Android注册跳转LoginActivity失败及重复注册问题求助

问题详情 #

点击CreateAccount按钮后，预期跳转到LoginActivity，但实际表现：

• 首次点击无任何UI反馈，但Firebase数据库中已完成用户注册
• 再次点击按钮，弹出Toast提示「该邮箱已存在用户」

相关代码与配置 #

1. RegisterActivity 代码 #

import android.content.Intent;
import android.os.Bundle;
import android.text.TextUtils;
import android.util.Log;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;

import java.util.HashMap;
import java.util.Objects;

public class RegisterActivity extends AppCompatActivity {
    private EditText FullName, UserName, EmailAdress, Password,ConfirmPassword;
    private DatabaseReference Mrootref;
    private FirebaseAuth Mauth;


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

        FullName=findViewById(R.id.FullName);
        UserName=findViewById(R.id.UserName);
        EmailAdress=findViewById(R.id.EmailAddress);
        Password=findViewById(R.id.Password);
        ConfirmPassword=findViewById(R.id.ConfirmPassword);
        Button createAccount = findViewById(R.id.CreateAccount);
        TextView logtxt = findViewById(R.id.blogin);

//        Database Reference
        Mrootref=FirebaseDatabase.getInstance().getReference();
        Mauth=FirebaseAuth.getInstance();



        createAccount.setOnClickListener(view -> {
            String txtFullName=FullName.getText().toString();
            String txtUserName=UserName.getText().toString();
            String txtEmailAdress=EmailAdress.getText().toString();
            String txtPassword=Password.getText().toString();
            String txtConfirmPassword=ConfirmPassword.getText().toString();
            if(TextUtils.isEmpty(txtFullName)||TextUtils.isEmpty(txtUserName)||TextUtils.isEmpty(txtEmailAdress)||TextUtils.isEmpty(txtPassword)||TextUtils.isEmpty(txtConfirmPassword)) {
                Toast.makeText(RegisterActivity.this, "You have missed something", Toast.LENGTH_SHORT).show();
            }else if (txtPassword.length() <= 7) {
                    Toast.makeText(RegisterActivity.this, "The Password must have atleast 8 character", Toast.LENGTH_SHORT).show();
                }else if(!txtPassword.equals(txtConfirmPassword)) {
                    Toast.makeText(RegisterActivity.this, "The Password You Entered is not same check it again", Toast.LENGTH_SHORT).show();
                }else{
                registerUser(txtFullName, txtUserName, txtEmailAdress, txtPassword);
            }
        });



        logtxt.setOnClickListener(view -> startActivity(new Intent(RegisterActivity.this,LoginActivity.class)));

//        Removeable Lines
        TextView skip = findViewById(R.id.skip);
        skip.setOnClickListener(view -> {
            Intent hmActivity = new Intent(RegisterActivity.this, MainActivity.class);
            startActivity(hmActivity);
        });
    }
    public void registerUser(final String FullName, final String UserName, final String EmailAdress, final String Password){
        Mauth.createUserWithEmailAndPassword(EmailAdress, Password).addOnSuccessListener(authResult -> {
            HashMap<String, Object> map=new HashMap<>();
            map.put("fullname", FullName);
            map.put("username", UserName);
            map.put("emailadress", EmailAdress);
            map.put("id", Objects.requireNonNull(Mauth.getCurrentUser()).getUid());

            Mrootref.child("Users").child(Mauth.getCurrentUser().getUid()).setValue(map).addOnCompleteListener(task -> {
                if (task.isSuccessful()){
                    Intent intent=new Intent(RegisterActivity.this, LoginActivity.class).addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK|Intent.FLAG_ACTIVITY_CLEAR_TOP);
                    Log.d("RegisterActivity", "User registration completed");
                    Toast.makeText(RegisterActivity.this, "Welcome to DreamOway!", Toast.LENGTH_SHORT).show();
                    Log.d("RegisterActivity", "Starting MainActivity"); // 此处Log笔误，实际跳转LoginActivity
                    startActivity(intent);
                    finish();
                }
                // 未处理数据库写入失败的情况
            });
        }).addOnFailureListener(e -> {
            Log.d("RegisterActivity", "Error in database operation: " + e.getMessage());
            // 未向用户展示Auth失败的Toast提示
        });
    }
}

