parcelable classes app crashing

嗨我的應用程序出現問題。我的課程起初是可序列化的，因爲我將它們改爲parcelable並出現問題。問題是當我瀏覽應用程序內部的片段時，它有時會崩潰。請希望在這裏我可以得到一些幫助這裏是我的2類和logcat消息。感謝您的關注parcelable classes app crashing

City.java

public class City implements Parcelable { 
    private String code; 
    private String name; 

    private List<CityWeather> weathers ; 


    public City() { 
     super(); 
    } 
    public String getName() { 
     return name; 
    } 
    public void setName(String name) { 
     this.name = name; 
    } 
    public String getCode() { 
     return code; 
    } 
    public void setCode(String code) { 
     this.code = code; 
    } 
    public List<CityWeather> getWeathers() { 
     if(weathers == null) { 
      weathers = new ArrayList<CityWeather>(); 
     } 
     return weathers; 
    } 
    public void addCityWeather(CityWeather w) { 
     getWeathers().add(w); 
    } 

    public void addCityWeathers(List<CityWeather> w) { 
     getWeathers().addAll(w); 
    } 



    public City(Parcel in) { 
     readFromParcel(in); 
    } 

    @Override 
    public void writeToParcel(Parcel dest, int flags) { 
     dest.writeString(code); 
     dest.writeString(name); 
     dest.writeTypedList(weathers); 
    } 

    private void readFromParcel(Parcel in) { 
     code = in.readString(); 
     name = in.readString(); 
     in.readTypedList(weathers, CityWeather.CREATOR); 
    } 

    public static final Parcelable.Creator<City> CREATOR = new Parcelable.Creator<City>() { 
     public City createFromParcel(Parcel in) { 
      return new City(in); 
     } 

     public City[] newArray(int size) { 
      return new City[size]; 
     } 
    }; 


    @Override 
    public int describeContents() { 
     // TODO Auto-generated method stub 
     return 0; 
    } 
}

CityWeather.java

public class CityWeather implements Parcelable { 


    private String date; 
    private String weatherDescription; 
    private int weatherCode; 
    private String currentTemperature; 
    private String minTemperature; 
    private String maxTemperature; 
    private String humadity; 
    private String wind; 
    private String day; 
    private String temperatureUnit; 



    public String getTemperatureUnit(){ 
     return temperatureUnit; 
    } 
    public void setTemperatureUnit(String temperatureUnit){ 
     this.temperatureUnit = temperatureUnit; 
    } 
    public String getDate() { 
     return date; 
    } 
    public void setDate(String date) { 
     this.date = date; 
    } 
    public String getWeatherDescription() { 
     return weatherDescription; 
    } 
    public void setWeatherDescription(String weatherDescription) { 
     this.weatherDescription = weatherDescription; 
    } 
    public int getWeatherCode() { 
     return weatherCode; 
    } 
    public void setWeatherCode(int weatherCode) { 
     this.weatherCode = weatherCode; 
    } 
    public String getCurrentTemperature() { 
     return currentTemperature; 
    } 
    public void setCurrentTemperature(String currentTemperature) { 
     this.currentTemperature = currentTemperature; 
    } 
    public String getMinTemperature() { 
     return minTemperature; 
    } 
    public void setMinTemperature(String minTemperature) { 
     this.minTemperature = minTemperature; 
    } 
    public String getMaxTemperature() { 
     return maxTemperature; 
    } 
    public void setMaxTemperature(String maxTemperature) { 
     this.maxTemperature = maxTemperature; 
    } 
    public String getHumadity() { 
     return humadity; 
    } 
    public void setHumadity(String humadity) { 
     this.humadity = humadity; 
    } 
    public String getWind() { 
     return wind; 
    } 
    public void setWind(String wind) { 
     this.wind = wind; 
    } 
    public String getDay() { 
     return day; 
    } 
    public void setDay(String day) { 
     this.day = day; 
    } 



    protected CityWeather(Parcel in) { 
     date = in.readString(); 
     weatherDescription = in.readString(); 
     weatherCode = in.readInt(); 
     currentTemperature = in.readString(); 
     minTemperature = in.readString(); 
     maxTemperature = in.readString(); 
     humadity = in.readString(); 
     wind = in.readString(); 
     day = in.readString(); 
     temperatureUnit = in.readString(); 
    } 

    public CityWeather() { 
     // TODO Auto-generated constructor stub 
    } 
    @Override 
    public int describeContents() { 
     return 0; 
    } 

    @Override 
    public void writeToParcel(Parcel dest, int flags) { 
     dest.writeString(date); 
     dest.writeString(weatherDescription); 
     dest.writeInt(weatherCode); 
     dest.writeString(currentTemperature); 
     dest.writeString(minTemperature); 
     dest.writeString(maxTemperature); 
     dest.writeString(humadity); 
     dest.writeString(wind); 
     dest.writeString(day); 
     dest.writeString(temperatureUnit); 
    } 

