我正在保存我ArrayLists
的. 我这样做如下:SharedPreferences
onPause
MainActivity
TinyDB tinyDB = new TinyDB(activity);
ArrayList<Object> saveUserList = new ArrayList<>();
for (User user : UsersArrayList.getInstance().getUsersList()) {
saveUserList.add(user);
}
tinyDB.putListObject("userList", saveUserList);
并按如下方式调用我的更新onCreateView
:
TinyDB tinyDB = new TinyDB(activity);
ArrayList<User> userList = new ArrayList<>();
for (Object object : tinyDB.getListObject("userList", User.class)) {
userList.add((User) object);
}
for (User user : userList) {
if (!UsersArrayList.getInstance().getUsersList().contains(user)) {
UsersArrayList.getInstance().getUsersList().add(user);
}
}
然而.contains(user)
,总是返回 false 并不断将相同的对象添加到我的数组中。而且我只希望添加一次不在其中的内容。为什么 contains 运算符在这里无法正常工作?
这是ArrayList
我保存日期并希望更新的课程:
public class UsersArrayList {
public ArrayList<User> usersList;
private UsersArrayList() {
usersList = new ArrayList<User>();
}
public ArrayList<User> getUsersList() {
return usersList;
}
private static UsersArrayList instance;
public static UsersArrayList getInstance() {
if (instance == null) instance = new UsersArrayList();
return instance;
}
}