Android 在共享首选项中存储自定义数组列表

我想在共享首选项中存储自定义数组列表，以便下次打开应用程序时可以读取该列表。 我看了很多教程和答案，但我不能真正理解它

list_addr.java

public class list_addr {

public String title;
public String detail;


public list_addr( String title, String detail) {
    super();

    this.title = title;
    this.detail=detail;

}

public String getTitle() {
    return title;
}
public void setTitle(String title) {
    this.title = title;
}
public String getDetail() {
    return detail;
}
public void setDetail(String detail) {
    this.detail = detail;
}


@Override
public String toString() {
    return title + "\n" ;
}

}

list_adapter.java

enterpublic class list_addr_adapter extends ArrayAdapter<list_addr> {

Context context;
int layoutResourceId;



public list_addr_adapter(Context context, int layoutResourceId, List<list_addr> items) {
    super(context, layoutResourceId, items);
    this.layoutResourceId = layoutResourceId;
    this.context = context;
    //  this.listener=callback;
}

/*private view holder class*/
private class ViewHolder {

    TextView txtTitle;
    TextView txtDetail;
    ImageView imageview;
    CheckBox checkbox;

}
ViewHolder holder = null;

public View getView(final int position, View convertView, ViewGroup parent) {
    final list_addr lists = getItem(position);
    final int pos=position;


    LayoutInflater mInflater = (LayoutInflater) context
            .getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
    if (convertView == null) {
        convertView = mInflater.inflate(R.layout.items_sav_addr2, null);
        holder = new ViewHolder();
        holder.txtTitle = (TextView) convertView.findViewById(R.id.textTitle);
        holder.txtDetail = (TextView) convertView.findViewById(R.id.detail);
        holder.imageview = (ImageView) convertView.findViewById(R.id.imageview);
        holder.checkbox=(CheckBox)convertView.findViewById(R.id.chkitem);


        convertView.setTag(holder);
    } else
        holder = (ViewHolder) convertView.getTag();






    holder.txtTitle.setText(lists.getTitle());
    holder.txtDetail.setText(lists.getDetail());

        return convertView;
    }

}

---

只能在共享首选项中保存基元类型。如果需要保存ArrayList，则可以将其保存为逗号分隔的字符串。在获取此字符串时，请在此字符串上使用split（“，”），您将得到该字符串的字符串[]

如果你想保存一个对象列表，我建议你使用一个Singleton类。这是Singelton类的示例。如果您需要，请尝试此选项

public class ReferenceWrapper {
private Context context;
private static ReferenceWrapper wrapper;
private ArrayList<Object> list;

private ReferenceWrapper(Context context) {
    this.context = context;
}

public static ReferenceWrapper getInstance(Activity activity) {
    if (wrapper == null) {
        wrapper = new ReferenceWrapper(activity);
    }
    return wrapper;
}


public ArrayList<Object> getList() {
    return list;
}

public void setList(ArrayList<Object> list) {
    this.list = list;
}

在任何活动中都能得到它

ReferenceWrapper wrapper=ReferenceWrapper.getInstance(MainActivity.this);
ArrarList<Object> list= wrapper.getList(yourArrarlist);

ReferenceWrapper=ReferenceWrapper.getInstance（MainActivity.this）；
ArrarList list=wrapper.getList（您的ArrarList）；

它将返回与您最近保存的ArrayList相同的列表。因为它只创建了一个对象

---

。请告诉我在共享首选项中保存arraylist是否有帮助。请执行以下操作

 // Create List of address that you want to save
    ArrayList addressList = new ArrayList();
    addressList.add(new list_addr());
   addressList.add(new list_addr());
    SharedPreferences prefs = getSharedPreferences("address", Context.MODE_PRIVATE);
    //save the user list to preference
    Editor editor = prefs.edit();
    try {
    editor.putString("addressList", ObjectSerializer.serialize(addressList));
    } catch (IOException e) {
    e.printStackTrace();
    }
    editor.commit();

然后使用以下命令检索arraylist

ArrayList addressList = new ArrayList();
// Load address List from preferences
SharedPreferences prefs = getSharedPreferences("address", Context.MODE_PRIVATE);
try {
addressList = (ArrayList) ObjectSerializer.deserialize(prefs.getString("addressList", ObjectSerializer.serialize(new ArrayList())));
} catch (IOException e) {
e.printStackTrace();
}

