Timer in Java Thread

Question

I have a thread which is in charge of doing some processes. I want make it so that these processing would be done every 3 seconds. I've used the code below but when the thread starts, nothing happens. I assumed that when I define a task for my timer it automatically execute the ScheduledTask within time interval but it doesn't do anything at all. What am I missing?

class temperatureUp extends Thread  {     @Override     public void run()     {     TimerTask increaseTemperature = new TimerTask(){          public void run() {         try {             //do the processing          } catch (InterruptedException ex) {}         }     };      Timer increaserTimer = new Timer("MyTimer");     increaserTimer.schedule(increaseTemperature, 3000);      } }; 

Answer 1

A few errors in your code snippet:

• You extend the Thread class, which is not really good practice
• You have a Timer within a Thread? That doesnt make sense as the a Timer runs on its own Thread.

You should rather (when/where necessary), implement a Runnable see here for a short example, however I cannot see the need for both a Thread and Timer in the snippet you gave.

Please see the below example of a working Timer which will simply increment the counter by one each time it is called (every 3seconds):

import java.util.Timer; import java.util.TimerTask;  public class Test {      static int counter = 0;      public static void main(String[] args) {          TimerTask timerTask = new TimerTask() {              @Override             public void run() {                 System.out.println("TimerTask executing counter is: " + counter);                 counter++;//increments the counter             }         };          Timer timer = new Timer("MyTimer");//create a new Timer          timer.scheduleAtFixedRate(timerTask, 30, 3000);//this line starts the timer at the same time its executed     } } 

Addendum:

I did a short example of incorporating a Thread into the mix. So now the TimerTask will merely increment counter by 1 every 3 seconds, and the Thread will display counters value sleeping for 1 seconds every time it checks counter (it will terminate itself and the timer after counter==3):

import java.util.Timer; import java.util.TimerTask;  public class Test {      static int counter = 0;     static Timer timer;      public static void main(String[] args) {          //create timer task to increment counter         TimerTask timerTask = new TimerTask() {              @Override             public void run() {                 // System.out.println("TimerTask executing counter is: " + counter);                 counter++;             }         };          //create thread to print counter value         Thread t = new Thread(new Runnable() {              @Override             public void run() {                 while (true) {                     try {                         System.out.println("Thread reading counter is: " + counter);                         if (counter == 3) {                             System.out.println("Counter has reached 3 now will terminate");                             timer.cancel();//end the timer                             break;//end this loop                         }                         Thread.sleep(1000);                     } catch (InterruptedException ex) {                         ex.printStackTrace();                     }                 }             }         });          timer = new Timer("MyTimer");//create a new timer         timer.scheduleAtFixedRate(timerTask, 30, 3000);//start timer in 30ms to increment  counter          t.start();//start thread to display counter     } }