René's URL Explorer Experiment

{"@context":"https://schema.org","@graph":[{"@type":"Article","@id":"https://examples.javacodegeeks.com/java-development/core-java/util/timer-util/java-timer-example/#article","isPartOf":{"@id":"https://examples.javacodegeeks.com/java-development/core-java/util/timer-util/java-timer-example/"},"author":{"name":"Vishal Rajpal","@id":"https://examples.javacodegeeks.com/#/schema/person/12ed9c93288f688dbdbdcb1c46063530"},"headline":"Java Timer example","datePublished":"2014-06-16T18:34:30+00:00","dateModified":"2014-06-16T21:12:11+00:00","mainEntityOfPage":{"@id":"https://examples.javacodegeeks.com/java-development/core-java/util/timer-util/java-timer-example/"},"wordCount":622,"commentCount":0,"publisher":{"@id":"https://examples.javacodegeeks.com/#organization"},"image":{"@id":"https://examples.javacodegeeks.com/java-development/core-java/util/timer-util/java-timer-example/#primaryimage"},"thumbnailUrl":"https://examples.javacodegeeks.com/wp-content/uploads/2012/12/java-logo.jpg","keywords":["ScheduledThreadPoolExecutor","TimerTask"],"articleSection":["Timer"],"inLanguage":"en-US","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https://examples.javacodegeeks.com/java-development/core-java/util/timer-util/java-timer-example/#respond"]}]},{"@type":"WebPage","@id":"https://examples.javacodegeeks.com/java-development/core-java/util/timer-util/java-timer-example/","url":"https://examples.javacodegeeks.com/java-development/core-java/util/timer-util/java-timer-example/","name":"Java Timer example - Java Code Geeks","isPartOf":{"@id":"https://examples.javacodegeeks.com/#website"},"primaryImageOfPage":{"@id":"https://examples.javacodegeeks.com/java-development/core-java/util/timer-util/java-timer-example/#primaryimage"},"image":{"@id":"https://examples.javacodegeeks.com/java-development/core-java/util/timer-util/java-timer-example/#primaryimage"},"thumbnailUrl":"https://examples.javacodegeeks.com/wp-content/uploads/2012/12/java-logo.jpg","datePublished":"2014-06-16T18:34:30+00:00","dateModified":"2014-06-16T21:12:11+00:00","description":"In this example, we will learn about the Timer class available under the java.util package. The Timer facilitates the execution of tasks in a background","breadcrumb":{"@id":"https://examples.javacodegeeks.com/java-development/core-java/util/timer-util/java-timer-example/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https://examples.javacodegeeks.com/java-development/core-java/util/timer-util/java-timer-example/"]}]},{"@type":"ImageObject","inLanguage":"en-US","@id":"https://examples.javacodegeeks.com/java-development/core-java/util/timer-util/java-timer-example/#primaryimage","url":"https://examples.javacodegeeks.com/wp-content/uploads/2012/12/java-logo.jpg","contentUrl":"https://examples.javacodegeeks.com/wp-content/uploads/2012/12/java-logo.jpg","width":150,"height":150,"caption":"Bipartite Graph"},{"@type":"BreadcrumbList","@id":"https://examples.javacodegeeks.com/java-development/core-java/util/timer-util/java-timer-example/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://examples.javacodegeeks.com/"},{"@type":"ListItem","position":2,"name":"Java Development","item":"https://examples.javacodegeeks.com/category/java-development/"},{"@type":"ListItem","position":3,"name":"Core