How to call a method after a delay in Android

Exploring alternate paths: Let's Fly(d) different

Android offers multiple ways to achieve delayed method execution, each tailored to different scenarios. Let's deep dive and figure out the right fit for you.

Reality Check: Timer & TimerTask

Java's Timer and TimerTask are old school players for scheduling tasks outside the main thread. Great if you are already using Timer for other stuff. Remember, "Old is Gold".

Timer timer = new Timer();
timer.schedule(new TimerTask() {
    @Override
    public void run() {
        launchSpaceship(); // Blast off spaceship after 2 sec delay, don't forget to fasten your seat belts!
    }
}, 2000);
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Control Freaks Alert: ScheduledExecutorService

If you crave control and precision, especially with concurrent tasks, look no further. ScheduledExecutorService is your knight in shining armor for scheduling tasks at fixed delays or rates. Time to conquer!

ScheduledExecutorService scheduler = Executors.newSingleThreadScheduledExecutor();
scheduler.schedule(() -> stealDeathStarPlans(),  secondsBeforeStormtroopersArrive(), TimeUnit.SECONDS); // "Help me, Obi-Wan Kenobi, You're my only hope."
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Kotlin Simplified: Lambda'fying

Kotlin loves simplicity and lambdas. With lambdas, Handler().postDelayed code becomes a breeze:

Handler(Looper.getMainLooper()).postDelayed({
    danceBabyGroot() // Puts baby Groot into dance mode after 1 sec, time for some cuteness overload!
}, 1000)
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Thread the Needle: Handling Background Tasks

Thread management is as pivotal as your code. Let's ensure our tasks are executed on correct threads to avoid any UI glitches or blocked main threads.

Main Thread vs Background: Choose your Battlefield

Unless specified, tasks via Handler, Timer, or ScheduledExecutorService follow the "Anywhere but not UI thread" rule. Heavy operations - background, UI updates - main thread. Mix it up and see your app crash faster than you say "Oops"!

Cleanup Time: Cancel Tasks

Remember to cancel any pending tasks when your activity or fragment is on its way out. Memory leaks can be as annoying as that sticky piece of gum on your shoe!

Picking the right wand: Tool Selection

Handler for simplicity, Timer for practicality, and ScheduledExecutorService for robustness - each tool suits unique application profiles. If you need a delay irrespective of your app's lifecycle, consider AlarmManager. It's the timekeeper outside your app's timeframe.

Crash Course: Handling Pitfalls

Uh-oh! User navigates away or the device rotates. Who you gonna call - Ghostbusters? Nope, we've got this!

Rotation Woes: Cancel Callbacks

Always remove callbacks in lifecycle methods like onDestroy() to avoid Ghosts of Destroyed Activities haunting your Handler.

@Override
protected void onDestroy() {
    super.onDestroy();
    ghostBusters.removeCallbacksAndMessages(null); // Clears all callbacks
}
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Configuration changes: Survival Guide

To make your scheduled tasks outlive configuration changes, consider ViewModel with LiveData. It's as easy as making instant noodles!