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Android

Posted by Connor Nesbitt
Connor Nesbitt
4,824 Points

Moving Work from the Main Thread to an AsyncTask code challenge help

I'm stuck on part one of this code challenge. The question is: Create a private class inside MainListActivity named 'CustomAsyncTask' and have it extend AsyncTask. Don't put anything in it yet, but AsyncTask requires 3 generic types: use 'Object', 'Void', and 'String'. Hint: The format will be AsyncTask<type1, type2, type3>. Here is my code: private class CustomAsyncTask extends AsyncTask<Object, Void, String>{} it keeps giving me a Complication error and I have no idea why. Can someone help me please?

4 Answers

Ernest Grzybowski
Ernest Grzybowski
Treehouse Project Reviewer

Please try to post as much of your code as it may be easier to find where your problem may be. That's the only way we may be able to see a bracket missing. Nonetheless, the first thing I notice from reading the question is that there are two parts to the solution. It seems that you only did the first half.

Let's start with the code they give you:

public class MainListActivity extends ListActivity {

    public static final String URL = "http://www.teamtreehouse.com";
    public static final String TAG = MainListActivity.class.getSimpleName();

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main_list);

        try {
            URL treehouseUrl = new URL(URL);
            HttpURLConnection connection = (HttpURLConnection) treehouseUrl.openConnection();
            connection.connect();
            int responseCode = connection.getResponseCode();
        }
        catch (MalformedURLException e) {
            Log.e(TAG, "MalformedURLException caught!", e);
        }
        catch (IOException e) {
            Log.e(TAG, "IOException caught!", e);
        }
    }
}

They ask "Create a private class inside MainListActivity named 'CustomAsyncTask' and have it extend AsyncTask." Let's do this below

public class MainListActivity extends ListActivity {

    public static final String URL = "http://www.teamtreehouse.com";
    public static final String TAG = MainListActivity.class.getSimpleName();

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main_list);

        try {
            URL treehouseUrl = new URL(URL);
            HttpURLConnection connection = (HttpURLConnection) treehouseUrl.openConnection();
            connection.connect();
            int responseCode = connection.getResponseCode();
        }
        catch (MalformedURLException e) {
            Log.e(TAG, "MalformedURLException caught!", e);
        }
        catch (IOException e) {
            Log.e(TAG, "IOException caught!", e);
        }
    }
  private class CustomAsyncTask extends AsyncTask {

  }
}

Next they say "Don't put anything in it yet, but AsyncTask requires 3 generic types: use 'Object', 'Void', and 'String'."

public class MainListActivity extends ListActivity {

    public static final String URL = "http://www.teamtreehouse.com";
    public static final String TAG = MainListActivity.class.getSimpleName();

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main_list);

        try {
            URL treehouseUrl = new URL(URL);
            HttpURLConnection connection = (HttpURLConnection) treehouseUrl.openConnection();
            connection.connect();
            int responseCode = connection.getResponseCode();
        }
        catch (MalformedURLException e) {
            Log.e(TAG, "MalformedURLException caught!", e);
        }
        catch (IOException e) {
            Log.e(TAG, "IOException caught!", e);
        }
    }
  private class CustomAsyncTask extends AsyncTask<Object, Void, String> {

  }
}

That should pass the first challenge question. Hope the breakdown helps!

Connor Nesbitt
Connor Nesbitt
4,824 Points

Thanks for your help! But it is still saying that the answer is wrong for some reason. It keeps on giving me this every time I put the code in:Compilation Error! Verify that you have the generic parameters '<Object, Void, String>' between 'extends AsyncTask' and the opening curly brace, and check the rest of your syntax. And I put in the code exactly how you've done it.

Ernest Grzybowski
Ernest Grzybowski
Treehouse Project Reviewer

Make sure the imports are there!

Connor Nesbitt
Connor Nesbitt
4,824 Points

The imports are there and it is still giving me an error message. :/

Ernest Grzybowski
Ernest Grzybowski
Treehouse Project Reviewer

Please post your entire code, it's difficult to tell why it's not going though.

