Question

所以我试图从我的firebase数据库中检索用户个人资料信息，以便在我的Android应用程序上显示它，但它似乎根本不起作用！

这是我尝试过的代码，但根本没有运气！

package com.example.ravneet.bloodhub;

import android.content.Intent; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.util.Log; import android.view.View; import android.widget.EditText; import android.widget.TextView;

import com.google.firebase.auth.FirebaseAuth; import com.google.firebase.auth.FirebaseUser; import com.google.firebase.database.ChildEventListener; import com.google.firebase.database.DataSnapshot; import com.google.firebase.database.DatabaseError; import com.google.firebase.database.DatabaseReference; import com.google.firebase.database.FirebaseDatabase;

import java.util.ArrayList;

public class Editprofile extends AppCompatActivity {
    TextView chngpsw;
    EditText name, state, city, bloodgrp, mobileno, email;
    FirebaseUser currentFirebaseUser;
    String id;
    private static final String TAG = "EditProfile";
    ArrayList<String> mylist;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_editprofile);
        mylist  = new ArrayList<String>();
        chngpsw = (TextView) findViewById(R.id.chngpsw);
        currentFirebaseUser = FirebaseAuth.getInstance().getCurrentUser();
        id = currentFirebaseUser.getUid();
        setTitle("Edit Profile");
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        name = (EditText) findViewById(R.id.name);
        state = (EditText) findViewById(R.id.state);
        city = (EditText) findViewById(R.id.city);
        bloodgrp = (EditText) findViewById(R.id.bloodgrp);
        mobileno = (EditText) findViewById(R.id.mobileno);
        email = (EditText) findViewById(R.id.email);
        chngpsw.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent i = new Intent(getApplicationContext(), Changepswrd.class);
                startActivity(i);
            }
        });
        readData();
        if(mylist.size() != 0){
            setvalues();
        }
        //Log.d(TAG, "SIZE IS on Create " + mylist.size());
    }

    private void readData() {

        DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("Users").child(id);
       // Log.d(TAG, "UserID is " + id);
        ref.addChildEventListener(new ChildEventListener() {
            @Override
            public void onChildAdded(DataSnapshot dataSnapshot, String s) {
               fetchdata(dataSnapshot);

            }

            @Override
            public void onChildChanged(DataSnapshot dataSnapshot, String s) {
                fetchdata(dataSnapshot);
            }

            @Override
            public void onChildRemoved(DataSnapshot dataSnapshot) {

            }

            @Override
            public void onChildMoved(DataSnapshot dataSnapshot, String s) {

            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });
        Log.d(TAG, "Bottom Size :   " + mylist.size());

    }
    private void fetchdata(DataSnapshot dataSnapshot){
        String value = dataSnapshot.getValue(String.class);
        //Log.d(TAG, "Value is " + value);
        mylist.add(value);
        Log.d(TAG, "Size :   " + mylist.size());
    }
    private void setvalues(){
        bloodgrp.setText(mylist.get(0));
        city.setText(mylist.get(1));
        email.setText(mylist.get(2));
        mobileno.setText(mylist.get(3));
        name.setText(mylist.get(4));
        state.setText(mylist.get(5));
    } }

当我尝试在oncreate方法中打印一个arraylist大小时，它显示0 这是它在logcat中显示的内容

> D/EditProfile: UserID is MkfeHsMuJyaNr5Be8R7eRojHngE2 09-24
> D/EditProfile: Bottom Size :   0 
> D/EditProfile: Size :   1
> D/EditProfile: Size :   2 
> D/EditProfile: Size :   3
> D/EditProfile: Size :   4 
> D/EditProfile: Size :   5
> D/EditProfile: Size :   6

以下是Firebase数据库

Answer 1

您似乎误解了Firebase是异步的。

你需要移动这些线。

setvalues(); 

Log.d(TAG, "Bottom Size :   " + mylist.size());

在这里。

 ref.addChildEventListener(new ChildEventListener() {
        @Override
        public void onChildAdded(DataSnapshot dataSnapshot, String s) {
           fetchdata(dataSnapshot);
           Log.d(TAG, "Bottom Size :   " + mylist.size());
           setvalues();
        }

        @Override
        public void onChildChanged(DataSnapshot dataSnapshot, String s) {
            fetchdata(dataSnapshot);
            Log.d(TAG, "Bottom Size :   " + mylist.size()); 
            setvalues();
        }

但是，您的数据中的快照似乎过于“向下”了fetchdata()。您希望将整个Snapshot作为一个用户获取，而不是将每个String添加到List中。

我建议您使用POJO代替列表来存储用户类数据

例如，如果您想要所有用户，则可以在Users键设置引用，然后DataSnapshot是每个用户值，而不是其中的数据。

final FirebaseDatabase database = FirebaseDatabase.getInstance();

// Here not just getting one ID
DatabaseReference ref = database.getReference().child("Users");

// Attach a listener to read the data at the Users reference
ref.addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        User user = dataSnapshot.getValue(User.class);
        // userList.add(user);  // for example
    }

使用database.getReference().child("Users").child(id);也可能适用于此模式。

从Firebase检索值并在EditText中显示

1 个答案: