DataSnapshot每次都会获得一个用户信息

Question

我收到FirebaseUser ID＆amp;电子邮件如何正确登录，如调试屏幕截图所示，但DataSnapshot ds总是加载user_01信息，我努力解决这个问题，并在网站上发现类似问题，但无法提供帮助。所以有人可以帮忙解决这个问题吗？

public class AddToDatabase extends AppCompatActivity {
private static final String TAG = "AddToDatabase";
private ListView userInfolist;
private FirebaseAuth mAuth;
private FirebaseAuth.AuthStateListener mAuthListener;
String userId;
UserInformations uInfo = new UserInformations();
DatabaseReference myRef;
FirebaseDatabase mFirebaseDatabase;
FirebaseUser user;

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

    userInfolist = (ListView) findViewById(R.id.userInfolist);
    mAuth = FirebaseAuth.getInstance();
    mFirebaseDatabase = FirebaseDatabase.getInstance();
    myRef = mFirebaseDatabase.getReference();
    user = mAuth.getCurrentUser();
    userId = user.getUid();

    mAuthListener = new FirebaseAuth.AuthStateListener() {
        @Override
        public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
            FirebaseUser user = firebaseAuth.getCurrentUser();
            if (user != null) {                   
                Log.d(TAG, "onAuthStateChanged:signed_in:" + user.getUid());
                toastMassege(" You are successfly signed in with " + user.getEmail());
            } else {                 
                Log.d(TAG, "onAuthStateChanged:signed_out");
                toastMassege(" You are successfly signed out ");
            }
        }
    };        
    myRef.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {              
            showData(dataSnapshot);
        }
        @Override
        public void onCancelled(DatabaseError error) {         
       }
    });
}

Boolean signedstate = true;
private void showData(DataSnapshot dataSnapshot) {
    ArrayList<String> arrayList = new ArrayList<>();

    for (DataSnapshot ds : dataSnapshot.getChildren()) {
        if (signedstate) {        
            uInfo.setName(ds.getValue(UserInformations.class).getName());
            uInfo.setEmail(ds.getValue(UserInformations.class).getEmail());
            uInfo.setPhone_num(ds.getValue(UserInformations.class).getPhone_num());

            arrayList.add(uInfo.getName());
            arrayList.add(uInfo.getEmail());
            arrayList.add(uInfo.getPhone_num());
            ArrayAdapter<String> adapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, arrayList);
            userInfolist.setAdapter(adapter);
            toastMassege("its Done ");
            signedstate = false;
        }
    }
}

@Override
public void onStart() {
    super.onStart();
    mAuth.addAuthStateListener(mAuthListener);
}

@Override
public void onStop() {
    super.onStop();
    if (mAuthListener != null) {
        mAuth.removeAuthStateListener(mAuthListener);
    }
}

private void toastMassege(String massege) {
    Toast.makeText(this, massege, Toast.LENGTH_SHORT).show();
  }

}

这是类UserInformations：

class UserInformations {

public String email,name,phone_num ;

UserInformations() {
}

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 getPhone_num() {
    return phone_num;
}

public void setPhone_num(String phone_num) {
    this.phone_num = phone_num;
}
}

Answer 1

您的问题是您正在for循环中创建适配器。为了解决你的问题，你需要移动这一行：

ArrayAdapter<String> adapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, arrayList);

在for循环之外的

因为每次迭代时都在创建ArrayAdapter的新实例。请使用以下代码：

private void showData(DataSnapshot dataSnapshot) {
    ArrayList<String> arrayList = new ArrayList<>();

    for (DataSnapshot ds : dataSnapshot.getChildren()) {
        if (signedstate) {        
            uInfo.setName(ds.getValue(UserInformations.class).getName());
            uInfo.setEmail(ds.getValue(UserInformations.class).getEmail());
            uInfo.setPhone_num(ds.getValue(UserInformations.class).getPhone_num());

            arrayList.add(uInfo.getName());
            arrayList.add(uInfo.getEmail());
            arrayList.add(uInfo.getPhone_num());
            signedstate = false;
        }
    }
    ArrayAdapter<String> adapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, arrayList);
    userInfolist.setAdapter(adapter);
    toastMassege("its Done ");
}