How to set delay in android

Question

public void onClick View v               TODO Auto-generated method stub         switch v getId             case R id rollDice              Random ranNum   new Random                int number   ranNum nextInt 6    1              diceNum setText    number               sum   sum   number              for i 0 i lt 8 i                     for j 0 j lt 8 j                          int value   Integer buttons i  j  getTag                        if value  sum                           inew i                          jnew j                           buttons inew  jnew  setBackgroundColor Color BLACK                                                     I want to insert a delay here                         buttons inew  jnew  setBackgroundColor Color WHITE                            break                                                                                           break                     I want to set a delay between the command between changing background  I tried using a thread timer and tried using run and catch  But it isn t working  I tried this   Thread timer   new Thread                 public void run                    try                                   buttons inew  jnew  setBackgroundColor Color BLACK                       sleep 5000                     catch  InterruptedException e                        e printStackTrace                                                        timer start       buttons inew  jnew  setBackgroundColor Color WHITE     But it is only getting changed to black

User · Answer

I think the easiest and most stable and the most useful way as of 2020 is using delay function of Coroutines instead of Runnable. Coroutines is a good concept to handle asynchronous jobs and its delay component will be this answer's focus.

WARNING: Coroutines need Kotlin language and I didn't convert the codes to Kotlin but I think everybody can understand the main concept..

Just add the Coroutines on your build.gradle:

implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.3.9'

Add a job to your class (activity, fragment or something) which you will use coroutines in it:

private var job: Job = Job()
override val coroutineContext: CoroutineContext
    get() = Dispatchers.Main + job

And you can use Coroutines anywhere on the class by using launch{ } body. So you can write your code like this:

public void onClick(View v) {

    launch {

        switch(v.getId()) {
            case R . id . rollDice :
            Random ranNum = new Random();
            int number = ranNum . nextInt (6) + 1;
            diceNum.setText("" + number);
            sum = sum + number;
            for (i= 0;i < 8;i++){
                for (j= 0;j < 8;j++){
                    int value =(Integer) buttons [i][j].getTag();
                    if (value == sum) {
                        inew = i;
                        jnew = j;

                        buttons[inew][jnew].setBackgroundColor(Color.BLACK);
                        delay(2000)
                        buttons[inew][jnew].setBackgroundColor(Color.WHITE);
                        break;
                    }
                }
        }
            break;

        }
    }
}

It's All...

Dont't forget that launch{} function is asynchronous and the for loop will not wait for delay function to finish if you write like this:

launch{
    buttons[inew][jnew].setBackgroundColor(Color.BLACK);
    delay(2000)
    buttons[inew][jnew].setBackgroundColor(Color.WHITE);
}

So, launch{ } should cover the for loop if you want all the for loop to wait for delay.

Another benefit of launch{ } is that you are making the for loop asynchronous, which means it is not gonna block the main UI thread of the application on heavy processes.

User · Answer

Here s an example where I change the background image from one to another with a 2 second alpha fade delay both ways - 2s fadeout of the original image into a 2s fadein into the 2nd image       public void fadeImageFunction View view         backgroundImage    ImageView  findViewById R id imageViewBackground       backgroundImage animate   alpha 0f  setDuration 2000           A new thread with a 2-second delay before changing the background image     new Timer   schedule              new TimerTask                     Override                 public void run                           you cannot touch the UI from another thread  This thread now calls a function on the main thread                     changeBackgroundImage                                     2000            this function runs on the main ui thread private void changeBackgroundImage        runOnUiThread new Runnable              Override         public void run                 backgroundImage    ImageView  findViewById R id imageViewBackground               backgroundImage setImageResource R drawable supes               backgroundImage animate   alpha 1f  setDuration 2000

User · Answer

If you want to do something in the UI on regular time intervals very good option is to use CountDownTimer   new CountDownTimer 30000  1000          public void onTick long millisUntilFinished             mTextField setText  seconds remaining      millisUntilFinished   1000                public void onFinish              mTextField setText  done                start

User · Answer

Try this code   import android os Handler      final Handler handler   new Handler    handler postDelayed new Runnable          Override     public void run                Do something after 5s   5000ms         buttons inew  jnew  setBackgroundColor Color BLACK            5000

User · Answer

You can use this  import java util Timer   and for the delay itself  add   new Timer   schedule                      new TimerTask                                              Override                         public void run                                                           if you need some code to run when the delay expires                                                                           delay    where the delay variable is in milliseconds  for example set delay to 5000 for a 5-second delay

User · Answer

If you use delay frequently in your app  use this utility class  import android os Handler    public class Utils           Delay mechanism      public interface DelayCallback          void afterDelay               public static void delay int secs  final DelayCallback delayCallback           Handler handler   new Handler            handler postDelayed new Runnable                  Override             public void run                     delayCallback afterDelay                             secs   1000      afterDelay will be executed after  secs 1000  milliseconds            Usage      Call this method directly from java file  int secs   2     Delay in seconds  Utils delay secs  new Utils DelayCallback          Override     public void afterDelay                Do something after delay

User · Answer

Handler answer in Kotlin    1 - Create a top-level function inside a file  for example a file that contains all your top-level functions     fun delayFunction function    - gt  Unit  delay  Long        Handler   postDelayed function  delay      2 - Then call it anywhere you needed it    delayFunction   myDelayedFunction      300

User · Answer

Using the Thread sleep millis  method

User · Answer

You can use CountDownTimer which is much more efficient than any other solution posted  You can also produce regular notifications on intervals along the way using its onTick long  method  Have a look at this example showing a 30seconds countdown     new CountDownTimer 30000  1000             public void onFinish                     When timer is finished                  Execute your code here              public void onTick long millisUntilFinished                     millisUntilFinished    The amount of time until finished              start

[java] How to set delay in android?

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