有人可以帮助..listview没有显示项目列表 [英] Can someone please help ..listview is not displaying list of items

问题描述

package com.example.meghana.uftm;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.ListView;

import com.google.firebase.auth.FirebaseAuth;
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 com.google.firebase.database.ValueEventListener;

import java.util.ArrayList;
import java.util.List;

public class FireBase1 extends AppCompatActivity {
    private FirebaseAuth mAuth;
    private DatabaseReference mDatabase;
    List<user> users;
    ListView lv;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_fire_base1);
        lv=(ListView)findViewById(R.id.flistview);
         users=new ArrayList<>();
        mAuth = FirebaseAuth.getInstance();
        mDatabase = FirebaseDatabase.getInstance().getReference();
    }
    @Override
    protected void onStart() {
        super.onStart();
        //attaching value event listener
        mDatabase.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {

                //clearing the previous artist list
               // users.clear();

                //iterating through all the nodes
                for (DataSnapshot postSnapshot : dataSnapshot.getChildren()) {
                    //getting artist
                    User user = postSnapshot.getValue(User.class);
                    //adding artist to the list.
                    users.add(user);
                }

                //creating adapter
                User_list userAdapter = new User_list(FireBase1.this, users);
                //attaching adapter to the listview
                lv.setAdapter(userAdapter);
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {
                System.out.println("The read failed: " + databaseError.getCode());
            }
        });
    }
}

我的尝试：



我试图从已存储的Firebase检索用户数据

What I have tried:

I have tried to retrieve users data from Firebase which was already stored

推荐答案

首先要做的事情。



调试并检查DataSnapshot getValue是否获取数据。如果已检索到记录，请继续检查适配器部件。如果您还有记录，则检查UI布局是否缺少任何高度或方向。

First things first .

Debug and check your DataSnapshot getValue fetches data. If it has records retrieved proceed to check the Adapter part. If there also you have records then check the UI Layout whether any height or orientation is missing .

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