安卓工作室"Unfortunately my project has stopped"

Question

项目本身没有报告任何错误，但当我用模拟器运行我的项目时，它弹出"不幸的是，项目已经停止"，有人能看看我的项目并知道是什么错误吗？我得到以下logcat错误：

Process: edu.drexel.weatherundergroundapi, PID: 1800
java.lang.RuntimeException: Unable to start activity ComponentInfo{edu.drexel.weatherundergroundapi/edu.drexel.weatherundergroundapi.MainActivity}: java.lang.NullPointerException: storage == null
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: java.lang.NullPointerException: storage == null
at java.util.Arrays$ArrayList.<init>(Arrays.java:38)
at java.util.Arrays.asList(Arrays.java:155)
at android.widget.ArrayAdapter.<init>(ArrayAdapter.java:128)
at edu.drexel.weatherundergroundapi.CustomListAdapter.<init>(CustomListAdapter.java:35)
at edu.drexel.weatherundergroundapi.MainActivity.onCreate(MainActivity.java:25)
at android.app.Activity.performCreate(Activity.java:5933)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
            at android.app.ActivityThread.access$800(ActivityThread.java:144)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)

有三个java类和三个xml文件：1。主要活动.java 2。CustomListAdapter.java 3。MyBgTask.java 4。listView.xml5.activity_main.xml

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        MyBgTask asyncTask = new MyBgTask();
        CustomListAdapter adapter = new CustomListAdapter(this, asyncTask.getTimeArray(), asyncTask.getConditionArray(),
                                    asyncTask.getTempArray(), asyncTask.getHumidityArray(), asyncTask.getUrls());
        ListView list = (ListView) findViewById(R.id.listView);
        list.setAdapter(adapter);
        asyncTask.execute();
    }
    /*public void onListItemClick(ListView lv, View view, int position, int imgid) {
        String Slecteditem= (String)getListAdapter().getItem(position);
        Toast.makeText(this, Slecteditem, Toast.LENGTH_SHORT).show();
    }*/

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

2. CustomListAdapter.java:

   public class CustomListAdapter extends ArrayAdapter<String> {
   private final Activity context;
   private final String[] time;
   private final String[] condition;
   private final String[] temp;
   private final String[] humidity;
   private final String[] url;
   public CustomListAdapter(Activity context, String[] time, String[] condition, String[] temp, String[] humidity, String[] url)
   {
       super(context, R.layout.listview, time);
       this.context = context;
       this.time = time;
       this.condition = condition;
       this.temp = temp;
       this.humidity = humidity;
       this.url = url;
   }
   private Bitmap getImageBitmap(String url) {
       Bitmap bm = null;
       try {
           URL aURL = new URL(url);
           URLConnection conn = aURL.openConnection();
           conn.connect();
           InputStream is = conn.getInputStream();
           BufferedInputStream bis = new BufferedInputStream(is);
           bm = BitmapFactory.decodeStream(bis);
           bis.close();
           is.close();
       } catch (IOException e) {
           Log.e("Error getting bitmap", e.toString());
       }
       return bm;
   }
   public View getView(int position, View view, ViewGroup parent) {
       LayoutInflater inflater = context.getLayoutInflater();
       View rowView = inflater.inflate(R.layout.listview, null, true);
       TextView timeView = (TextView) rowView.findViewById(R.id.dateTime);
       TextView conditionView = (TextView) rowView.findViewById(R.id.condition);
       TextView tempView = (TextView) rowView.findViewById(R.id.temp);
       TextView humidityView = (TextView) rowView.findViewById(R.id.humidity);
       ImageView imageView = (ImageView) rowView.findViewById(R.id.icon);
       timeView.setText(time[position]);
       conditionView.setText(condition[position]);
       tempView.setText(temp[position]);
       humidityView.setText(humidity[position]);
       imageView.setImageBitmap(getImageBitmap(url[position]));
       return rowView;  
   }  
   

   }

3. MyBgTask.java

   public class MyBgTask extends AsyncTask<Void, Void, Void> {
   String[] timeArray;
   String[] conditionArray;
   String[] tempArray;
   String[] humidityArray;
   String[] urls;
   public String[] getTimeArray() {
       return timeArray;
   }
   public String[] getConditionArray() {
       return conditionArray;
   }
   public String[] getTempArray() {
       return tempArray;
   }
   public String[] getHumidityArray() {
       return humidityArray;
   }
   public String[] getUrls() {
       return urls;
   }
   @Override
   protected Void doInBackground(Void... params) {
       try {
           // Get User Current Location
           String geoURL = "http://api.wunderground.com/api/56419d324b9bf190/geolookup/q/autoip.json";
           URL url = new URL(geoURL);
           HttpURLConnection request = (HttpURLConnection) url.openConnection();
           request.connect();
           request.getContent();
           JsonParser geo_jp = new JsonParser();
           JsonElement geo_root = geo_jp.parse(new InputStreamReader((InputStream) request.getContent()));
           JsonObject geo_rootobj = geo_root.getAsJsonObject();
           String city = geo_rootobj.get("location").getAsJsonObject().get("city").getAsString();
           String state = geo_rootobj.get("location").getAsJsonObject().get("state").getAsString();
           String zip = geo_rootobj.get("location").getAsJsonObject().get("zip").getAsString();
           // Invoke hourly weather forcast with user's current location
           String forecastURL = "http://api.wunderground.com/api/56419d324b9bf190/conditions/hourly/forecast/q/" + zip + ".json";
           URL furl = new URL(forecastURL);
           HttpURLConnection forecastRequest = (HttpURLConnection) furl.openConnection();
           forecastRequest.connect();
           forecastRequest.getContent();
           JsonParser forecast_jp = new JsonParser();
           JsonElement forecast_root = forecast_jp.parse(new InputStreamReader((InputStream) request.getContent()));
           JsonArray forecast_array = forecast_root.getAsJsonObject().get("hourly_forcast").getAsJsonArray();
           for (int hour = 0; hour < forecast_array.size(); hour++) {
               String month = forecast_array.get(hour).getAsJsonObject().
                       get("FCTTIME").getAsJsonObject().
                       get("mon_abbrev").getAsString();
               String monthDay = forecast_array.get(hour).getAsJsonObject().
                       get("FCTTIME").getAsJsonObject().
                       get("mday_padded").getAsString();
               String time = forecast_array.get(hour).getAsJsonObject().
                       get("FCTTIME").getAsJsonObject().
                       get("civil").getAsString();
               String dateAndtime = month + " " + monthDay + " " + time;
               String condition = forecast_array.get(hour).getAsJsonObject().
                       get("condition").getAsString();
               String temp = forecast_array.get(hour).getAsJsonObject().
                       get("temp").getAsJsonObject().
                       get("english").getAsString();
               String humidity = forecast_array.get(hour).getAsJsonObject().
                       get("humidity").getAsString();
               String icon_url = forecast_array.get(hour).getAsJsonObject().
                       get("icon_url").getAsString();
               timeArray[hour] = dateAndtime;
               conditionArray[hour] = condition;
               tempArray[hour] = temp;
               humidityArray[hour] = humidity;
               urls[hour] = icon_url;
           }
   
       } catch (IOException e) {
           Log.e("ERROR", e.toString());
       }
       return null;
   }
   protected void onPostExecute(Void... params) {
   }
   }
   

4. listView.xml

   <ImageView
       android:id="@+id/icon"
       android:layout_width="60dp"
       android:layout_height="60dp"
       android:padding="5dp" />
   <LinearLayout android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:orientation="vertical">
       <TextView
           android:id="@+id/dateTime"
           android:layout_width="wrap_content"
           android:layout_height="wrap_content"
           android:textAppearance="?android:attr/textAppearanceMedium"
           android:layout_marginLeft="10dp"
           android:layout_marginTop="5dp"
           android:padding="2dp"
           android:textColor="#33CC33"
           android:text="@string/dateTime" />
       <TextView
           android:id="@+id/condition"
           android:layout_width="wrap_content"
           android:layout_height="wrap_content"
           android:text="@string/condition"
           android:layout_marginLeft="10dp"/>
       <TextView
           android:id="@+id/temp"
           android:layout_width="wrap_content"
           android:layout_height="wrap_content"
           android:text="@string/temp"
           android:layout_marginLeft="10dp" />
       <TextView
           android:id="@+id/humidity"
           android:layout_width="wrap_content"
           android:layout_height="wrap_content"
           android:text="@string/humidity"
           android:layout_marginLeft="10dp" />
   </LinearLayout>
   

5. activity_main.xml

   <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
   android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
   android:paddingRight="@dimen/activity_horizontal_margin"
   android:paddingTop="@dimen/activity_vertical_margin"
   android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".main">
   <ListView
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:id="@+id/listView"
       android:clickable="false"
       android:layout_alignParentLeft="true"
       android:layout_alignParentStart="true" >
   
   </ListView>
   

Answer 1

根据我所看到的，程序崩溃是因为time在这一行是null：

public CustomListAdapter(Activity context, String[] time, String[] condition, String[] temp, String[] humidity, String[] url){
    super(context, R.layout.listview, time);
    ...
}

这是因为，正如@codeMagic在评论中所说，您错误地使用了AsyncTask类。以下代码在您的onCreate方法中

MyBgTask asyncTask = new MyBgTask();
CustomListAdapter adapter = new CustomListAdapter(this, asyncTask.getTimeArray(), asyncTask.getConditionArray(),
                                asyncTask.getTempArray(), asyncTask.getHumidityArray(), asyncTask.getUrls());

创建AsyncTask，但不创建execute()。当您调用getTimeArray()时，它会返回timeArray的值，这是默认初始化的null值。

大体上，你需要

• 执行AsyncTask
• 任务完成后更新ArrayListAdapter