Java Timer Class

Introduction

The Java Timer class provides facility for threads to schedule tasks for future execution in a background thread.

  • This class is thread-safe i.e multiple threads can share a single Timer object without the need for external synchronization.

  • This class schedules tasks for one-time execution, or for repeated execution at regular intervals.

  • All constructors start a timer thread.

Class declaration

Following is the declaration for java.util.Timer class −

public class Timer
   extends Object

Class constructors

Sr.No. Constructor & Description
1

Timer()

This constructor creates a new timer.
2

Timer(boolean isDaemon)

This constructor creates a new timer whose associated thread may be specified to run as a daemon.
3

Timer(String name)

This constructor creates a new timer whose associated thread has the specified name.
4

Timer(String name, boolean isDaemon)

This constructor creates a new timer whose associated thread has the specified name, and may be specified to run as a daemon.

Class methods

Sr.No. Method & Description
1 void cancel()

This method terminates this timer, discarding any currently scheduled tasks.
2 int purge()

This method removes all cancelled tasks from this timer's task queue.
3 void schedule(TimerTask task, Date time)

This method schedules the specified task for execution at the specified time.
4 void scheduleAtFixedRate(TimerTask task, Date firstTime, long period)

This method schedules the specified task for repeated fixed-rate execution, beginning at the specified time.

Methods inherited

This class inherits methods from the following classes −

  • java.util.Object

Scheduling a Task to Execute using Timer Example

The following example shows the usage of Java Timer schedule(TimerTask, Date) method to schedule a timer operation. We've created a timer object using a CustomTimerTask object. CustomTimerTask is custom class extending TimerTask class and implements the run() method which will execute at scheduled time. Then we created a timer object and scheduled a task using schedule() to execute task now.

package com.tutorialspoint;

import java.util.Date;
import java.util.Timer;
import java.util.TimerTask;

public class TimerDemo {
   public static void main(String[] args) {

      // creating timer task, timer
      TimerTask tasknew = new CustomTimerTask();
      Timer timer = new Timer("test",true);

      // scheduling the task
      timer.schedule(tasknew, new Date()); 

      try {
         Thread.sleep(1000);
      } catch (InterruptedException e) {
         System.out.println("Error");
      }
   }
}

class CustomTimerTask extends TimerTask {

   @Override
   public void run() {
      System.out.println("working on");
   }  
}

Output

Let us compile and run the above program, this will produce the following result.

working on
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