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1.06 Hook the adapter up to the ListView
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Lyla committed Mar 4, 2015
1 parent 0281f77 commit 1d42493
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6 changes: 6 additions & 0 deletions app/src/main/java/com/example/android/sunshine/app/MainActivity.java
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Expand Up @@ -24,6 +24,7 @@
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
Expand Down Expand Up @@ -101,6 +102,11 @@ public View onCreateView(LayoutInflater inflater, ViewGroup container,
weekForecast);

View rootView = inflater.inflate(R.layout.fragment_main, container, false);

// Get a reference to the ListView, and attach this adapter to it.
ListView listView = (ListView) rootView.findViewById(R.id.listview_forecast);
listView.setAdapter(mForecastAdapter);

return rootView;
}
}
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13 comments on commit 1d42493

@martipello
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Is this still current when I create the project I get a separate main activity fragment with a single fragment inside as such I've changed
ListView listView = (ListView) rootView.findViewById(R.id.listview_forecast);
To
ListView listView = (ListView) getActivity().findViewById(R.id.listview_forecast);
Which causes a force close

@ratanachai
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I ran a test for you. That's because getActivity().findViewById returned null.

@Pvag
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@Pvag Pvag commented on 1d42493 Jun 29, 2015

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@martipello did you create rootView?
See line 104:
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
(and then return it in line 110).
The code is still valid if you create rootView like that and then return it at the end of onCreateView method.

@martipello
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@martipello martipello commented on 1d42493 Jun 30, 2015 via email

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@austinov
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Try to check content of fragment_main.xml for existing the following line (in ListView control):
android:id="@+id/listview_forecast"

@StaziaPhoenix
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If anyone else encounters this problem, I had a similar situation.

The layouts_v11 folder contains another xml file named fragment_main.xml. This is the one we played with in our first UI exercise (fiddling with design mode). Though I am unfamiliar with all this, I imagine that this folder and the files within are used in adapting to different screen sizes. Since my test device is a Nexus 7 tablet, the v11 fragment_main was being called in MainActivity.java, and did not contain the ListView element/id. Thus the null pointer.

Either renaming this file or changing it to do what we want it to should resolve the issue. Since I don't know how to adapt a UI to another screen size, I renamed the file. Code now progresses as expected.

@sujin5310
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In android 1.4, I get two java files mainactivity and mainactivity fragment. I couldnt find any placeholder fragment. Also I am getting an error in rootview (Rootview is never assigned). What should I do now

@KritiSharan
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For your mainactivity fragment, edit the code like this and it will work:

`public class MainActivityFragment extends Fragment {

public MainActivityFragment() {
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    String[] data = {
            "Mon 6/23 - Sunny - 31/17",
            "Tue 6/24 - Foggy - 21/8",
            "Wed 6/25 - Cloudy - 22/17",
            "Thurs 6/26 - Rainy - 18/11",
            "Fri 6/27 - Foggy - 21/10",
            "Sat 6/28 - TRAPPED IN WEATHERSTATION - 23/18",
            "Sun 6/29 - Sunny - 20/7"
    };
    List<String> weekForecast = new ArrayList<String>(Arrays.asList(data));
    ArrayAdapter<String> mForecatAddapter = new ArrayAdapter<String>(getActivity(),
            R.layout.list_item_forecast, R.id.list_item_forecast_textview, weekForecast);

    View rootView = inflater.inflate(R.layout.fragment_main, container, false);

    ListView listView =  (ListView) rootView.findViewById(R.id.listview_forecast);
    listView.setAdapter(mForecatAddapter);

    return rootView;
}

}`

@Teemmy
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@Teemmy Teemmy commented on 1d42493 Apr 18, 2016

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Can someone please help me out... "R.id.container" the container id belongs to where?
@OverRide
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if(savedInstanceState == null){
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment())
.commit();
}
/Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);/
}

@KritiSharan
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R.id.container refers to the ID of a View in your MainActivity's layout file, which contains the fragment.

@shubham0677
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Please help. Getting this exception:

" java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference"

`public static class PlaceholderFragment extends Fragment {

    public PlaceholderFragment(){
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View rootView = inflater.inflate(R.layout.fragment_main, container, false);
        String[] forecastArray={
                "Today-Sunny-80/83",
                "Tommorow-Rain-30/40",
                "Wed-Rain-30/40",
                "Thur-Rain-30/40",
                "Fri-Rain-30/40",
                "Sat-Rain-30/40",
                "Sun-Rain-30/40"
        };
        List<String> weekForecast=new ArrayList<String>(Arrays.asList(forecastArray));

        ArrayAdapter<String> mForecastAdapter=new ArrayAdapter<String>(getActivity(),R.layout.fragment_main, R.id.list_item_forecast_textview , weekForecast);

        ListView forecast_list=(ListView) rootView.findViewById(R.id.listview_forecast);
        forecast_list.setAdapter(mForecastAdapter);

        return rootView;
    }
}`

@nunohpinheiro
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Hello everyone! Can you please help me?

At this point, I am getting a null pointer exception and I cannot understand why... It's accused in the following line of MainActivity:
"listView.setAdapter(mForecastAdapter);"

Thanks in advance!

@mundre
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@mundre mundre commented on 1d42493 Sep 14, 2016

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@yvasilyev92 , How have you defined your activity_main.xml ? Just these lines will throw up error:

<?xml version="1.0" encoding="utf-8"?>
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.android.sunshine.app.MainActivity"
android:id="@+id/container">

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