CODEWITHSUNDEEP
javaandroiddelay
NokisDemox
NokisDemox

Reputation: 11

Android Studio Delay inside Loop

I want to make a loop, the times the user wants but with a delay of 3 seconds.

This is the code:

for (i = 0;i < n1; i++){
            new Handler().postDelayed(new Runnable() {
                @Override
                public void run() {
                    Toast.makeText(KeyMapCreator.this, "Try number " + i,Toast.LENGTH_SHORT).show(); ActionIwantToDo();
                }
            },3000);
        }

The variable i is the one that the user sets. The problem is that the toast doesn't show up every 3 seconds, it just do like a normal loop without delay. I thought it was because of the time of the toast but if i set the time to 20 secs still being the same. Someone knows how to make a proper delay inside a loop???

Upvotes: 0

Views: 2535

Answers (2)

CMcAllister
CMcAllister

Reputation: 176

The problem you have is that your loop creates many handlers at once that delay for 3 seconds and then show a toast. They do not wait for each other, and because they are created within milliseconds of each other they will show the toast at the same time.

I'm not sure what you are trying to accomplish, and a loop is probably not what you want. However this is a way to get the toast to display after 3 seconds and every 3 seconds after for a number of times.

For this we will use recursion because it will make it so that you are not blocked on the main thread.

  1. Call doSomething (the recursive function) from where you need the function to start (remember that the second variable is the number of times you want it to run, and 0 is just required as a counter)
doSomething(0, 3)
  1. create doSomething
private void doSomething(int i, int n) {
   new Handler().postDelayed(new Runnable() {
      @Override
      public void run() {
         if (i < n) {
            Toast.makeText(KeyMapCreator.this, "Try number " + i,Toast.LENGTH_SHORT).show();
            actionIWantToDo();
            doSomething(i+1, n);
         }
      }
   }, 3000);
}

Upvotes: 3

Doug Stevenson
Doug Stevenson

Reputation: 317487

A Handler just schedules some work for later execution. It doesn't actually block the current thread. All you're doing is scheduling n1 items of work to execute three seconds later, which will all execute in sequence on that exact delay.

You don't really ever want to write code to block the main thread. Ever. It will make your app appear to be unresponsive.

Upvotes: 0

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