CODEWITHSUNDEEP
androidandroid-asynctask
Brendon
Brendon

Reputation: 1368

Retrieving a Value inside of AsyncTask method in Android

I am implementing JSON array which I retrieved using AsyncTask method for background process,

I have an array variable which is declared before OnCreate and initialized with some value,

String [] str=new String[100];

Storing in tat array variable while parsing the json array like this in a for loop,

str[i]=c.getString(TAG_NAME);

storing perfectly, I did Log and its showing in logcat too,

but the problem is when I use "str" array variable outside of my function like this, 

void func()
{
List<String> top250 = new ArrayList<String>();
for(int x=0;x<str.length;x++)
{

    top250.add(str[x]);

}
}

The str variable is storing only the string "null" for initialized memory.

It's storing "null" for 100 times.

So how to fetch the value which is processed in doInBackground method inside of AsyncTask?

Upvotes: 2

Views: 104

Answers (2)

Nitesh Tiwari
Nitesh Tiwari

Reputation: 4762

Edit: Asyntask Example for reference Code and concept here.

As we Know AsynTask has three parameters 

new `AsynTask < Params , Progress , Result >`

You can do Like This:

new AsyncTask<Void, Void, String>(){

                @Override
                protected String doInBackground(Void... params) {

                             //Parse your json here
                             //You will get this result into result of onPostExceute()

                                       return json;
                }

                @Override
                protected void onPostExecute(String result) {
                                        //Use your result here
                    super.onPostExecute(result);
                }
                      }.execute();

Using this you can get your String(here) or WhatEver you defined into Result Section of AsynTask

Hope this could Help

Upvotes: 1

Graham Smith
Graham Smith

Reputation: 25757

You can return your list of strings in post execute()

private class LongOperation extends AsyncTask<String, Void, List<String>> {

    @Override
    protected List<String> doInBackground(String... params) {

        List<String> top250 = new ArrayList<String>();
        for(int x=0;x<str.length;x++)
        {

            top250.add(str[x]);

        }

        return top250;
    }

    @Override
    protected void onPostExecute(List<String> result) {

        //validate result and assign to something useful like a field

    }

    @Override
    protected void onPreExecute() {}

    @Override
    protected void onProgressUpdate(Void... values) {}
}

Then you could assign result to a field somewhere in your class after validating it.

Upvotes: 2

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