Java","item":"https://examples.javacodegeeks.com/category/java-development/core-java/"},{"@type":"ListItem","position":4,"name":"util","item":"https://examples.javacodegeeks.com/category/java-development/core-java/util/"},{"@type":"ListItem","position":5,"name":"Timer","item":"https://examples.javacodegeeks.com/category/java-development/core-java/util/timer-util/"},{"@type":"ListItem","position":6,"name":"Java Timer example"}]},{"@type":"WebSite","@id":"https://examples.javacodegeeks.com/#website","url":"https://examples.javacodegeeks.com/","name":"Java Code Geeks","description":"Java Examples and Code Snippets","publisher":{"@id":"https://examples.javacodegeeks.com/#organization"},"alternateName":"JCG","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://examples.javacodegeeks.com/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Organization","@id":"https://examples.javacodegeeks.com/#organization","name":"Exelixis Media P.C.","url":"https://examples.javacodegeeks.com/","logo":{"@type":"ImageObject","inLanguage":"en-US","@id":"https://examples.javacodegeeks.com/#/schema/logo/image/","url":"https://examples.javacodegeeks.com/wp-content/uploads/2022/06/exelixis-logo.png","contentUrl":"https://examples.javacodegeeks.com/wp-content/uploads/2022/06/exelixis-logo.png","width":864,"height":246,"caption":"Exelixis Media P.C."},"image":{"@id":"https://examples.javacodegeeks.com/#/schema/logo/image/"},"sameAs":["https://www.facebook.com/javacodegeeks","https://x.com/javacodegeeks"]},{"@type":"Person","@id":"https://examples.javacodegeeks.com/#/schema/person/12ed9c93288f688dbdbdcb1c46063530","name":"Vishal Rajpal","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https://examples.javacodegeeks.com/#/schema/person/image/","url":"https://examples.javacodegeeks.com/wp-content/uploads/2014/06/Vishal-Rajpal-96x96.jpg","contentUrl":"https://examples.javacodegeeks.com/wp-content/uploads/2014/06/Vishal-Rajpal-96x96.jpg","caption":"Vishal Rajpal"},"description":"Vishal enjoys designing and developing small and mid-sized Enterprise solutions in Java and it's ecosystem. He has graduated from RGTU, India in Electronics and Telecommunication Engineering. Currently, Vishal is working with an Analytics organization, enabling the in-house analytics as well as client teams to use technology as a differentiator for projects / problems related to Big Data.","sameAs":["http://www.javacodegeeks.com/"],"url":"https://examples.javacodegeeks.com/author/vishal-rajpal/"}]}

{"@context":"http:\/\/schema.org","@type":"BreadcrumbList","@id":"#Breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"item":{"name":"Home","@id":"https:\/\/examples.javacodegeeks.com\/"}},{"@type":"ListItem","position":2,"item":{"name":"Java Development","@id":"https:\/\/examples.javacodegeeks.com\/category\/java-development\/"}},{"@type":"ListItem","position":3,"item":{"name":"Core Java","@id":"https:\/\/examples.javacodegeeks.com\/category\/java-development\/core-java\/"}},{"@type":"ListItem","position":4,"item":{"name":"util","@id":"https:\/\/examples.javacodegeeks.com\/category\/java-development\/core-java\/util\/"}},{"@type":"ListItem","position":5,"item":{"name":"Timer","@id":"https:\/\/examples.javacodegeeks.com\/category\/java-development\/core-java\/util\/timer-util\/"}}]}

