如您所见，这是针对用户和管理员的登录活动。用户登录工作正常，但是当我尝试登录 admin 时，应用程序在 onDataChange 处引发错误。
错误：
com.google.firebase.database.DatabaseException: Failed to convert value of type java.lang.Long to String
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.convertString(CustomClassMapper.java:426)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.deserializeToClass(CustomClassMapper.java:217)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.deserializeToType(CustomClassMapper.java:179)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.access$100(CustomClassMapper.java:48)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper$BeanMapper.deserialize(CustomClassMapper.java:593)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper$BeanMapper.deserialize(CustomClassMapper.java:563)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.convertBean(CustomClassMapper.java:433)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.deserializeToClass(CustomClassMapper.java:232)
at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.convertToCustomClass(CustomClassMapper.java:80)
at com.google.firebase.database.DataSnapshot.getValue(DataSnapshot.java:203)
at com.example.cardview.LoginActivity$4.onDataChange(LoginActivity.java:128)
at com.google.firebase.database.Query$1.onDataChange(Query.java:191)
at com.google.firebase.database.core.ValueEventRegistration.fireEvent(ValueEventRegistration.java:75)
at com.google.firebase.database.core.view.DataEvent.fire(DataEvent.java:63)
at com.google.firebase.database.core.view.EventRaiser$1.run(EventRaiser.java:55)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:224)
at android.app.ActivityThread.main(ActivityThread.java:7147)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:511)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:876)
public class LoginActivity extends AppCompatActivity {
private EditText InputPhoneNumber, InputPassword;
private Button LoginButton;
private ProgressDialog loadingBar;
private TextView AdminLink, NotAdminLink;
private String parentDbName = "Users";
private CheckBox chkBoxRememberMe;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
LoginButton = (Button) findViewById(R.id.login_btn);
InputPassword = (EditText) findViewById(R.id.login_password_input);
InputPhoneNumber = (EditText) findViewById(R.id.login_phone_number_input);
AdminLink = (TextView) findViewById(R.id.admin_panel_link);
NotAdminLink = (TextView) findViewById(R.id.not_admin_panel_link);
loadingBar = new ProgressDialog(this);
chkBoxRememberMe = (CheckBox) findViewById(R.id.remember_me_chkb);
Paper.init(this);
LoginButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view)
{
LoginUser();
}
});
AdminLink.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view)
{
LoginButton.setText( "Login Admin" );
AdminLink.setVisibility( View.INVISIBLE );
NotAdminLink.setVisibility( View.VISIBLE );
parentDbName = "Admins";
}
});
NotAdminLink.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view)
{
LoginButton.setText( "Login" );
AdminLink.setVisibility( View.VISIBLE );
NotAdminLink.setVisibility( View.INVISIBLE );
parentDbName = "Users";
}
});
}
private void LoginUser()
{
String phone = InputPhoneNumber.getText().toString();
String password = InputPassword.getText().toString();
if (TextUtils.isEmpty(phone))
{
Toast.makeText(this, "Please write your phone number...", Toast.LENGTH_SHORT).show();
}
else if (TextUtils.isEmpty(password))
{
Toast.makeText(this, "Please write your password...", Toast.LENGTH_SHORT).show();
}
else
{
loadingBar.setTitle("Login Account");
loadingBar.setMessage("Please wait, while we are checking the credentials.");
loadingBar.setCanceledOnTouchOutside(false);
loadingBar.show();
AllowAccessToAccount(phone, password);
}
}
private void AllowAccessToAccount(final String phone, final String password)
{
if(chkBoxRememberMe.isChecked())
{
Paper.book().write(Prevalent.UserPhoneKey, phone);
Paper.book().write(Prevalent.UserPasswordKey, password);
}
final DatabaseReference RootRef;
RootRef = FirebaseDatabase.getInstance().getReference();
RootRef.addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot)
{
if (dataSnapshot.child(parentDbName).child(phone).exists())
{
Users usersData = dataSnapshot.child(parentDbName).child(phone).getValue(Users.class);
if (usersData.getPhone().equals(phone))
{
if (usersData.getPassword().equals(password))
{
if (parentDbName.equals("Admins"))
{
Toast.makeText(LoginActivity.this, "Welcome Admin, You are logged in Successfully...", Toast.LENGTH_SHORT).show();
loadingBar.dismiss();
Intent intent = new Intent(LoginActivity.this, AdminAddNewProductActivity.class);
Prevalent.currentOnlineUser = usersData;
startActivity(intent);
}
else if(parentDbName.equals("Users"))
{
Toast.makeText(LoginActivity.this, "User logged in Successfully...", Toast.LENGTH_SHORT).show();
loadingBar.dismiss();
Intent intent = new Intent(LoginActivity.this, HomeActivity.class);
Prevalent.currentOnlineUser = usersData;
startActivity(intent);
}
}
else
{
loadingBar.dismiss();
Toast.makeText(LoginActivity.this, "Password is incorrect.", Toast.LENGTH_SHORT).show();
}
}
}
else
{
Toast.makeText(LoginActivity.this, "Account with this " + phone + " number do not exists.", Toast.LENGTH_SHORT).show();
loadingBar.dismiss();
}
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
}
}
答案 0 :(得分：2)
看起来数据库在其中一个属性中包含一个数值，但您的 Users 类声明了与 String 相同的属性。 Firebase 不会在此处为您执行自动转换，因为它会导致回写数据库时出现问题。
根据所提供的信息无法确定是哪个特定属性导致了问题，但如果将数据库中的 JSON 与 Java Users 类进行比较，应该很容易发现。