点击注册按钮APP崩溃，FirebaseApp未初始化问题求助

异常信息 #

IllegalStateException: Default FirebaseApp is not initialized in this process typroject. Make sure to call FirebaseApp.initializeApp(Context) first。

问题场景 #

点击注册按钮时APP崩溃，使用Firebase Auth和Database功能，自行添加的Firebase相关依赖如下：

implementation 'com.google.firebase:firebase-auth:21.1.0'
implementation 'com.google.firebase:firebase-database:20.1.0'
implementation 'com.google.firebase:firebase-firestore:24.4.2'
implementation 'com.google.firebase:firebase-storage:20.1.0'

RegisterActivity代码：

package com.example.typroject;

public class registerActivity extends AppCompatActivity {
    private DatabaseReference mRootref;
    private FirebaseAuth mAuth;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_register);
        mRootref = FirebaseDatabase.getInstance().getReference();
        mAuth = FirebaseAuth.getInstance();
        register.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String txtUsername = username.getText().toString();
                String txtName = name.getText().toString();
                String txtemail = email.getText().toString();
                String txtpassword = password.getText().toString();

                if(TextUtils.isEmpty(txtUsername) || TextUtils.isEmpty(txtName) || TextUtils.isEmpty(txtemail) || TextUtils.isEmpty(txtpassword)){
                    Toast.makeText(registerActivity.this, "Empty Credentials", Toast.LENGTH_SHORT).show();
                } else if (txtpassword.length() < 6) {
                    Toast.makeText(registerActivity.this, "Password is too Short", Toast.LENGTH_SHORT).show();
                }else {
                    registeruser(txtUsername, txtName , txtemail , txtpassword );
//                    startActivity(new Intent(registerActivity.this , MainActivity.class).addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK | Intent.FLAG_ACTIVITY_CLEAR_TOP));
                }

            }


        });
    }


    private void registeruser(String Username, String Name, String email, String password) {
        mAuth.createUserWithEmailAndPassword(email, password).addOnSuccessListener(new OnSuccessListener<AuthResult>() {
            @Override
            public void onSuccess(AuthResult authResult) {
                HashMap<String , Object> map = new HashMap<>();
                map.put("username" , username);
                map.put("name" , name);
                map.put("email" , email);
                map.put("password" , password);
                map.put("id" , mAuth.getCurrentUser().getUid());

                mRootref.child("Users").child(mAuth.getCurrentUser().getUid()).setValue(map).addOnCompleteListener(new OnCompleteListener<Void>() {
                    @Override
                    public void onComplete(@NonNull Task<Void> task) {
                        Intent intent = new Intent(registerActivity.this , MainActivity.class);
                        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK | Intent.FLAG_ACTIVITY_CLEAR_TOP);
                        startActivity(intent);
                        finish();
                    }
                });
            }
        }).addOnFailureListener(new OnFailureListener() {
            @Override
            public void onFailure(@NonNull Exception e) {
                Toast.makeText(registerActivity.this, e.getMessage(), Toast.LENGTH_SHORT).show();
            }
        });
    }
}

解决方案 #

1. 补充Firebase配置文件与插件 #

• 从Firebase控制台下载google-services.json文件，放置到app模块根目录（与app/build.gradle同级）。
• 确认项目级build.gradle中添加Google Services插件依赖：

  buildscript {
      dependencies {
          classpath 'com.google.gms:google-services:4.4.0' // 或最新兼容版本
      }
  }
  

• 在app级build.gradle末尾添加插件应用代码：

  apply plugin: 'com.google.gms.google-services'
  

2. 统一Firebase依赖版本 #

不同Firebase组件版本不一致会引发初始化异常，推荐用Firebase BOM统一管理版本：

// 在app级build.gradle中添加BOM依赖
implementation platform('com.google.firebase:firebase-bom:32.7.0') // 使用最新稳定版本

// 移除各组件的版本号，由BOM统一管理
implementation 'com.google.firebase:firebase-auth'
implementation 'com.google.firebase:firebase-database'
implementation 'com.google.firebase:firebase-firestore'
implementation 'com.google.firebase:firebase-storage'

3. 可选：手动初始化Firebase #

若自动初始化失败，可自定义Application类手动初始化：

1. 创建自定义Application类：

package com.example.typroject;

import android.app.Application;
import com.google.firebase.FirebaseApp;

public class MyApplication extends Application {
    @Override
    public void onCreate() {
        super.onCreate();
        FirebaseApp.initializeApp(this);
    }
}

2. 在AndroidManifest.xml中指定该Application：

<application
    android:name=".MyApplication"
    ...>
    ...
</application>

4. 修复代码中的其他潜在问题 #

• View未初始化：register、username等View需在onCreate中用findViewById绑定，否则会抛出NullPointerException：

  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_register);
      // 绑定View（替换为你的实际控件ID）
      Button register = findViewById(R.id.register_btn);
      EditText username = findViewById(R.id.username_et);
      EditText name = findViewById(R.id.name_et);
      EditText email = findViewById(R.id.email_et);
      EditText password = findViewById(R.id.password_et);
  
      mRootref = FirebaseDatabase.getInstance().getReference();
      mAuth = FirebaseAuth.getInstance();
      // 后续代码...
  }
  

• 数据存储错误：registeruser方法中，map存储的是View对象而非用户输入文本，应改为传入的参数：

  map.put("username", Username); // 替换原代码中的username（View对象）
  map.put("name", Name); // 替换原代码中的name（View对象）
  

• 类名规范：registerActivity应改为RegisterActivity，符合Java大驼峰命名规范。

内容的提问来源于stack exchange，提问作者Rushikesh Vadnal