Handling Task Completion

MainActivity.java

package com.example.vinayaka.test;

import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import com.sigmaV5.FetchResult.*;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState)  {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button b = (Button) findViewById(R.id.okBtn);
        b.setOnClickListener(v -> {
            try {
                AsyncTask<Void,Void,String> task =  new ResultFetchTask(this, result -> new AlertDialog.Builder(MainActivity.this).setMessage(result).show()).execute();
                //Lambdas!
            }
            catch (Exception e){
                Log.e("MU","as",e);
            }
        });
    }
}