Android asyncTask cant pass ArrayList<> as param

Question

I have this asyncTask:

public class CreateZipFile extends AsyncTask<ArrayList<String>, Integer, File> {

    Context context;

    public CreateZipFile(Context context){
        this.context = context;
    }

    protected File doInBackground(ArrayList<String>... files) {
        for(String file : files){
        //DO SMTH
        }
        return null;
    }

    public void onProgressUpdate(Integer... progress) {

    }

    public void onPostExecute() {

    }
}

however in my foreach loop I get error saying required ArrayList found String. Is it possible that asynctask converts my arraylist to String?

please read the async task documentation developer.android.com/reference/android/os/… — SaravInfern
– SaravInfern, Commented Nov 9, 2016 at 12:18

Blackbelt · Accepted Answer · 2016-11-09 12:17:24Z

3

you don't need AsyncTask<ArrayList<String>, unless you want to pass an array of ArrayList. The ... operator, is called varargs, and it can be accessed like an array. E.g. if you call

 new CreateZipFile().execute("a", "b");

then, in

protected File doInBackground(String... files) {

files[0] contains a and files[1] contains b. If you still want to pass the ArrayList, then you have to change your code like follows:

 for (ArrayList<String> l : files) {
       for(String file : l){
           //DO SMTH
       }
   }

answered Nov 9, 2016 at 12:17

Blackbelt

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Comments

Andrii Omelchenko · Accepted Answer · 2016-11-09 12:19:02Z

2

Try to change protected File doInBackground(ArrayList<String>... files) { by this way:

protected File doInBackground(ArrayList<String>... files) {
        ArrayList<String> passedFiles = files[0]; //get passed arraylist

        for(String file : passedFiles){
        //DO SMTH
        }
        return null;
    }

answered Nov 9, 2016 at 12:19

Andrii Omelchenko

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Comments

Shivam Dawar · Accepted Answer · 2019-04-01 13:18:01Z

0

You have to do something like this

    Items[] items = new Items[SIZE]; 
    items[0]=ITEM1;
    items[1]=ITEM2;
    items[2]=ITEM3;
    .
    .
    .

    new InsertItemsAsync().execute(items);


private static class InsertItemsAsync extends AsyncTask<Items,Void,Void>{
        @Override
        protected Void doInBackground(Items... items) {
          // perform your operations here
            return null;
        }
    }

answered Apr 1, 2019 at 13:18

Shivam Dawar

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