Why are there two Timer classes in Java(one under javax.swing, one under java.util )?

Question

I am really confused about this . Java has two Timer classes, one under swing , and one under util ... why is that? Which one should I use if I want to simply run X every Y seconds? Does this mean if I'm building a GUI I have to use the swing version for a timer?

thanks!

Answer 1

Here is the difference between javax.swing.Timer and java.util.Timer:

javax.swing.Timer

• suitable for simpler cases, using low numbers of timers (say less than a dozen)
• runs ActionListener objects on the event dispatch thread
• can directly update the GUI, without using EventQueue.invokeLater
• if the task runs entirely in the event dispatch thread (that is, if it does not spawn a worker thread), then the GUI will remain responsive only if the task does not take very long (say under 300 milliseconds)

java.util.Timer

• more scalable than javax.swing.Timer, and with additional scheduling features
• runs TimerTask objects on a private thread
• needs to use EventQueue.invokeLater to update the GUI

You can use Swing timers in two ways:

• To perform a task once, after a delay. For example, the tool tip manager uses Swing timers to determine when to show a tool tip and when to hide it.
• To perform a task repeatedly. For example, you might perform animation or update a component that displays progress toward a goal.

Here is the sources for above information http://www.javapractices.com/topic/TopicAction.do?Id=160 and http://docs.oracle.com/javase/tutorial/uiswing/misc/timer.html

Which one should I use if I want to simply run X every Y seconds?

Depending upon what you are interacting with. If you are interacting with GUI then use javax.swing.Timer , else use java.util.Timer.

Does this mean if I'm building a GUI I have to use the swing version for a timer?

YES