无论哪个用户登录，arrayList 总是加载来自 Firebase 数据库的用户信息? [英] arrayList always loaded with user info from Firebase database regardless of which user is signed in?

问题描述

在 showdata 方法中，当我运行应用程序并使用任何用户登录时加载 FirebaseUser 信息，方法中的 arrayList 始终加载 User_03 信息，

In showdata method witch load FirebaseUser info when I run the app and signed in with any user , arrayList in the method is always loaded with User_03 info ,

调试显示:

• DataSnapshot ds 加载了登录用户的正确值(右键和信息).
• uInfo(携带登录用户信息的对象)加载了数据库中的正确数据.
• uInfo.setName(ds.getValue(UserInformations.class).getName());= 未定义.
• 我认为 arryList 的大小有问题.

我在到达断点时截取的附加屏幕截图: toastMassege("it's Done") .

the attached screen shot I take it when arrive to breakpoint in line : toastMassege("it's Done") .

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();
@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();
    FirebaseDatabase mFirebaseDatabase = FirebaseDatabase.getInstance();
    DatabaseReference myRef = mFirebaseDatabase.getReference();
    FirebaseUser 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) {
        }
    });
}
private void showData(DataSnapshot dataSnapshot) {
  for(DataSnapshot ds : dataSnapshot.getChildren()){

      uInfo.setName(ds.getValue(UserInformations.class).getName());
      uInfo.setEmail(ds.getValue(UserInformations.class).getEmail()); 
     uInfo.setPhone_num(ds.getValue(UserInformations.class).getPhone_num());

      ArrayList<String> arrayList=new ArrayList<>();
      int listSize = arrayList.size();
      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 ");
  }
}
@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();
}

 }

这是用户信息类

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;
}
}

推荐答案

发生这种情况是因为您已经声明了 ArrayListarrayList=new ArrayList<>(); 在 for 循环内.这意味着您每次迭代时都在创建 ArrayList 类的新实例.

This is happening because you are have declared the ArrayList<String> arrayList=new ArrayList<>(); inside the for loop. This means that you are creating a new instance of ArrayList class every time you iterate.

为了解决这个问题，只需像这样将decration移到for循环之外:

In order to solve this, just move the decration outside for loop like this:

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

  for(DataSnapshot ds : dataSnapshot.getChildren()){

      uInfo.setName(ds.getValue(UserInformations.class).getName());
      uInfo.setEmail(ds.getValue(UserInformations.class).getEmail()); 
      uInfo.setPhone_num(ds.getValue(UserInformations.class).getPhone_num());

      int listSize = arrayList.size();
      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 ");
  }
}

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