{"@context":"http:\/\/schema.org","@type":"Article","dateCreated":"2014-06-16T21:34:30+03:00","datePublished":"2014-06-16T21:34:30+03:00","dateModified":"2014-06-17T00:12:11+03:00","headline":"Java Timer example","name":"Java Timer example","keywords":"ScheduledThreadPoolExecutor,TimerTask","url":"https:\/\/examples.javacodegeeks.com\/java-development\/core-java\/util\/timer-util\/java-timer-example\/","description":"In this example, we will learn about the Timer class available under the java.util package. The Timer facilitates the execution of tasks in a background thread. The tasks to be executed by the Timer c","copyrightYear":"2014","articleSection":"Timer","articleBody":"In this example, we will learn about the Timer class available under the java.util package.\r\n\r\nThe Timer facilitates the execution of tasks in a background thread. The tasks to be executed by the Timer can be chosen either to be a one-time execution OR a repeated execution at pre-defined intervals.\r\n\r\nAlong with the mentioned execution frequency of the task, the scheduling time \/ delay of these tasks can also be optionally mentioned to the Timer class.\r\n\r\nRepresenting what is stated above, the TimerTask to be executed can be:\r\n\r\n\tOne-time execution which in turn can be:\r\n\r\n\tScheduled immediately\r\n\tScheduled to start after a delay\r\n\r\n\r\n\tRepeated execution at regular intervals which in turn can be:\r\n\r\n\tScheduled immediately\r\n\tScheduled to start after a delay\r\n\r\n\r\n\r\nComponents of Timer\r\nWe would briefly look at the internal components of the Timer class. In terms of usage, one only needs to create Tasks by extending the TimerTask and schedule them with the Timer instance.\r\n\r\nThe other two internal components - TaskQueue and TimerThread have been mentioned below for information purpose, so as to help one evaluate when and for what kind of tasks should the Timer class be used.\r\n\r\n\r\nTask Queue\r\n\r\nInternally, the Timer uses the TaskQueue as a \"priority\" queue maintaining tasks in the order of next execution. The priority queue holds task in the sequence they should be executed by the TimerThread.\r\n\r\nTimer Thread\r\nThe TimerThread is a thread helper class which repeatedly monitors the TaskQueue and \"sequentially\" executes the tasks based on their execution order and time of execution. To note here, the Timer has only one instance of the TimerThread internally. Thus, if any of the scheduled Timer tasks takes excessive time to run, the other tasks scheduled for execution will keep waiting till the offending task completes. The waiting tasks may then be executed in rapid successions by the TimerThread causing unexpected results.\r\n\r\nTimer Task\r\nThe TimerTask is the actual unit of task that needs to be performed by the Timer for either once or multiple times at regular intervals. The TimerTask is an abstract class implementing Runnable. As a user of the Timer, one needs to extend this class and implement the run method by providing the logic of the task that needs to be performed.\r\n\r\nNow, let us look at an example using the Timer. In the example, we create two TimerTask:\r\n\r\n\tA TimerTask in a slave node which sends some heart-beat information at an interval of 10 seconds. The task is scheduled to start with a delay of 1 second.\r\n\tA TimerTask which updates the status being sent by the first task to AMBER. This task is executed once after a delay of 30 seconds.\r\n\r\nLet's look at TimerTask #1, TimerTaskSendHeartBeat for heartbeat sending.