當我從 MainActivity 更新 LoginViewModel 中的 User 屬性時，我的 UI 沒有改變。（卡在這個問題上 2 天了，找不到解決方案）我的 User 類擴展了 BaseObservable（添加了 @Bindable 和 notificationPropertyChanged()），但我不知道我還應(yīng)該做什么。這些是課程：用戶：public class User extends BaseObservable { protected String userName; protected String lastName; public User(String userName, String lastName) { this.userName = userName; this.lastName = lastName; notifyPropertyChanged(BR._all); } @Bindable public String getUserName() { return userName; } public void setUserName(String userName) { this.userName = userName; notifyPropertyChanged(BR.userName); } @Bindable public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; notifyPropertyChanged(BR.lastName); }}視圖模型：public class LoginViewModel extends ViewModel { private User user; public LoginViewModel() { user = new User("Pero","Peric"); } public User getUser() { return user; } public void setUser(User user) { this.user = user; } public String getUserName() { return user.getUserName(); } public void setUserName(String userName) { user.setUserName(userName); } public String getLastName() { return user.getLastName(); } public void setLastName(String lastName) { user.setUserName(lastName); }}
1 回答
蝴蝶刀刀
TA貢獻1801條經(jīng)驗 獲得超8個贊
問題是我：
a)hadnt implement Observerble interface to ViewModel(I susspect that DataBinding
adds/removes his listener through that methods)
b)made get methods @Bindable,and notify notifyPropertyChanged() in seters,
c)add property in ViewModel of type PropertyChangeRegistry
d)add notifyPropertyChanged(int fieldID) method
視圖模型：
public class LoginViewModel extends ViewModel implements Observable {
private User user;
private PropertyChangeRegistry callbacks;
public LoginViewModel() {
user = new User("Karlo","maricevic");
callbacks = new PropertyChangeRegistry();
}
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
@Bindable
public String getUserName()
{
return user.getUserName();
}
public void setUserName(String userName)
{
user.setUserName(userName);
notifyPropertyChanged(BR.userName);
}
@Bindable
public String getLastName()
{
return user.getLastName();
}
public void setLastName(String lastName)
{
user.setUserName(lastName);
}
@Override
public void addOnPropertyChangedCallback(OnPropertyChangedCallback callback) {
callbacks.add(callback);
}
@Override
public void removeOnPropertyChangedCallback(OnPropertyChangedCallback callback) {
//callbacks.remove(callback);
}
void notifyPropertyChanged(int fieldId)
{
callbacks.notifyCallbacks(this,fieldId,null);
}
}
PS：在這個例子的小實驗之后，你不需要用戶擴展 BaseObservable 來從 ViewModel 更新 UI
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