这是objectSerializer类的链接

---

答案是关于在

文件中写入对象，而不是
共享引用。希望这能有所帮助

    try {
        ArrayList<List_addr> addrList = new ArrayList<>();
        addrList.add(new List_addr("Bangalore", "Its a City"));
        addrList.add(new List_addr("Delhi", "Its also a City"));

        //write object into a file
        FileOutputStream fos = openFileOutput("addrList", Context.MODE_PRIVATE);
        ObjectOutputStream oos = new ObjectOutputStream(fos);
        oos.writeObject(addrList);
        oos.close();

        //read object from the file
        FileInputStream fis = openFileInput("addrList");
        ObjectInputStream ois = new ObjectInputStream(fis);
        ArrayList<List_addr> readAddrList = (ArrayList<List_addr>) ois.readObject();
        ois.close();

        for (List_addr address : readAddrList) {
            Log.i("TAG", "Name " + address.getTitle() + " City " + address.getDetail());
        }
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }

试试看{
ArrayList addrList=新的ArrayList（）；
addrList.add（新列表地址（“班加罗尔”，“它是一座城市”）；
addrList.add（新德里，它也是一个城市）；
//将对象写入文件
FileOutputStream fos=openFileOutput（“addrList”，Context.MODE\u PRIVATE）；
ObjectOutputStream oos=新的ObjectOutputStream（fos）；
oos.writeObject（addrList）；
oos.close（）；
//从文件中读取对象
FileInputStream fis=openFileInput（“addrList”）；
ObjectInputStream ois=新ObjectInputStream（fis）；
ArrayList readAddrList=（ArrayList）ois.readObject（）；
ois.close（）；
用于（列表地址：readAddrList）{
Log.i（“TAG”，“Name”+address.getTitle（）+“City”+address.getDetail（））；
}
}catch（filenotfounde异常）{
e、 printStackTrace（）；
}捕获（IOE异常）{
e、 printStackTrace（）；
}catch（classnotfounde异常）{
e、 printStackTrace（）；
}

重要提示：请注意@MeetTitan回复评论
 
步骤1：
         Step 1:

           Put string array set into the shared preference.
           pref.putStringSet(String key, Set<String> values);

         Step 2:

           Convert array list of pojo into set.
           Set<String> set = new HashSet<String>(list);

         Set 3:

           Retrive using the getStringSet.

将字符串数组集放入共享首选项。
pref.putStringSet（字符串键，设置值）；
步骤2：
将pojo的数组列表转换为集合。
Set Set=新哈希集（列表）；
第三组：
使用getStringSet检索。
您是否尝试过将其保存在共享首选项中，因为您的代码没有显示任何一行保存内容code@VivekMishra不，我没有，因为我不理解这个方法。然后谷歌将arraylist存储在shared中preferences@VivekMishra我就是这么说的，让
list\u addr
实现可序列化，并使用
ObjectOutputStream
和
ByteArrayOutputStream
将该数组列表序列化为字节数组，然后存储字节数组，并在使用时将其反序列化回列表。如果您感到困惑，我可以添加一个代码示例。如何准确地使用这个类？
    try {
        ArrayList<List_addr> addrList = new ArrayList<>();
        addrList.add(new List_addr("Bangalore", "Its a City"));
        addrList.add(new List_addr("Delhi", "Its also a City"));

        //write object into a file
        FileOutputStream fos = openFileOutput("addrList", Context.MODE_PRIVATE);
        ObjectOutputStream oos = new ObjectOutputStream(fos);
        oos.writeObject(addrList);
        oos.close();

        //read object from the file
        FileInputStream fis = openFileInput("addrList");
        ObjectInputStream ois = new ObjectInputStream(fis);
        ArrayList<List_addr> readAddrList = (ArrayList<List_addr>) ois.readObject();
        ois.close();

        for (List_addr address : readAddrList) {
            Log.i("TAG", "Name " + address.getTitle() + " City " + address.getDetail());
        }
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }

         Step 1:

           Put string array set into the shared preference.
           pref.putStringSet(String key, Set<String> values);

         Step 2:

           Convert array list of pojo into set.
           Set<String> set = new HashSet<String>(list);

         Set 3:

           Retrive using the getStringSet.