Java 如何转换列表<;定制类>;到ArrayList<;定制类>;反之亦然?
我有一个Java 如何转换列表<;定制类>;到ArrayList<;定制类>;反之亦然?,java,android,list,arraylist,sharedpreferences,Java,Android,List,Arraylist,Sharedpreferences,我有一个CustomClass,它是Bean/Model/Pojo,用于从Json保存自定义Obejcts。我想在SharedReference中保存我的CustomClass的ArrayList,并在特殊场景中检索它。我找到了一种将其存储在SharedReference中的方法!正确答案由SpyZip 我可以存储和检索列表,但我想存储和检索数组列表 下面是一个片段,显示了我如何在SharedReference中存储和检索值: // This method will save custo
CustomClass
,它是Bean/Model/Pojo
,用于从Json保存自定义Obejcts。我想在SharedReference
中保存我的CustomClass
的ArrayList
,并在特殊场景中检索它。我找到了一种将其存储在SharedReference
中的方法!正确答案由SpyZip
我可以存储和检索列表
,但我想存储和检索数组列表
下面是一个片段,显示了我如何在SharedReference
中存储和检索值:
// This method will save custom class ArrayList<Bean>
public void saveUserFavouriteStations(
ArrayList<RadioStationBean> radioStation) {
FavouriteStationHolder = this.getSharedPreferences("stations", 0);
Editor editor = FavouriteStationHolder.edit();
Gson gson = new Gson();
String jsonCars = gson.toJson(radioStation);
editor.putString("stations", jsonCars);
System.out.println("Custom ArrayList Saved in App Class");
editor.commit();
}
public ArrayList<RadioStationBean> getUserFavouriteStations() {
FavouriteStationHolder = this.getSharedPreferences("stations", 0);
if (FavouriteStationHolder != null) {
String jsonString = FavouriteStationHolder
.getString("stations", "");
Type type = new TypeToken<List<RadioStationBean>>() {
}.getType();
List<RadioStationBean> carsList = gson.fromJson(jsonString, type);
return carsList;
} else {
return null;
}
}
//此方法将保存自定义类ArrayList
公共void saveUserFavoriteStations(
ArrayList无线电台){
FavoriteStationHolder=this.getSharedReferences(“站点”,0);
Editor=favoriteStationHolder.edit();
Gson Gson=新的Gson();
字符串jsonCars=gson.toJson(radioStation);
putString(“stations”,jsonCars);
System.out.println(“保存在应用程序类中的自定义ArrayList”);
commit();
}
公共阵列列表GetUserFavoriteStations(){
FavoriteStationHolder=this.getSharedReferences(“站点”,0);
if(FavoriteStationHolder!=null){
字符串jsonString=FavoriteStationHolder
.getString(“stations”和“”);
Type Type=new-TypeToken(){
}.getType();
List carsList=gson.fromJson(jsonString,type);
返回车单;
}否则{
返回null;
}
}
是接口的一种特定(基于阵列)实现。因为您应该很少关心底层实现,而且这似乎不是罕见的情况之一,只需将方法签名更改为在参数列表和返回值中使用List
。您只需将java对象转换为字符串,并将该字符串存储在SharedReferences中,在检索数据时将该字符串转换回java对象。使用类型ArrayList获取ArrayList中的数据
String jsonString = FavouriteStationHolder
.getString("stations", "");
Type type = new TypeToken<ArrayList<RadioStationBean>>() {
}.getType();
ArrayList<RadioStationBean> carsList = gson.fromJson(jsonString, type);
String jsonString=FavoriteStationHolder
.getString(“stations”和“”);
Type Type=new-TypeToken(){
}.getType();
ArrayList carsList=gson.fromJson(jsonString,type);
悲哀的是,没有一个解决方案有效,一个列表不能直接转换到ArrayList
,因此,我试图通过解析从gson获得的json,创建一个新的CustomClass对象,并使用for
迭代器,使用以下代码构建一个新的ArrayList,来创建我自己的解决方案
if (FavouriteStationHolder != null) {
String jsonString = FavouriteStationHolder
.getString("stations", "");
System.out.println("json String got in App class-->" + jsonString);
Type type = new TypeToken<List<RadioStationBean>>() {
}.getType();
List<RadioStationBean> stations = gson.fromJson(jsonString, type);
ArrayList<RadioStationBean> stationsList = new ArrayList<RadioStationBean>();
for (int i = 0; i < stations.size(); i++) {
RadioStationBean rBean = new RadioStationBean();
rBean.setAdvertisements(stations.get(i).getAdvertisements());
rBean.setCategories_id(stations.get(i).getCategories_id());
rBean.setCategoy(stations.get(i).getCategoy());
rBean.setDescription(stations.get(i).getDescription());
rBean.setFacebook(stations.get(i).getFacebook());
rBean.setId(stations.get(i).getId());
rBean.setImage_url(stations.get(i).getImage_url());
rBean.setIsDispTrack_Artist(stations.get(i)
.getIsDispTrack_Artist());
rBean.setManager_detail(stations.get(i).getManager_detail());
rBean.setPhone_show(stations.get(i).getPhone_show());
rBean.setPhone_studio(stations.get(i).getPhone_studio());
rBean.setPhone_toll_free(stations.get(i).getPhone_toll_free());
rBean.setPlatform(stations.get(i).getPlatform());
rBean.setStation_image(stations.get(i).getStation_image());
rBean.setStation_manager(stations.get(i).getStation_manager());
rBean.setStation_manager_id(stations.get(i)
.getStation_manager_id());
rBean.setStation_name(stations.get(i).getStation_name());
rBean.setStation_status(stations.get(i).getStation_status());
rBean.setStream_format(stations.get(i).getStream_format());
rBean.setStream_url(stations.get(i).getStream_url());
rBean.setTheme_color(stations.get(i).getTheme_color());
rBean.setTwitter(stations.get(i).getTwitter());
rBean.setWeb_portal(stations.get(i).getWeb_portal());
stationsList.add(rBean);
}
System.out.println("Custom ArrayList Retrieved in App Class"
+ stationsList.get(0).getDescription());
return stationsList;
}
if(FavoriteStationHolder!=null){
字符串jsonString=FavoriteStationHolder
.getString(“stations”和“”);
System.out.println(“应用程序类-->中得到的json字符串”+jsonString);
Type Type=new-TypeToken(){
}.getType();
List stations=gson.fromJson(jsonString,type);
ArrayList StationList=新建ArrayList();
对于(int i=0;i
非常感谢大家努力帮助我并开始下载投票者和复印机ArrayList carsList=gson.fromJson(jsonString,type);这又如何呢?创建无用对象的原因可能是重复的,只需返回return gson.fromJson(jsonString,type)
@dnozay不是重复的,如果你清楚地阅读问题@ρ∑ρρρK,如果你仔细阅读我的问题,我想返回ArrayList,而不是gson responseNullPointer,但是我能够打印jsonString,数据是正确的,唯一的问题是转换列表我的意思是在保存和检索时使用ArrayList。这有用吗?