This works for me without a hitch.

package com.example;

import android.os.Bundle;
import android.view.View;
import java.io.IOException;
import java.net.MalformedURLException;
import android.util.Log;
import android.os.AsyncTask;

public class MainListActivity extends ListActivity {

    public static final String URL = "http://www.teamtreehouse.com";
    public static final String TAG = MainListActivity.class.getSimpleName();

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main_list);

        try {
            URL treehouseUrl = new URL(URL);
            HttpURLConnection connection = (HttpURLConnection) treehouseUrl.openConnection();
            connection.connect();
            int responseCode = connection.getResponseCode();
        }
        catch (MalformedURLException e) {
            Log.e(TAG, "MalformedURLException caught!", e);
        }
        catch (IOException e) {
            Log.e(TAG, "IOException caught!", e);
        }
    }
  private class CustomAsyncTask extends AsyncTask<Object, Void, String>{

  }
}
Connor Nesbitt
Connor Nesbitt
4,824 Points

I figured it out. I had the code in the wrong spot....Thank you much for your help! Though I am having some issues with the second part of the code challenge. Here is my code:

package com.example;

import android.os.Bundle;
import android.view.View;
import java.io.IOException;
import java.net.MalformedURLException;
import android.util.Log;
import android.os.AsyncTask;

public class MainListActivity extends ListActivity {

    public static final String URL = "http://www.teamtreehouse.com";
    public static final String TAG = MainListActivity.class.getSimpleName();

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main_list);

        try {
            URL treehouseUrl = new URL(URL);
            HttpURLConnection connection = (HttpURLConnection) treehouseUrl.openConnection();
            connection.connect();
            int responseCode = connection.getResponseCode();
        }
        catch (MalformedURLException e) {
            Log.e(TAG, "MalformedURLException caught!", e);
        }
        catch (IOException e) {
            Log.e(TAG, "IOException caught!", e);
        }
    }
   private class CustomAsyncTask extends AsyncTask<Object, Void, String>{
     @Override
     protected String doInBackground(Object... params) {
     "";
     }

      }
}

(For some reason it does not post the second part of the AsyncTask code onto the reply. It is there though)

Ernest Grzybowski
Ernest Grzybowski
Treehouse Project Reviewer

Connor Nesbitt you are really close, but you first need to under stand that a method can either return something or it can return nothing. The challenge states:

Make it 'protected', return a String, and then simply return an empty String in the body.

  • Make the method protected :white_check_mark:
  • Make the method return a String :white_check_mark:
  • Simply return an empty String in the body :x:

You wrote:

"";

but that does not return a string. That actually won't even compile. You must use return followed by what you want to return.

Examples:

public String getName(){
return myName;
}

//or

public int getAge(){
return 21;
}

//or

public String getName(){
return "Ernest";
}

With all of that laid out in front of you, you should be able to make it past the second challenge! :grin:

Jeremy Miller
Jeremy Miller
2,455 Points
Jeremy Miller
Jeremy Miller
2,455 Points

I must be having a bad moment im stuck this keeps giving me this error.......

Bummer! Compilation Error! Verify that the 'doInBackground()' method starts with 'protected String' and actually returns a String inside the curly braces, and check the rest of your syntax

private class CustomAsyncTask extends AsyncTask<Object,Void,String>{

@Override
protected String doInBackground(Object...params){
  return "";

}

Connor Nesbitt
Connor Nesbitt
4,824 Points
Connor Nesbitt
Connor Nesbitt
4,824 Points

I forgot the <Object, Void, String> code in between the AsyncTask and the open curly brace. but it still gives me the error. private class CustomAsyncTask extends AsyncTask<Object, Void, String> {}

Connor Nesbitt
Connor Nesbitt
4,824 Points
Connor Nesbitt
Connor Nesbitt
4,824 Points

Yup, that was my problem. Thank you so much for helping me through this stressful time!

Connor Nesbitt
Connor Nesbitt
4,824 Points
Connor Nesbitt
Connor Nesbitt
4,824 Points

Yup, that was my problem. Thank you so much for helping me through this stressful time!