每次阅读时，Firebase数据库都会返回空值 [英] Firebase Database returns null every time while reading
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问题描述
我有一个类从我的数据库中读取数据，但总是返回 null 。
这里是java file
public class UserActivity extends AppCompatActivity {
TextView textView;
私有FirebaseDatabase mFirebaseDatabase;
private FirebaseAuth mAuth;
私有FirebaseAuth.AuthStateListener mAuthListener;
私人DatabaseReference myRef;
private String userID;
private String TAG =hifiwi;
@Override
protected void onCreate（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）;
setContentView（R.layout.activity_user）;
textView =（TextView）findViewById（R.id.textView）;
////////////////////////////////////////// ////////////////////
mAuth = FirebaseAuth.getInstance（）;
mFirebaseDatabase = FirebaseDatabase.getInstance（）;
myRef = mFirebaseDatabase.getReference（）;
FirebaseUser user = mAuth.getCurrentUser（）;
userID = user.getUid（）;
mAuthListener = new FirebaseAuth.AuthStateListener（）{
@Override $ b $ public void onAuthStateChanged（@NonNull FirebaseAuth firebaseAuth）{
FirebaseUser user = mAuth.getCurrentUser（）;
if（user！= null）{
Toast.makeText（UserActivity.this，用user.getEmail（），Toast.LENGTH_SHORT）.show（）;
} else {
Toast.makeText（UserActivity.this，成功退出...，Toast.LENGTH_SHORT）.show（）;
}
}
};
myRef.addValueEventListener（new ValueEventListener（）{
@Override $ b $ public void onDataChange（DataSnapshot dataSnapshot）{
showData（dataSnapshot）;
}
@Override
public void onCancelled（DatabaseError databaseError）{
$ b}
}）;
////////////////////////////////////// /////////////////////////
}
private void showData（ （DataSnapshot ds：dataSnapshot.getChildren（））{
UserInformation uInfo = new UserInformation（）;
uInfo.setEmail（ds.child（userID）.getValue（UserInformation.class）.getEmail（））;
uInfo.setName（ds.child（userID）.getValue（UserInformation.class）.getName（））;
uInfo.setPassword（ds.child（userID）.getValue（UserInformation.class）.getPassword（））;
uInfo.setPhoneno（ds.child（userID）.getValue（UserInformation.class）.getPhoneno（））;
Log.i（TAG，+ uInfo.getEmail（））; //总是返回null
Log.i（TAG，+ uInfo.getName（））; //总是返回null
Log.i（TAG，+ uInfo.getPassword（））; //总是返回null
Log.i（TAG，+ uInfo.getPhoneno（））; //总是返回null
$ b $覆盖b $ b保护无效onStart（）{
super.onStart（）;
mAuth.addAuthStateListener（mAuthListener）;
@Override
protected void onStop（）{
super.onStop（）;
mAuth.removeAuthStateListener（mAuthListener）;
$ p $日志语句总是返回 null
$ b 这是我在 t2-login （项目名称）下的数据库结构。
$ $ $
$用户$ {
8dQ8unnqQXa69nkxUFKrcgiTM3S2：{
emailuser：sam @ gmail.com，
mobileUser：1234567899，
nameuser：sam，
passworduser：sammypp
}，
DIMBAk4CHZdWGbxN9kPESwIrw9b2：{
emailuser：hsjsjsjjsjsj@mdm.mdmdmdmndn，
mobileUser：9999999999，
nameuser：hshs，
passworduser：ppppppl
}，
YJhf16ZyfWUn1Dou3BPcIkSSmVm1：{
emailuser：test2@gmail.com，
mobileUser：1234567892，
nameuser：test2，
passworduser：test2pp
}，
yQEFEe5x06hvSZP18Mmb6OfNqnB2：{
emailuser：test1 @ gmail。 com，
mobileUse r：1234567891，
nameuser：test1，
passworduser：test1pp
}
}
}
UserInformation.class
package com.rishav.t2;
/ **
*由rishav于6/27/2017创建。
* /
public class UserInformation {
private String email;
私人字符串名称;
private String phoneno;
私人字符串密码;
$ b public UserInformation（）{
}
public String getEmail（）{
return email;
}
public void setEmail（String email）{
this.email = email;
}
public String getName（）{
return name;
}
public void setName（String name）{
this.name = name;
}
public String getPhoneno（）{
return phoneno;
public void setPhoneno（String phoneno）{
this.phoneno = phoneno;
}
public String getPassword（）{
return password;
}
public void setPassword（String password）{
this.password = password;
解决方案
Set myRef： myRef = FirebaseDatabase.getInstance（）。getReference（Users）。child（user.getUid（））;
$ p
$ b pre $ private $ show data（dataSnapshot dataSnapshot）{
UserInformation uInfo = ds.getValue（UserInformation.class）;
Log.i（TAG，+ uInfo.getEmail（））; //总是返回null
Log.i（TAG，+ uInfo.getName（））; //总是返回null
Log.i（TAG，+ uInfo.getPassword（））; //总是返回null
Log.i（TAG，+ uInfo.getPhoneno（））; //总是返回null
拥有UserInformation类变量匹配firebase数据库中存在的键名：
public class UserInformation {
public String emailuser;
public String nameuser;
public String mobileUser;
public String passworduser;
$ b public UserInformation（）{
}
public String getEmail（）{
return email;
}
public void setEmail（String email）{
this.email = email;
}
public String getName（）{
return name;
}
public void setName（String name）{
this.name = name;
}
public String getPhoneno（）{
return phoneno;
public void setPhoneno（String phoneno）{
this.phoneno = phoneno;
}
public String getPassword（）{
return password;
}
public void setPassword（String password）{
this.password = password;
}
I have a class to read data from my database but it always returns null.
