从 Firebase 实时数据库中删除用户数据

Question

我仍在开发我的登录应用程序。目前，用户可以注册、登录和更新个人资料信息。数据存储在 firebase 实时数据库中，并且 athentificacion 也通过 firebase 工作。我想添加一个“删除配置文件”按钮，以便从 firebase 中删除用户信息。我想出了如何从认证过程中删除用户。现在我尝试向 Uid 调用 remove() 函数，所以现在数据在实时数据库中被删除，但仍在 Firebase 身份验证中，如果删除用户数据，应用程序将崩溃。因此，只有一个删除过程有效……验证或从数据库中删除用户。 也许问题在于实时数据库中的结构和子/父关系？我的建议是 onClickListener() 中的顺序可能不正确？ 我怎样才能一次删除它并让这个过程正常工作？ 提前谢谢:)

public class UpdateProfilActivity extends AppCompatActivity {

private EditText newUserVorname, newUserNachname,newUserStrasse,newUserHnr,newUserPlz,newUserStadt,newUserLand;
private Button speichern;
private FirebaseAuth firebaseAuth;
private FirebaseDatabase firebaseDatabase;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_update_profil);

    newUserVorname=findViewById(R.id.editTextVornameUpdate);
    newUserNachname=findViewById(R.id.editTextNachnameUpdate);
    newUserStrasse=findViewById(R.id.editTextStrasse);
    newUserHnr=findViewById(R.id.editTextHNr);
    newUserPlz=findViewById(R.id.editTextPlz);
    newUserStadt=findViewById(R.id.editTextStadt);
    newUserLand=findViewById(R.id.editTextLand);
    speichern=findViewById(R.id.buttonSpeichern);

    getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    getSupportActionBar().setDisplayShowTitleEnabled(false);

    firebaseAuth= FirebaseAuth.getInstance();
    firebaseDatabase= FirebaseDatabase.getInstance();

    final DatabaseReference databaseReference= firebaseDatabase.getReference(firebaseAuth.getUid());

    databaseReference.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            UserProfil userProfil=dataSnapshot.getValue(UserProfil.class);
            newUserVorname.setText(userProfil.getVorname());
            newUserNachname.setText(userProfil.getNachname());
            newUserStrasse.setText(userProfil.getStrasse());
            newUserHnr.setText(userProfil.getHnr());
            newUserPlz.setText(userProfil.getPlz());
            newUserStadt.setText(userProfil.getStadt());
            newUserLand.setText(userProfil.getLand());
        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {
            Toast.makeText(UpdateProfilActivity.this,"Database Error",Toast.LENGTH_SHORT).show();
        }
    });

    speichern.setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick(View view){
            String Vorname = newUserVorname.getText().toString();
            String Nachname = newUserNachname.getText().toString();
            String Strasse = newUserStrasse.getText().toString();
            String HNr = newUserHnr.getText().toString();
            String Plz = newUserPlz.getText().toString();
            String Stadt = newUserStadt.getText().toString();
            String Land = newUserLand.getText().toString();


            UserProfil userProfil=new UserProfil(Vorname,Nachname,Strasse,HNr,Plz,Stadt,Land);

            databaseReference.setValue(userProfil);

            finish();

        }

    });

}
@Override
public boolean onOptionsItemSelected(@NonNull MenuItem item) {
    switch(item.getItemId()){
        case android.R.id.home:
            onBackPressed();
    }
    return super.onOptionsItemSelected(item);
}

用户配置文件

public class UserProfil {
public String vorname;
public String nachname;
public String strasse;
public String hnr;
public String plz;
public String stadt;
public String land;

public UserProfil(){

}


public UserProfil(String Vorname, String Nachname,String Strasse,String HNr,String Plz,String Stadt,String Land) {
    this.vorname = Vorname;
    this.nachname = Nachname;
    this.strasse= Strasse;
    this.hnr= HNr;
    this.plz=Plz;
    this.stadt=Stadt;
    this.land=Land;

