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Android Android Fragments Introducing Fragments Handling Clicks

Handling clicks

I am not sure what I am doing wrong here. Followed the pattern from the lesson, but I cannot figure out to implement the fragment interface.

NewsFragment.java
public class NewsFragment extends Fragment {
    public interface NewsListener{
       void onNewsItemSelected(int index);
}
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_news, container, false);
        return view;
    }
}
MainActivity.java
public class MainActivity extends AppCompatActivity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        NewsFragment newsFragment = new NewsFragment();
        FragmentManager fragmentManager = getFragmentManager();
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        fragmentTransaction.add(R.id.placeholder, newsFragment);
        fragmentTransaction.commit();
    }
}

2 Answers

Ben Deitch
STAFF
Ben Deitch
Treehouse Teacher

Hi Eli! You need to implement the 'NewsListener' interface in your MainActivity class. First, you need to declare that MainActivity does implement the interface:

public class MainActivity extends AppCompatActivity implements NewsFragment.NewsListener {

And then you just need to override the interface's method in MainActivity. Hope that helps!

can i have a clear explanation of the code because i am lost

Ben Deitch
Ben Deitch
Treehouse Teacher

Sure!

First we need to create a new interface inside of the NewsFragment class:

public class NewsFragment extends Fragment {
    public interface NewsListener{
       void onNewsItemSelected(int index);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_news, container, false);
        return view;
    }
}

Then in MainActivity we implement this interface (which we access through the NewsFragment class) and override the 'onNewsItemSelected' method:

public class MainActivity extends AppCompatActivity implements NewsFragment.NewsListener {

    @Override
    public void onNewsItemSelected(int index) {

    }

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

        NewsFragment newsFragment = new NewsFragment();
        FragmentManager fragmentManager = getFragmentManager();
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        fragmentTransaction.add(R.id.placeholder, newsFragment);
        fragmentTransaction.commit();
    }
}

public class NewsFragment extends Fragment { public interface NewsListener{ void onNewsItemSelected(int index); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.fragment_news, container, false); return view; } }

public class MainActivity extends AppCompatActivity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main);

    NewsFragment newsFragment = new NewsFragment();
    FragmentManager fragmentManager = getFragmentManager();
    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
    fragmentTransaction.add(R.id.placeholder, newsFragment);
    fragmentTransaction.commit();
}

public class MainActivity extends AppCompatActivity implements NewsFragment.NewsListener { } }

thank you it worked

i have tried the above but i keep getting this error.

./MainActivity.java:1: error: MainActivity is not abstract and does not override abstract method onNewsItemSelected(int) in NewsListener public class MainActivity extends AppCompatActivity implements NewsFragment.NewsListener ^ 1 error