Here's the java file
public class UserActivity extends AppCompatActivity {
TextView textView;
private FirebaseDatabase mFirebaseDatabase;
private FirebaseAuth mAuth;
private FirebaseAuth.AuthStateListener mAuthListener;
private DatabaseReference myRef;
private String userID;
private String TAG = "hifiwi";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_user);
textView = (TextView) findViewById(R.id.textView);
//////////////////////////////////////////////////////////////
mAuth = FirebaseAuth.getInstance();
mFirebaseDatabase = FirebaseDatabase.getInstance();
myRef = mFirebaseDatabase.getReference();
FirebaseUser user = mAuth.getCurrentUser();
userID = user.getUid();
mAuthListener = new FirebaseAuth.AuthStateListener() {
@Override
public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
FirebaseUser user = mAuth.getCurrentUser();
if (user != null) {
Toast.makeText(UserActivity.this, "Signed in with " + user.getEmail(), Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(UserActivity.this, "Successfully signed out...", Toast.LENGTH_SHORT).show();
}
}
};
myRef.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
showData(dataSnapshot);
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
///////////////////////////////////////////////////////////////
}
private void showData(DataSnapshot dataSnapshot) {
for (DataSnapshot ds : dataSnapshot.getChildren()) {
UserInformation uInfo = new UserInformation();
uInfo.setEmail(ds.child(userID).getValue(UserInformation.class).getEmail());
uInfo.setName(ds.child(userID).getValue(UserInformation.class).getName());
uInfo.setPassword(ds.child(userID).getValue(UserInformation.class).getPassword());
uInfo.setPhoneno(ds.child(userID).getValue(UserInformation.class).getPhoneno());
Log.i(TAG, " " + uInfo.getEmail()); //Always returning null
Log.i(TAG, " " + uInfo.getName()); //Always returning null
Log.i(TAG, " " + uInfo.getPassword()); //Always returning null
Log.i(TAG, " " + uInfo.getPhoneno()); //Always returning null
}
}
@Override
protected void onStart() {
super.onStart();
mAuth.addAuthStateListener(mAuthListener);
}
@Override
protected void onStop() {
super.onStop();
mAuth.removeAuthStateListener(mAuthListener);
}
}
The log statements always return null.
This is my database structure under t2-login(the project name).
{
"Users" : {
"8dQ8unnqQXa69nkxUFKrcgiTM3S2" : {
"emailuser" : "sam@gmail.com",
"mobileUser" : "1234567899",
"nameuser" : "sam",
"passworduser" : "sammypp"
},
"DIMBAk4CHZdWGbxN9kPESwIrw9b2" : {
"emailuser" : "hsjsjsjjsjsj@mdm.mdmdmdmndn",
"mobileUser" : "9999999999",
"nameuser" : "hshs",
"passworduser" : "ppppppl"
},
"YJhf16ZyfWUn1Dou3BPcIkSSmVm1" : {
"emailuser" : "test2@gmail.com",
"mobileUser" : "1234567892",
"nameuser" : "test2",
"passworduser" : "test2pp"
},
"yQEFEe5x06hvSZP18Mmb6OfNqnB2" : {
"emailuser" : "test1@gmail.com",
"mobileUser" : "1234567891",
"nameuser" : "test1",
"passworduser" : "test1pp"
}
}
}
The UserInformation.class
package com.rishav.t2;
/**
* Created by rishav on 6/27/2017.
*/
public class UserInformation {
private String email;
private String name;
private String phoneno;
private String password;
public UserInformation() {
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPhoneno() {
return phoneno;
}
public void setPhoneno(String phoneno) {
this.phoneno = phoneno;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
解决方案
Set myRef to: myRef = FirebaseDatabase.getInstance().getReference("Users").child(user.getUid());
Also change this:
private void showData(DataSnapshot dataSnapshot) {
UserInformation uInfo = ds.getValue(UserInformation.class);
Log.i(TAG, " " + uInfo.getEmail()); //Always returning null
Log.i(TAG, " " + uInfo.getName()); //Always returning null
Log.i(TAG, " " + uInfo.getPassword()); //Always returning null
Log.i(TAG, " " + uInfo.getPhoneno()); //Always returning null
}
Have UserInformation class variables match the key names that exist in the firebase database:
public class UserInformation {
public String emailuser;
public String nameuser;
public String mobileUser;
public String passworduser;
public UserInformation() {
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPhoneno() {
return phoneno;
}
public void setPhoneno(String phoneno) {
this.phoneno = phoneno;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
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