}

public String getVorname() {
   return vorname;
}

public void setVorname(String vorname) {
    this.vorname = vorname;
}

public String getNachname() {
    return nachname;
}

public void setNachname(String nachname) {
    this.nachname = nachname;
}

public void setStrasse(String strasse) {
    this.strasse = strasse;
}

public String getStrasse() {
    return strasse;
}

public void setHnr(String hnr) {
    this.hnr = hnr;
}

public String getHnr() {
    return hnr;
}

public void setPlz(String plz) {
    this.plz = plz;
}

public String getPlz() {
    return plz;
}

public void setStadt(String stadt) {
    this.stadt = stadt;
}

public String getStadt() {
    return stadt;
}

public void setLand(String land) {
    this.land = land;
}

public String getLand() {
    return land;
}

这里是崩溃的logcat

Process: com.example.login, PID: 29022
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.login/com.example.login.ProfileActivity}: java.lang.NullPointerException: Can't pass null for argument 'pathString' in FirebaseDatabase.getReference()
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2464)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2524)
    at android.app.ActivityThread.access$900(ActivityThread.java:154)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1391)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:234)
    at android.app.ActivityThread.main(ActivityThread.java:5526)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
 Caused by: java.lang.NullPointerException: Can't pass null for argument 'pathString' in FirebaseDatabase.getReference()
    at com.google.firebase.database.FirebaseDatabase.getReference(com.google.firebase:firebase-database@@19.0.0:164)
    at com.example.login.ProfileActivity.onCreate(ProfileActivity.java:49)
    at android.app.Activity.performCreate(Activity.java:6285)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1108)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2417)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2524) 
    at android.app.ActivityThread.access$900(ActivityThread.java:154) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1391) 
    at android.os.Handler.dispatchMessage(Handler.java:102) 
    at android.os.Looper.loop(Looper.java:234) 
    at android.app.ActivityThread.main(ActivityThread.java:5526) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 

编辑：

问题出现在以下行： DatabaseReference databaseReference= firebaseDatabase.getReference(firebaseAuth.getUid());

public class ProfileActivity extends AppCompatActivity {

private TextView profilVorname,profilNachname,profilStrasse,profilHNr,profilPlz,profilStadt,profilLand;
private Button profilUpdate,PasswortUpdate;
private FirebaseAuth firebaseAuth;
private FirebaseDatabase firebaseDatabase;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_profile);

    profilVorname= findViewById(R.id.textViewPVorname);
    profilNachname=findViewById(R.id.textViewPNachname);
    profilUpdate=findViewById(R.id.buttonProfilUpdate);
    profilStrasse=findViewById(R.id.textViewPStrasse);
    profilHNr=findViewById(R.id.textViewPHNr);
    profilPlz=findViewById(R.id.textViewPPlz);
    profilStadt=findViewById(R.id.textViewPStadt);
    profilLand=findViewById(R.id.textViewPLand);
    PasswortUpdate=findViewById(R.id.buttonPasswordUpdate);

    getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    getSupportActionBar().setDisplayShowTitleEnabled(false);

    firebaseAuth=FirebaseAuth.getInstance();
    firebaseDatabase= FirebaseDatabase.getInstance();

    DatabaseReference databaseReference= firebaseDatabase.getReference(firebaseAuth.getUid());

    databaseReference.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            UserProfil userProfil=dataSnapshot.getValue(UserProfil.class);
            profilVorname.setText(userProfil.getVorname());
            profilNachname.setText(userProfil.getNachname());
            profilStrasse.setText(userProfil.getStrasse());
            profilHNr.setText(userProfil.getHnr());
            profilPlz.setText(userProfil.getPlz());
            profilStadt.setText(userProfil.getStadt());
            profilLand.setText(userProfil.getLand());

        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {
                Toast.makeText(ProfileActivity.this,"Database Error",Toast.LENGTH_SHORT).show();
        }
    });



    profilUpdate.setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick(View view){
            startActivity(new Intent(ProfileActivity.this,UpdateProfilActivity.class));

        }
    });

    PasswortUpdate.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            startActivity(new Intent(ProfileActivity.this,UpdatePasswortActivity.class));
        }
    });
}

@Override
public boolean onOptionsItemSelected(@NonNull MenuItem item) {
    switch(item.getItemId()){
        case android.R.id.home:
            onBackPressed();
    }
    return super.onOptionsItemSelected(item);
}

@Override
public void onBackPressed() {
    super.onBackPressed();
    startActivity(new Intent(ProfileActivity.this, NavActivity.class));
}

Answer 1

您收到以下错误：

原因：java.lang.NullPointerException: Can't pass null for argument 'pathString' in FirebaseDatabase.getReference()

因为您在以下代码行中向getReference() 方法传递了一个值为null 的对象：

DatabaseReference databaseReference= firebaseDatabase.getReference(firebaseAuth.getUid());

所以firebaseAuth.getUid() 返回null，因为firebaseAuth 对象是null，这意味着您的用户未经过身份验证。

要解决此问题，首先要确保您的用户已通过身份验证。其次，要真正获得uid，您需要在FirebaseUser 对象上调用getUid()，在FirebaseAuth 对象上调用not。所以请把上面这行代码改成：

String uid = firebaseAuth.getCurrentUser().getUid();
//                           ^     ^
DatabaseReference databaseReference= firebaseDatabase.getReference(uid);