                                <transformer
+                                        implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer"/>
+                                <transformer
+                                        implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
+                                    <manifestEntries>
+                                        <Main-Class>de.swingbe.ses.SchedulerExecutorServiceExample
+                                        </Main-Class>
+                                    </manifestEntries>
+                                </transformer>
+                            </transformers>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+</project>
diff --git a/scheduled-executor-service/src/main/java/de/swingbe/ses/Main.java b/scheduled-executor-service/src/main/java/de/swingbe/ses/Main.java
new file mode 100644
index 0000000..7ef0d1f
--- /dev/null
+++ b/scheduled-executor-service/src/main/java/de/swingbe/ses/Main.java
@@ -0,0 +1,61 @@
+package de.swingbe.ses;
+
+import java.util.concurrent.*;
+import java.util.*;
+
+//System.out.println();
+import java.io.*;
+  
+class SchedulerExecutorServiceExample {
+    
+    public static void main(String[] args)
+    {
+        System.out.println(
+            "A count-down-clock program that counts from 10 to 0");
+  
+        // creating a ScheduledExecutorService object
+        ScheduledExecutorService scheduler
+            = Executors.newScheduledThreadPool(11);
+  
+        // printing the current time
+        System.out.println(
+            "Current time : "
+            + Calendar.getInstance().get(Calendar.SECOND));
+  
+        // Scheduling the tasks
+        for (int i = 10; i >= 0; i--) {
+            scheduler.schedule(new Task(i), 10 - i,
+                               TimeUnit.SECONDS);
+        }
+  
+        // remember to shutdown the scheduler
+        // so that it no longer accepts
+          // any new tasks
+        scheduler.shutdown();
+    }
+}
+  
+class Task implements Runnable {
+    private int num;
+    public Task(int num) { this.num = num; }
+    public void run()
+    {
+	if(num%1==0){
+	    // create instance of Random class
+	    Random rand = new Random();
+	    // Generate random integers in range 0 to 1999
+	    int randInt = rand.nextInt(2000);
+	    
+	    System.out.println("num: " +num+", rand: " + randInt);
+	    try {
+		Thread.sleep(randInt);
+            } catch (InterruptedException e) {
+                System.out.println("Another thread has interrupted this one, message: " + e.getMessage() + ", trace: " + e.getStackTrace());
+            }
+	    System.out.println("num: "+num+", sleep() done.");
+	}
+        System.out.println(
+            "num: " + num + " Current time : "
+            + Calendar.getInstance().get(Calendar.SECOND));
+    }
+}