Question

我正在开发我的第一个firebase android应用程序，它几乎已经完成，但我仍然坚持从数据库中检索数据，添加和更新数据工作正常。在我的viewInformation布局中，它没有进入showData方法的forloop（使用log cat检查）我想将数据显示给登录的特定用户。（仅显示他/她的数据）

这是我的Firebase数据库结构：

显示信息代码：

public class ViewInformation extends AppCompatActivity {

private static final String TAG = "ViewInformation";
private FirebaseDatabase mFirebaseDatabase;
private FirebaseAuth auth;
private FirebaseAuth.AuthStateListener authListener;
private DatabaseReference mRef;
String userID;
private ListView mListView;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_view_information);
    Toast.makeText(getApplicationContext(), "Showing Details...", Toast.LENGTH_SHORT).show();
    mListView = findViewById(R.id.listview);

    auth = FirebaseAuth.getInstance();
    mFirebaseDatabase = FirebaseDatabase.getInstance();
    mRef = mFirebaseDatabase.getReference();
    final FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser(); //get current user
    userID = user.getUid(); //get userID of current user

    authListener = new FirebaseAuth.AuthStateListener() {
        @Override
        public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
            FirebaseUser user = firebaseAuth.getCurrentUser();
            if (user == null) {
                // user auth state is changed - user is null ...launch login activity
                startActivity(new Intent(ViewInformation.this, LoginActivity.class));
                finish();
            }
        }
    };


      mRef.addValueEventListener(new ValueEventListener() {
          @Override
          public void onDataChange(DataSnapshot dataSnapshot) {
              Toast.makeText(getApplicationContext(), "Showing Details...", Toast.LENGTH_SHORT).show();
              showData(dataSnapshot);
          }

          @Override
          public void onCancelled(DatabaseError databaseError) {
          }

      });
}

private void showData(DataSnapshot dataSnapshot) {
    Toast.makeText(getApplicationContext(), "...", Toast.LENGTH_SHORT).show();
    for(DataSnapshot ds:dataSnapshot.getChildren()){

        userInformation uInfo = new userInformation();
        uInfo.setName(ds.child(userID).child("Name").getValue(userInformation.class).getName());
        uInfo.setGender(ds.child(userID).child("Gender").getValue(userInformation.class).getGender());
        uInfo.setMobile_Number(ds.child(userID).child("Mobile_Number").getValue(userInformation.class).getMobile_Number());
        uInfo.setAddress(ds.child(userID).child("Address").getValue(userInformation.class).getAddress());

        Log.d(TAG, "showData: Name: " + uInfo.getName());
        Log.d(TAG, "showData: Gender: " + uInfo.getGender());
        Log.d(TAG, "showData: Mobile_Number: " + uInfo.getMobile_Number());
        Log.d(TAG, "showData: Address: " + uInfo.getAddress());

        ArrayList<String> array = new ArrayList<>();
        array.add(uInfo.getName());
        array.add(uInfo.getGender());
        array.add(uInfo.getMobile_Number());
        array.add(uInfo.getAddress());
        ArrayAdapter adapter = new ArrayAdapter(this, android.R.layout.simple_list_item_1,array);
        mListView.setAdapter(adapter);
    }
}


@Override
public void onStart() {
    super.onStart();
    auth.addAuthStateListener(authListener);
}

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

Getter / Setter方法：（userInformation.java）

package com.scoratech.scoraxchange;
public class userInformation {

private String Name;
private String Gender;
private String Mobile_Number;
private String Address;

 public userInformation(){
 }

public String getName() {
    return Name;
}

public void setName(String name) {
    this.Name = name;
}

public String getGender() {
    return Gender;
}

public void setGender(String gender) {
    this.Gender = gender;
}

public String getMobile_Number() {
    return Mobile_Number;
}

public void setMobile_Number(String mobile_Number) {
    this.Mobile_Number = mobile_Number;
}

public String getAddress() {
    return Address;
}

public void setAddress(String address) {
    this.Address = address;
}
}

Answer 1

您正在mFirebaseDatabase.getReference("list-abc05")中检索不存在的节点。项目数据库的根目录未命名，因此：

mRef = mFirebaseDatabase.getReference();

此外，我建议仅在用户通过身份验证后附加侦听器（因此从onAuthStateChanged内部）。这样你就已经知道了用户的UID，因此可以直接连接到他们的节点（而不是为所有用户检索数据）：

final FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();     
authListener = new FirebaseAuth.AuthStateListener() {
    @Override
    public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
        FirebaseUser user = firebaseAuth.getCurrentUser();
        if (user == null) {
            startActivity(new Intent(ViewInformation.this, LoginActivity.class));
            finish();
        }
        else {
            userID = user.getUid();
            mRef.child(userID).addValueEventListener(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    Toast.makeText(getApplicationContext(), "Showing Details...", Toast.LENGTH_SHORT).show();
                    showData(dataSnapshot);
                }

                @Override
                public void onCancelled(DatabaseError databaseError) {
                    throw databaseError.toException(); // never ignore errors
                }
            });
        }
    }
};

private void showData(DataSnapshot ds) {

    userInformation uInfo = new userInformation();
    uInfo.setName(ds.child(userID).child("Name").getValue(userInformation.class).getName());
    uInfo.setGender(ds.child(userID).child("Gender").getValue(userInformation.class).getGender());
    uInfo.setMobile_Number(ds.child(userID).child("Mobile_Number").getValue(userInformation.class).getMobile_Number());
    uInfo.setAddress(ds.child(userID).child("Address").getValue(userInformation.class).getAddress());

    Log.d(TAG, "showData: Name: " + uInfo.getName());
    Log.d(TAG, "showData: Gender: " + uInfo.getGender());
    Log.d(TAG, "showData: Mobile_Number: " + uInfo.getMobile_Number());
    Log.d(TAG, "showData: Address: " + uInfo.getAddress());

    ArrayList<String> array = new ArrayList<>();
    array.add(uInfo.getName());
    array.add(uInfo.getGender());
    array.add(uInfo.getMobile_Number());
    array.add(uInfo.getAddress());
    ArrayAdapter adapter = new ArrayAdapter(this, android.R.layout.simple_list_item_1,array);
    mListView.setAdapter(adapter);
}

如何在Firebase中将特定用户数据显示到ListView中？

1 个答案: