为什么mDailyWeather变量为null？

Question

我正在尝试使用ForecastIO API

我可以成功获取此API的当前天气数据，但是我不了解如何正确检索此API的每日天气数据。

我认为问题在于MainActivity.java中的getDailyForecast方法，该方法从第200行开始。

package com.joshbgold.stormy;

import android.content.Context;
import android.graphics.drawable.Drawable;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.view.View;
import android.widget.ImageView;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;

import com.squareup.okhttp.Call;
import com.squareup.okhttp.Callback;
import com.squareup.okhttp.OkHttpClient;
import com.squareup.okhttp.Request;
import com.squareup.okhttp.Response;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.IOException;

import butterknife.ButterKnife;
import butterknife.InjectView;


public class MainActivity extends ActionBarActivity {

    public static final String TAG = MainActivity.class.getSimpleName();

    private CurrentWeather mCurrentWeather;
    private Day[] mDailyWeather;

    @InjectView(R.id.timeLabel) TextView mTimeLabel;  //declares time variable, and links it to the layout
    @InjectView(R.id.temperatureLabel) TextView mTempuratureLabel;
    @InjectView(R.id.humidityValue) TextView mHumidityValue;
    @InjectView(R.id.precipValue) TextView mPrecipValue;
    @InjectView(R.id.summaryLabel) TextView mSummaryLabel;
    @InjectView(R.id.iconImageView) ImageView mIconImageView;
    @InjectView(R.id.windValue) TextView mWindValue;
    @InjectView(R.id.refreshImageView) ImageView mRefreshImageView;
    @InjectView(R.id.progressBar) ProgressBar mProgressBar;
    @InjectView(R.id.highTempValue) TextView mHighTemperature;
    @InjectView(R.id.lowTempValue) TextView mLowTemperature;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ButterKnife.inject(this);  //allows us to use a shortcut to link layout elements

        mProgressBar.setVisibility(View.INVISIBLE);

        final double latitude = 45.5233;
        final double longitude = -122.6762;

        mRefreshImageView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                getForecast(latitude, longitude);
            }
        });

        getForecast(latitude, longitude);
        Log.d(TAG, "Main UI code is running!");

    }

    private void getForecast(double latitude, double longitude) {
        String apiKey = "21526f648c8ed449028d2533c39e7f4f";

        String forecastURL = "https://api.forecast.io/forecast/" + apiKey + "/" + latitude + "," + longitude;

        if (isNetworkAvailable()) {

            toggleRefresh();

            OkHttpClient client = new OkHttpClient();
            Request request = new Request.Builder()
                    .url(forecastURL)
                    .build();

            Call call = client.newCall(request);
            call.enqueue(new Callback() {
                @Override
                public void onFailure(Request request, IOException e) {
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            toggleRefresh();
                        }
                    });
                    alertUserAboutError();
                }

                @Override
                public void onResponse(Response response) throws IOException {
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            toggleRefresh();
                        }
                    });

                    try {
                        String jsonData = response.body().string();
                        Log.v(TAG, jsonData);
                        if (response.isSuccessful()) {
                            mCurrentWeather = getCurrentDetails(jsonData);
                            runOnUiThread(new Runnable() {
                                @Override
                                public void run() {
                                    updateDisplay();
                                }

                            });

                            mDailyWeather = getDailyForecast(jsonData);
                            runOnUiThread(new Runnable() {
                                @Override
                                public void run() {
                                    updateDisplay();
                                }

                            });

                            Log.v(TAG, response.body().string());
                        } else {
                            alertUserAboutError();
                        }
                    } catch (IOException e) {
                        Log.e(TAG, "Exception caught: ", e);
                    }
                    catch (JSONException e){
                        Log.e(TAG, "Exception caught: ", e);
                    }

                }
            });
        }
    }

    private void toggleRefresh() {
        if (mProgressBar.getVisibility() == View.INVISIBLE) {
            mProgressBar.setVisibility(View.VISIBLE);
            mRefreshImageView.setVisibility(View.INVISIBLE);
        }
        else {
            mProgressBar.setVisibility(View.INVISIBLE);
            mRefreshImageView.setVisibility(View.VISIBLE);
        }
    }

     private void updateDisplay() {
        mTempuratureLabel.setText(mCurrentWeather.getTemperature() + "");
        mTimeLabel.setText("At " + mCurrentWeather.getFormattedTime() + " it will be");
        mHumidityValue.setText(mCurrentWeather.getHumidity() + "%");
        mPrecipValue.setText(mCurrentWeather.getPrecipChance() + "%");
        mWindValue.setText(mCurrentWeather.getWindSpeed()+ " MPH");
        mHighTemperature.setText(mDailyWeather[0].getHighTemperature() + "");
        mLowTemperature.setText(mDailyWeather[0].getLowTemperature() + "");
        mSummaryLabel.setText(mCurrentWeather.getSummary());

        Drawable drawable = getResources().getDrawable(mCurrentWeather.getIconId());
        mIconImageView.setImageDrawable(drawable);
    }

    private CurrentWeather getCurrentDetails(String jsonData) throws JSONException{
        JSONObject forecast = new JSONObject(jsonData);
        String timezone = forecast.getString("timezone");
        Log.i(TAG, "From JSON: " + timezone);

        JSONObject currently = forecast.getJSONObject("currently");

        CurrentWeather currentWeather = new CurrentWeather();

        currentWeather.setHumidity(currently.getDouble("humidity"));
        currentWeather.setTime(currently.getLong("time"));
        currentWeather.setIcon(currently.getString("icon"));
        currentWeather.setPrecipChance(currently.getDouble("precipProbability"));;
        currentWeather.setSummary(currently.getString("summary"));
        currentWeather.setTemperature(currently.getDouble("temperature"));
        currentWeather.setTimeZone(timezone);
        currentWeather.setWindSpeed(currently.getDouble("windSpeed"));
        currentWeather.setWindBearing(currently.getInt("windBearing"));

        Log.d(TAG, currentWeather.getFormattedTime());
        Log.d(TAG, String.valueOf(currentWeather.getWindSpeed()) + " MPH");
        Log.d(TAG, String.valueOf(currentWeather.getWindBearing()) + " degrees");

        return currentWeather;
    }

    private Day[] getDailyForecast(String jsonData) throws JSONException {
        JSONObject forecast = new JSONObject(jsonData);
        String timezone = forecast.getString("timezone");

        JSONObject daily = forecast.getJSONObject("daily");
        JSONArray data = daily.getJSONArray("data");

        Day[] mDailyWeather = new Day[data.length()];

        for (int i=0; i < data.length(); i++) {
            JSONObject jsonDay = data.getJSONObject(i);
            Day day = new Day();
            day.setTimeZone(timezone);
            day.setHighTemperature(jsonDay.getDouble("temperatureMax"));
            day.setLowTemperature(jsonDay.getDouble("temperatureMin"));

            mDailyWeather[i] = day;

            Log.d(TAG, String.valueOf(day.getHighTemperature() + " degrees F"));
            Log.d(TAG, String.valueOf(day.getLowTemperature() + " degrees F"));
        }
        return mDailyWeather;
    }

    private boolean isNetworkAvailable() {
        ConnectivityManager manager = (ConnectivityManager)
                getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo networkInfo = manager.getActiveNetworkInfo();
        boolean isAvailable = false;
        if(networkInfo != null && networkInfo.isConnected()){
            isAvailable = true;
        }
        else{
            Toast.makeText(this, getString(R.string.network_unavailable_message),
                    Toast.LENGTH_LONG).show();
        }
        return isAvailable;
    }

    private void alertUserAboutError() {
        AlertDialogFragment dialog = new AlertDialogFragment();
        dialog.show(getFragmentManager(),"error_dialog");
    }


}

Answer 1

您正在初始化mDailyWeather之前调用onUpdateDisplay 。

像这样删除第一个电话：

 mCurrentWeather = getCurrentDetails(jsonData);
 mDailyWeather = getDailyForecast(jsonData);
 runOnUiThread(new Runnable() {
     @Override
     public void run() {
         updateDisplay();
     }
 });