\r\nclass TimerTaskSendHeartBeat extends TimerTask {\r\n\r\n\tTimerExample healthStatusHolder = null;\r\n\r\n\tpublic TimerTaskSendHeartBeat(TimerExample healthStatusHolder) {\r\n\t\tthis.healthStatusHolder = healthStatusHolder;\r\n\t}\r\n\r\n\tHeartBeatMessage message = null;\r\n\r\n\t@Override\r\n\tpublic void run() {\r\n\r\n\t\t\/\/ create HeartBeat message by getting Health Status (RED\/GREEN\/AMBER)\r\n\t\t\/\/ Error Code, if any AND time at which heartbeat is sent to help\r\n\t\t\/\/ receiver discard any delayed messages due to latency\r\n\t\tmessage = new HeartBeatMessage(\r\n\t\t\t\tthis.healthStatusHolder.getHealthStatus(), Calendar\r\n\t\t\t\t\t\t.getInstance().getTimeInMillis(), -1);\r\n\r\n\t\tSystem.out.println(\"Sending HeartBeat Message\");\r\n\r\n\t\t\/\/ Send the message to Monitoring Dashboard\r\n\t\tSystem.out.println(message);\r\n\r\n\t\tSystem.out.println(\"HeartBeat Message Sent\");\r\n\t}\r\n\r\n\t\/**\r\n\t * Simple POJO which is a heartbeat message object It can have any decoder\r\n\t * encoder mechanism to send over any messaging platform\r\n\t *\/\r\n\tclass HeartBeatMessage {\r\n\t\tprivate String status;\r\n\t\tprivate long heartBeatTime;\r\n\t\tprivate int errorCode;\r\n\r\n\t\tpublic HeartBeatMessage(String status, long heartBeatTime, int errorCode) {\r\n\t\t\tthis.status = status;\r\n\t\t\tthis.heartBeatTime = heartBeatTime;\r\n\t\t\tthis.errorCode = errorCode;\r\n\t\t}\r\n\r\n\t\tpublic String getStatus() {\r\n\t\t\treturn status;\r\n\t\t}\r\n\r\n\t\tpublic long getHeartBeatTime() {\r\n\t\t\treturn heartBeatTime;\r\n\t\t}\r\n\r\n\t\tpublic int getErrorCode() {\r\n\t\t\treturn errorCode;\r\n\t\t}\r\n\r\n\t\t@Override\r\n\t\tpublic String toString() {\r\n\t\t\treturn \"status: \" + status + \" timeOfHeartBeat: \"\r\n\t\t\t\t\t+ new java.util.Date(this.heartBeatTime) + \" errCode : \"\r\n\t\t\t\t\t+ this.errorCode;\r\n\t\t}\r\n\t}\r\n\r\nBelow is the implementation of the TimerTask # 2, TimerTaskUpdateHeartBeat which just updates the status of the heartbeat message being sent.\r\n\r\nclass TimerTaskUpdateHeartBeat extends TimerTask {\r\n\r\n\tTimerExample healthClass = null;\r\n\r\n\tpublic TimerTaskUpdateHeartBeat(TimerExample healthClass) {\r\n\t\tthis.healthClass = healthClass;\r\n\t}\r\n\r\n\t@Override\r\n\tpublic void run() {\r\n\t\tSystem.out.println(\"Task 2:: 30 seconds completed :: Updating health \"\r\n\t\t\t\t+ \"status to AMBER\");\r\n\t\thealthClass.setHealthStatus(\"AMBER\");\r\n\t}\r\n\r\n}\r\n\r\nOnce both the TimerTask have been created, let us know schedule the tasks at the desired time and frequency of execution. This would require creating a new Timer instance and scheduling tasks to it.\r\npublic class TimerExample {\r\n\tprivate String healthStatus = \"GREEN\";\r\n\r\n\tpublic static void main(String[] args) {\r\n\r\n\t\tTimerExample example = new TimerExample();\r\n\t\texample.setHealthStatus(\"GREEN\");\r\n\r\n\t\t\/\/ Create the Timer object\r\n\t\tTimer timer = new Timer(\"JCG Timer Example\");\r\n\r\n\t\t\/\/ Create Timer task created to send heartBeats\r\n\t\tTimerTask taskToExecute = new TimerTaskSendHeartBeat(example);\r\n\t\t\/\/ schedule the task to start executing after 1 second\r\n\t\t\/\/ and re-execute every 10 seconds\r\n\t\ttimer.scheduleAtFixedRate(taskToExecute, 1000, 10000);\r\n\r\n\t\t\/\/ Create Timer task to setHeartBeatStatus\r\n\t\tTimerTask setHeartBeatStatus = new TimerTaskUpdateHeartBeat(example);\r\n\t\t\/\/ schedule the task to start immediately but execute\r\n\t\t\/\/ first time after 30 seconds\r\n\t\ttimer.schedule(setHeartBeatStatus, 30000);\r\n\r\n\t\t\/\/ Wait for 60 seconds and then cancel the timer cleanly\r\n\t\ttry {\r\n\t\t\tThread.sleep(60000);\r\n\t\t} catch (InterruptedException e) {\r\n\t\t}\r\n\t\tSystem.out.println(\"Cancelling Timer Cleanly after 60 seconds\");\r\n\t\ttimer.cancel();\r\n\t}\r\n\r\n\t\/**\r\n\t * Get Heartbeat Status of the application, could be GREEN \/ AMBER \/ RED\r\n\t * based on any exceptions or service health\r\n\t * \r\n\t * @return String\r\n\t *\/\r\n\tpublic String getHealthStatus() {\r\n\t\treturn this.healthStatus;\r\n\t}\r\n\r\n\t\/**\r\n\t * Set the status for the application could be GREEN \/ AMBER \/ RED\r\n\t * \r\n\t * @param healthStatus\r\n\t *\/\r\n\tpublic void setHealthStatus(String healthStatus) {\r\n\t\tthis.healthStatus = healthStatus;\r\n\t}\r\n}\r\n\r\n\r\nOn execution of the program, the output looks as below:\r\n\r\nSending HeartBeat Message\r\nstatus: GREEN timeOfHeartBeat: Mon Jun 16 23:52:04 IST 2014 errCode : -1\r\nHeartBeat Message Sent\r\nSending HeartBeat Message\r\nstatus: GREEN timeOfHeartBeat: Mon Jun 16 23:52:14 IST 2014 errCode : -1\r\nHeartBeat Message Sent\r\nSending HeartBeat Message\r\nstatus: GREEN timeOfHeartBeat: Mon Jun 16 23:52:24 IST 2014 errCode : -1\r\nHeartBeat Message Sent\r\nTask 2:: 30 seconds completed :: Updating health status to AMBER\r\nSending HeartBeat Message\r\nstatus: AMBER timeOfHeartBeat: Mon Jun 16 23:52:34 IST 2014 errCode : -1\r\nHeartBeat Message Sent\r\nSending HeartBeat Message\r\nstatus: AMBER timeOfHeartBeat: Mon Jun 16 23:52:44 IST 2014 errCode : -1\r\nHeartBeat Message Sent\r\nSending HeartBeat Message\r\nstatus: AMBER timeOfHeartBeat: Mon Jun 16 23:52:54 IST 2014 errCode : -1\r\nHeartBeat Message Sent\r\nCancelling Timer Cleanly after 60 seconds\r\n\r\n\r\nAs seen from output above, the Timer is cancelled using the cancel method which ensures that any TimerTask being executed is completed before the Timer is cleaned up.\r\nOther Points about Timer\r\n\r\n\tThe Timer instance created can be instructed to start the TaskThread as a Daemon Thread, in case the thread should no longer exist if there are no non-daemon threads remaining in the VM.\r\n\tThe Timer is thread-safe and is internally synchronized.\r\n\tJava 5.0 introduced the ScheduledThreadPoolExecutor which is a thread pool for repeatedly executing tasks at a given rate or delay. It allows multiple service threads and accepts various time units. Thus, as the Timer has one single task execution thread (highlighted above), the ScheduledThreadPoolExecutor can have multiple threads executing\/dedicated to task execution, in turn preventing one faulty task causing other tasks to be waiting for thread resource for execution.\r\n\r\n\r\nThe source code is available for download here.","publisher":{"@id":"#Publisher","@type":"Organization","name":"Examples Java Code Geeks","logo":{"@type":"ImageObject","url":"\/wp-content\/uploads\/2013\/05\/JavaCodeGeeks-logo.png"},"sameAs":["https:\/\/feeds.feedburner.com\/examplesjavacodegeeks","https:\/\/www.facebook.com\/javacodegeeks","https:\/\/twitter.com\/javacodegeeks","https:\/\/www.linkedin.com\/groups\/3810709\/","https:\/\/www.youtube.com\/channel\/UCxoUc7Rar2q90Gu0nT2ffuQ","https:\/\/github.com\/javacodegeeks\/"]},"sourceOrganization":{"@id":"#Publisher"},"copyrightHolder":{"@id":"#Publisher"},"mainEntityOfPage":{"@type":"WebPage","@id":"https:\/\/examples.javacodegeeks.com\/java-development\/core-java\/util\/timer-util\/java-timer-example\/","breadcrumb":{"@id":"#Breadcrumb"}},"author":{"@type":"Person","name":"Vishal Rajpal","url":"https:\/\/examples.javacodegeeks.com\/author\/vishal-rajpal\/"},"image":{"@type":"ImageObject","url":"https:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2012\/12\/java-logo.jpg","width":1200,"height":150}}