为什么我的recyclerview适配器不起作用？ /为什么班级没有上课？

Question

I have been trying to get the adapter for my RecyclerView to work, but I cannot get anything to display upon the cards, and also, the CycleTrails class does not run as the Logcat does not show any of the logs setup through the class... Before I setup the Adapter, everything worked fine, I could get all of the values from my CycleTrails class. But now, things are messed up and I cannot figure out why.

MainActivity.java (the onCreate part/only thing that I added with the adapter)

@Override
protected void onCreate(Bundle savedInstanceState) {


    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    rvItem = (RecyclerView) findViewById(R.id.rvItem);
    rvItem.setHasFixedSize(true);
    LinearLayoutManager manager = new LinearLayoutManager(this);
    rvItem.setLayoutManager(manager);
    ArrayList<Trails> finalData = getTrails();
    Adapter adapter = new Adapter(this, finalData);
    rvItem.setAdapter(adapter);

CycleTrails.java

public class CycleTrails extends MainActivity {

public static double LAT_MAX = myLatitude + (0.01 * 200);
public static double LAT_MIN = myLatitude - (0.01 * 200);
public static double LON_MAX = myLongitude + (0.01 * 200);
public static double LON_MIN = myLongitude - (0.01 * 200);

public static ArrayList<Trails> getTrails() {
    Log.d("trails", "Cycle trails running");
    ArrayList<Trails> trailList = new ArrayList<>();
    Trails t1 = new Trails(51.71, -3.36, "Bike Park Wales", "", "", "");
    Trails t2 = new Trails(51.66, -3.35, "Mountain Ash", "", "", "");
    Trails t3 = new Trails(50.50, -4.17, "FlyUp Downhill", "", "", "");
    trailList.add(t1);
    trailList.add(t2);
    trailList.add(t3);


    final ArrayList<Trails> localTrails = new ArrayList<>();
    for (final Trails trail : trailList) {
        Log.d("List running", "Local trail list");
        if (trail.lat > LAT_MIN && trail.lat < LAT_MAX && trail.lon > LON_MIN && trail.lon < LON_MAX) {
            localTrails.add(trail);
            Log.d("Calc", "Run code");


            final RequestBuilder weather = new RequestBuilder();

            final Request request = new Request();
            request.setLat(String.valueOf(trail.lat));
            Log.d("Lat used", String.valueOf(trail.lat));
            Log.d("Actual Lat", request.getLat());
            request.setLng(String.valueOf(trail.lon));
            Log.d("Lon used", String.valueOf(trail.lon));
            request.setUnits(Request.Units.UK);
            request.setLanguage(Request.Language.ENGLISH);
            request.addExcludeBlock(Request.Block.CURRENTLY);
            request.removeExcludeBlock(Request.Block.CURRENTLY);


            weather.getWeather(request, new Callback<WeatherResponse>() {
                @Override
                public void success(WeatherResponse weatherResponse, Response response) {
                    Log.d("Weather", "We have weather!");
                    Log.d("Location", weatherResponse.getTimezone());
                    trail.temp = String.valueOf(weatherResponse.getCurrently().getTemperature());
                    Log.d("Temperature", trail.temp);
                    trail.weather = weatherResponse.getCurrently().getIcon();
                }

                @Override
                public void failure(RetrofitError retrofitError) {
                    Log.d("Error while calling: ", "Weather");
                }


            });
        } else {
            Log.d("Too far", "Trails too far" + trail.name);
        }
    }
    return localTrails;
}

}

Adapter

public class Adapter extends RecyclerView.Adapter<Adapter.ViewHolder> {
private Context context;
public ArrayList <Trails> finalData;

public Adapter (Context context, ArrayList<Trails> finalData) {
    Log.d("Hello", "Adapter");
    this.context = context;
    this.finalData = finalData;
}

@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    LayoutInflater inflater = LayoutInflater.from(parent.getContext());
    Log.d("Hello", "2");
    View view = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.trail_card, parent, false);
    ViewHolder viewHolder = new ViewHolder(view);
    return viewHolder;
}

@Override
public void onBindViewHolder(ViewHolder holder, int position) {
    Trails trails = finalData.get(position);
    Log.d("Hello", "3");
    Picasso.with(context)
            .load("http://www.wigglestatic.com/product-media/5360108808/Wiggle-Road-Bike-Road-Bikes-Black-1WGMY16R7048UK0001-6.jpg?w=2000&h=2000&a=7")
            .placeholder(R.drawable.cycle)
            .error(android.R.drawable.stat_notify_error)
            .into(holder.locationImage);
    holder.locationText.setText(trails.name);
    Log.d("Location", trails.name);
    holder.temperatureText.setText(trails.temp);
    Log.d("Temperature", trails.temp);
    holder.weatherText.setText(trails.weather);
    holder.conditionsText.setText(trails.conditions);
}

@Override
public int getItemCount() {
    Log.d("Hello", "4");
    if(finalData != null) {
        Log.d("Hello", "5");
        return finalData.size();
    }
    return 0;
}

public static class ViewHolder extends RecyclerView.ViewHolder {

    public CardView cardView;
    public ImageView locationImage;
    public TextView locationText;
    public TextView temperatureText;
    public TextView weatherText;
    public TextView conditionsText;

    public ViewHolder(View itemView) {
        super(itemView);
        cardView = (CardView)itemView.findViewById(R.id.cardView);
        locationImage = (ImageView)itemView.findViewById(R.id.locationImage);
        locationText = (TextView)itemView.findViewById(R.id.locationText);
        temperatureText = (TextView)itemView.findViewById(R.id.temperatureText);
        weatherText = (TextView)itemView.findViewById(R.id.weatherText);
        conditionsText = (TextView)itemView.findViewById(R.id.conditionsText);
    }
}
}

Trails.java

public class Trails {
public String name;
public double lat;   // Object fields
public double lon;
public String temp;
public String weather;
public static String conditions;


Trails(double lat, double lon, String name, String temp, String weather, String conditions){ // construcor
    this.lat = lat;
    this.lon = lon;
    this.name = name;
    this.temp = temp;
    this.weather = weather;
    this.conditions = conditions;
}
}

This is the logcat for the whole app running

03-16 10:32:48.877 20535-20535/com.example.android.cycleuk D/Lat: 52.1981981981982
03-16 10:32:48.877 20535-20535/com.example.android.cycleuk D/Lon: -2.2341297062250933
03-16 10:33:19.859 20535-20542/com.example.android.cycleuk W/art: Suspending all threads took: 10.141ms
03-16 10:33:19.956 20535-20535/com.example.android.cycleuk D/Hello: Adapter
03-16 10:33:20.023 20535-20535/com.example.android.cycleuk D/Hello: 4
03-16 10:33:20.023 20535-20535/com.example.android.cycleuk D/Hello: 4
03-16 10:33:20.069 20535-20535/com.example.android.cycleuk D/Lat: 52.1981981981982
03-16 10:33:20.069 20535-20535/com.example.android.cycleuk D/Lon: -2.2341297062250933

Answer 1

Bind your adapter with recycleview..

ArrayList<Trails> finalData = getTrails();
Adapter adapter = new Adapter(this, finalData);
rvItem.setAdapter(adapter)

Answer 2

I think you have to change your Adapter class slightly.First you have to add Adapter to your recyclerView.Please be sure that recyclerView initialised with layout manger and not null.

Adapter adapter = new Adapter(this);
rvItem.setAdapter(adapter);

Here our Adapter class implementation.You have to create your List inside Adapter class.

public class Adapter {

ArrayList<Trails> finalData;
Context context;

public Adapter(Context context){
     this.context = context;
     finalData = new ArrayList<>();
}

.....

....

public void addItem(Trails data){
    finalData.add(data);
    notifyDataSetChanged(); // Note this method is important because it will let adapter know size of list changed and render the list
}

}

In your fragment or Activity class add that method

Adapter adapter = new Adapter(this);
rvItem.setAdapter(adapter);

/// here your methods what ever you want

dataList = getTrails();
for(Trails trails: dataList){
    adapter.addItem(trails);
}

I hope this will help you.

Answer 3

I think your getTrails method always return size 0 list that why you never get anything in recyclerview. All code is working fine . just check your code that you get any data in your list before setting it into recyclerview.



public static ArrayList<Trails> getTrails() {
    Log.d("trails", "Cycle trails running");
    ArrayList<Trails> trailList = new ArrayList<>();
    Trails t1 = new Trails(51.71, -3.36, "Bike Park Wales", "", "", "");
    Trails t2 = new Trails(51.66, -3.35, "Mountain Ash", "", "", "");
    Trails t3 = new Trails(50.50, -4.17, "FlyUp Downhill", "", "", "");
    trailList.add(t1);
    trailList.add(t2);
    trailList.add(t3);


    final ArrayList<Trails> localTrails = new ArrayList<>();
    for (final Trails trail : trailList) {
        Log.d("List running", "Local trail list");
        if (trail.lat > LAT_MIN && trail.lat < LAT_MAX && trail.lon > LON_MIN && trail.lon < LON_MAX) {
            localTrails.add(trail);
            Log.d("Calc", "Run code");


            final RequestBuilder weather = new RequestBuilder();

            final Request request = new Request();
            request.setLat(String.valueOf(trail.lat));
            Log.d("Lat used", String.valueOf(trail.lat));
            Log.d("Actual Lat", request.getLat());
            request.setLng(String.valueOf(trail.lon));
            Log.d("Lon used", String.valueOf(trail.lon));
            request.setUnits(Request.Units.UK);
            request.setLanguage(Request.Language.ENGLISH);
            request.addExcludeBlock(Request.Block.CURRENTLY);
            request.removeExcludeBlock(Request.Block.CURRENTLY);


            weather.getWeather(request, new Callback<WeatherResponse>() {
                @Override
                public void success(WeatherResponse weatherResponse, Response response) {
                    Log.d("Weather", "We have weather!");
                    Log.d("Location", weatherResponse.getTimezone());
                    trail.temp = String.valueOf(weatherResponse.getCurrently().getTemperature());
                    Log.d("Temperature", trail.temp);
                    trail.weather = weatherResponse.getCurrently().getIcon();
                }

                @Override
                public void failure(RetrofitError retrofitError) {
                    Log.d("Error while calling: ", "Weather");
                }


            });
        } else {
            Log.d("Too far", "Trails too far" + trail.name);
        }
    }
    return localTrails;
}

Answer 4

Your weather.getWeather() is not synchronous right?, this may cause your localTrails is always empty. And maybe you can try to put this code localTrails.add(trail) inside success method of your synchronous call.