2. App级build.gradle 配置 #

plugins {
     id 'com.android.application' id 'com.google.gms.google-services'
}

android {
    namespace 'com.example.dreamoway' compileSdk 33
    defaultConfig {
    applicationId "com.example.dreamoway"
    minSdk 26
    targetSdk 33
    versionCode 1
    versionName "1.0"
    testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
    }
}
compileOptions {
    sourceCompatibility JavaVersion.VERSION_1_8
    targetCompatibility JavaVersion.VERSION_1_8
}
}

dependencies {
implementation 'androidx.appcompat:appcompat:1.6.1'
implementation 'com.google.android.material:material:1.8.0'
implementation 'androidx.constraintlayout:constraintlayout:2.1.4'
implementation 'de.hdodenhof:circleimageview:3.1.0'
implementation 'com.google.firebase:firebase-database:20.1.0'
implementation 'com.google.firebase:firebase-auth:21.2.0'
implementation 'com.google.firebase:firebase-bom:31.4.0'
testImplementation 'junit:junit:4.13.2'
androidTestImplementation 'androidx.test.ext:junit:1.1.5'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.5.1'
}

3. 项目级build.gradle 配置 #

buildscript { dependencies {
    classpath 'com.google.gms:google-services:4.3.15'

}
} plugins { id 'com.android.application' version '7.4.2' apply false id 'com.android.library' version '7.4.2' apply false id 'com.google.android.libraries.mapsplatform.secrets-gradle-plugin' version '2.0.1' apply false }

问题原因分析 #

1. 数据库写入失败无反馈：仅当Realtime Database写入成功时才会跳转并显示Toast，若写入失败（如权限配置错误、网络波动），代码未做任何UI提示，导致用户以为首次点击无反应，但此时Firebase Auth已成功创建用户。
2. Auth失败无用户提示：addOnFailureListener仅打印日志，未向用户展示错误Toast，再次点击时Auth检测到邮箱已存在，用户看到的Toast可能来自Firebase内部逻辑。
3. Log笔误：代码中打印的Starting MainActivity与实际跳转的LoginActivity不符，易造成调试混淆。

修复方案 #

1. 完善错误反馈逻辑 #

修改registerUser方法，添加数据库写入失败的提示，同时在Auth失败时向用户展示错误信息：

public void registerUser(final String FullName, final String UserName, final String EmailAdress, final String Password){
    Mauth.createUserWithEmailAndPassword(EmailAdress, Password).addOnSuccessListener(authResult -> {
        HashMap<String, Object> map=new HashMap<>();
        map.put("fullname", FullName);
        map.put("username", UserName);
        map.put("emailadress", EmailAdress);
        map.put("id", Objects.requireNonNull(Mauth.getCurrentUser()).getUid());

        Mrootref.child("Users").child(Mauth.getCurrentUser().getUid()).setValue(map).addOnCompleteListener(task -> {
            if (task.isSuccessful()){
                Intent intent=new Intent(RegisterActivity.this, LoginActivity.class).addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK|Intent.FLAG_ACTIVITY_CLEAR_TOP);
                Log.d("RegisterActivity", "User registration completed");
                Toast.makeText(RegisterActivity.this, "Welcome to DreamOway!", Toast.LENGTH_SHORT).show();
                Log.d("RegisterActivity", "Starting LoginActivity"); // 修正Log笔误
                startActivity(intent);
                finish();
            } else {
                // 数据库写入失败提示
                Toast.makeText(RegisterActivity.this, "Failed to save user info: " + Objects.requireNonNull(task.getException()).getMessage(), Toast.LENGTH_SHORT).show();
                // 可选：删除已创建的Auth用户，避免脏数据
                Mauth.getCurrentUser().delete();
            }
        });
    }).addOnFailureListener(e -> {
        Log.d("RegisterActivity", "Auth error: " + e.getMessage());
        // 向用户展示Auth失败原因
        Toast.makeText(RegisterActivity.this, "Registration failed: " + e.getMessage(), Toast.LENGTH_SHORT).show();
    });
}

2. 检查Firebase Realtime Database权限 #

确保数据库规则允许认证用户写入数据，开发环境可使用以下规则（生产环境需细化权限）：

{
  "rules": {
    ".read": "auth != null",
    ".write": "auth != null"
  }
}

3. 修正Log信息 #

将Log.d("RegisterActivity", "Starting MainActivity");改为Log.d("RegisterActivity", "Starting LoginActivity");，保持日志与实际行为一致。

内容的提问来源于stack exchange，提问作者Hussain Mohiuddin