I have a requirement , where a HashMap has some keys and values. To be more specific values are either "true" or "false", I need to change theses values i.e from "true" to "false" or vice versa depending on the time.
Like If there has been more than 30 minutes since the "false" value was inserted , so it should now change to "true" (and vice versa).
I know it can be achieved by a Thread, but is there any other way it can be done , may be through some Java API ???
All techniques will use a Thread. If you mean you don't want to create your own background thread and handle the delays yourself etc you could use a java.util.Timer.
For each entry you want to flip every 30 minutes add a TimerTask to the timer. If you want to continue flipping that entry every 30 minutes you can choose either fixed rate or fixed delay depending on your requirements.