在onPause()上删除用于身份验证的Firebase AuthStateListener并将其添加回onResume()的目的

private FirebaseAuth mAuth;
private FirebaseAuth.AuthStateListener mAuthListener;

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

    mAuth = FirebaseAuth.getInstance();

    // 设置认证状态监听器
    mAuthListener = new FirebaseAuth.AuthStateListener() {
        @Override
        public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
            FirebaseUser user = firebaseAuth.getCurrentUser();
            if (user != null) {
                // 用户已登录
            } else {
                // 用户未登录
            }
        }
    };
}

@Override
protected void onStart() {
    super.onStart();
    // 开始监听认证状态
    mAuth.addAuthStateListener(mAuthListener);
}

@Override
protected void onPause() {
    super.onPause();
    // 移除监听器以节省资源
    if (mAuthListener != null) {
        mAuth.removeAuthStateListener(mAuthListener);
    }
}

@Override
protected void onResume() {
    super.onResume();
    // 恢复监听器
    if (mAuthListener != null) {
        mAuth.addAuthStateListener(mAuthListener);
    }
}