如何使用 Firebase 列表适配器 [英] How to use Firebase List adapter

问题描述

我正在尝试学习本教程:

I'm trying to follow with this tutorial:

https://www.youtube.com/watch?v=2J6spwAVP0M

但是在我复杂的应用程序上实现它并没有奏效，所以我从头开始尝试..

but implementing it on my complex app just didn't work so I tried from scratch..

我创建了这个简单的 MainActivity:

I created this simple MainActivity:

public class MainActivity extends AppCompatActivity{

    Firebase mRef;
    com.firebase.ui.FirebaseListAdapter<String> myAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mRef = new Firebase("https://<myURL>..");

        myAdapter = new FirebaseListAdapter<String>(this,String.class,android.R.layout.simple_list_item_1,mRef) {
            @Override
            protected void populateView(View view, String s, int i) {
                TextView text = (TextView)view.findViewById(android.R.id.text1);
                text.setText(s);

            }
        };
        Button addBtn = (Button) findViewById(R.id.add_button);
        addBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                mRef.push().setValue("test123");
            }
        });
    }
}

现在我有几个问题:

1) 是什么触发了 populateView?我只是无法让它运行

1) what triggers the populateView? I just couldn't make it run

2) android.R.layout.simple_list_item_1 究竟应该用什么替换?我尝试创建自己的列表视图并用我的 R.id.listView 替换上面的内容，但没有任何反应.. 我不知道这个魔法是如何工作的..

2) what exactly should the android.R.layout.simple_list_item_1 be replaced with? I tried creating my own listview and replace the above with my R.id.listView but nothing happens.. I can't figure out how this magic works..

3) 即使这个简单的应用程序也不起作用..该按钮确实将test123"添加到服务器上的正确位置，但我在我的应用程序上看不到任何内容..怎么了?

3) even this simple app didn't work.. the button does add the "test123" to the right place on the server but I see nothing on my app.. whats wrong?

推荐答案

我发现出了什么问题，我缺少一个 Listview..这是更正后的代码:

I found out what was wrong, I was missing a Listview.. Heres the corrected code:

public class MainActivity extends AppCompatActivity {

    Firebase mRef;
    com.firebase.ui.FirebaseListAdapter<String> myAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mRef = new Firebase("https://<myURL>..");

        myAdapter = new FirebaseListAdapter<String>(this,String.class,android.R.layout.simple_list_item_1,mRef) {
            @Override
            protected void populateView(View view, String s, int i) {
                TextView text = (TextView) view.findViewById(android.R.id.text1);
                text.setText(s);
            }
        };
        final ListView lv = (ListView) findViewById(R.id.listView);
        lv.setAdapter(myAdapter);

        Button addBtn = (Button) findViewById(R.id.add_button);
        addBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                mRef.push().setValue("test123");
            }
        });
    }


}

lv.setAdapter 是将适配器关联到我的列表并触发 populateView 的东西.这基本上是对我所有 3 个问题的一次回答..

the lv.setAdapter is what associating the adapter to my list and also triggers the populateView.. That's basically the answer to all of my 3 questions at once..

这里也是xml:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.twodwarfs.firebaselistadapter.MainActivity">


    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="add"
        android:id="@+id/add_button"
        android:layout_alignParentBottom="true"
        android:layout_alignParentEnd="true" />

    <ListView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/listView"
        android:layout_toStartOf="@+id/add_button"
        android:layout_below="@+id/textView" />
</RelativeLayout>

这篇关于如何使用 Firebase 列表适配器的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！