    @SuppressWarnings("unused") 
    public static final Parcelable.Creator<CityWeather> CREATOR = new Parcelable.Creator<CityWeather>() { 
     @Override 
     public CityWeather createFromParcel(Parcel in) { 
      return new CityWeather(in); 
     } 

     @Override 
     public CityWeather[] newArray(int size) { 
      return new CityWeather[size]; 
     } 
    }; 
}

和logcat的消息

02-16 17:30:23.014: E/AndroidRuntime(15818): FATAL EXCEPTION: main 
02-16 17:30:23.014: E/AndroidRuntime(15818): java.lang.RuntimeException: Unable to start activity ComponentInfo{ge.mobility.weather/ge.mobility.weather.activity.MainActivity}: java.lang.NullPointerException 
02-16 17:30:23.014: E/AndroidRuntime(15818): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2355) 
02-16 17:30:23.014: E/AndroidRuntime(15818): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2391) 
02-16 17:30:23.014: E/AndroidRuntime(15818): at android.app.ActivityThread.access$600(ActivityThread.java:151) 
02-16 17:30:23.014: E/AndroidRuntime(15818): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1335) 
02-16 17:30:23.014: E/AndroidRuntime(15818): at android.os.Handler.dispatchMessage(Handler.java:99) 
02-16 17:30:23.014: E/AndroidRuntime(15818): at android.os.Looper.loop(Looper.java:155) 02-16 17:30:23.014: E/AndroidRuntime(15818): at android.app.ActivityThread.main(ActivityThread.java:5520) 
02-16 17:30:23.014: E/AndroidRuntime(15818): at java.lang.reflect.Method.invokeNative(Native Method) 
02-16 17:30:23.014: E/AndroidRuntime(15818): at java.lang.reflect.Method.invoke(Method.java:511) 
02-16 17:30:23.014: E/AndroidRuntime(15818): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1029) 
02-16 17:30:23.014: E/AndroidRuntime(15818): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:796) 
02-16 17:30:23.014: E/AndroidRuntime(15818): at dalvik.system.NativeStart.main(Native Method) 
02-16 17:30:23.014: E/AndroidRuntime(15818): Caused by: java.lang.NullPointerException 
02-16 17:30:23.014: E/AndroidRuntime(15818): at android.os.Parcel.readTypedList(Parcel.java:1754) 
02-16 17:30:23.014: E/AndroidRuntime(15818): at ge.mobility.weather.entity.City.readFromParcel(City.java:62) 
02-16 17:30:23.014: E/AndroidRuntime(15818): at ge.mobility.weather.entity.City.(City.java:49) 
02-16 17:30:23.014: E/AndroidRuntime(15818): at ge.mobility.weather.entity.City$1.createFromParcel(City.java:67) 
02-16 17:30:23.014: E/AndroidRuntime(15818): at ge.mobility.weather.entity.City$1.createFromParcel(City.java:1) 
02-16 17:30:23.014: E/AndroidRuntime(15818): at android.os.Parcel.readParcelable(Parcel.java:2108)

來源

2014-02-16 user3314123

的NPE可能是由於w ^如果未初始化天氣列表，則會調用createFromParcel。

嘗試將

private List<CityWeather> weathers;

與

private List<CityWeather> weathers = new ArrayList<CityWeather>();

來源

2014-02-16 14:22:21 Wizche

我想天氣取而代之的是null..You應該確保列表中的數據編出對象之前instantied。

private void readFromParcel(Parcel in) { 
    code = in.readString(); 
    name = in.readString(); 
    in.readTypedList(weathers, CityWeather.CREATOR); //HERE IT FAILS 
}

嘗試這種

private void readFromParcel(Parcel in) { 
    code = in.readString(); 
    name = in.readString(); 
    if(weathers == null){ 
     weathers = new ArrayList<CityWeather>(); 
    } 
    in.readTypedList(weathers, CityWeather.CREATOR); 
}

來源

2014-02-16 14:22:50 simekadam

替代方法是通過使用GSON到一個目的是一個JSONObject轉換。

初始活性

Intent activity = new Intent(MyActivity.this,NextActivity.class); 
activity.putExtra("myObject", new Gson().toJson(myobject); 
startActivity(activity);

下一個活動

Sting jsonMyObject; 
Bundle extras = getIntent().getExtras(); 
if (extras != null) { 
    jsonMyObject = extras.getString("myObject"); 
} 
MyObject myObject = new Gson().fromJson(jsonMyObject, MyObject.class);

來源

2014-02-16 14:54:05 Megamind

這怎麼棧對parcelable在性能比較方面？ – simekadam

parcelable classes app crashing

回答

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