Listview BaseAdapter 数据未显示

Posted 2023-05-07

【中文标题】Listview BaseAdapter 数据未显示

【英文标题】：Listview BaseAdapter Data not being shown

【发布时间】：2015-09-26 00:23:06

【问题描述】：

我正在尝试使用 BaseAdapter 填充列表视图，我遇到的问题是显示数据的文本视图，拒绝实际绘制文本。 我在 textview 上调用了 getText()，它确实显示了正确的信息，但是由于某种原因，它根本没有被渲染。

自定义适配器：

public class CardListviewAdapter extends BaseAdapter 


private Context context;
private ArrayList<String> numbers;
private LayoutInflater layoutInflater;


public CardListviewAdapter(Context context, ArrayList<String> numbers) 

    this.context = context;
    this.numbers = numbers;
    layoutInflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);



@Override
public int getCount() 
    return numbers.size();


@Override
public Object getItem(int position) 
    return numbers.get(position);


@Override
public long getItemId(int position) 
    return 0;


@Override
public View getView(int position, View convertView, ViewGroup parent) 


    ViewHolder holder = new ViewHolder();
    if(convertView == null)
    
        Log.i("Inflating","Inflating Layout...");
        convertView = layoutInflater.inflate(R.layout.conversation,null);

    
    holder.numbers = (TextView)convertView.findViewById(R.id.numbertitle);

    Log.e("Number",holder.numbers.toString());
    convertView.setTag(holder);

    Log.i("Item:", "" + numbers.get(position));
    holder.numbers.setText(numbers.get(position));


    return convertView;


public final class ViewHolder

    public TextView numbers;

主活动：

public class ConversationThreads extends AppCompatActivity 


private ListView listview;
CardListviewAdapter adapter;

@Override
protected void onCreate(Bundle savedInstanceState) 
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_conversation_threads);
    this.listview = (ListView)findViewById(R.id.conversationListview);
    populateConversations();


@Override
public boolean onCreateOptionsMenu(Menu menu) 
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_conversation_threads, menu);
    return true;


@Override
public boolean onOptionsItemSelected(MenuItem item) 
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in androidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) 
        return true;
    

    return super.onOptionsItemSelected(item);



private void populateConversations()

    Log.d("Populate", "Populating...");

    //Array of Strings returned -- Target Data

    ArrayList<String> numbers = TSMS.getConversationNumbers(getApplicationContext());
    adapter = new CardListviewAdapter(getApplicationContext(),numbers);
    listview.setAdapter(adapter);

Listview.xml 布局：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_
android:layout_ android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:layout_gravity="center_horizontal"
android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".CThreads"
android:id="@+id/conversationThreadLayout">

<ListView
    android:layout_
    android:layout_
    android:id="@+id/conversationListview" />
</RelativeLayout>

conversation.xml 布局：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_ android:layout_
android:background="@drawable/bg_card">

<TextView
    android:layout_
    android:layout_
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:text="Large Text"
    android:id="@+id/numbertitle"
    android:layout_alignParentTop="true"
    android:layout_alignParentStart="true" />

<TextView
    android:layout_
    android:layout_
    android:textAppearance="?android:attr/textAppearanceMedium"
    android:text="Medium Text"
    android:id="@+id/lastmessage"
    android:layout_below="@+id/numbertitle"
    android:layout_centerHorizontal="true" />
</RelativeLayout> 

编辑：修复了 Listview ID 错误，但结果未更改。Edit2：问题是白色背景列表视图和白色文本。 回复@N1to，在 cmets 中提供。

【问题讨论】：

您的列表视图参考​​是 R.id.conversationListview。此外，在 onCreate

中初始化您的 ArrayList 对象

感谢@m0rpheu5，但是数据仍然没有显示在列表视图项目中。

【参考方案1】：

你有代码：

this.listview = (ListView)findViewById(R.id.Listview);

在您的 XML 中，您的 id 是不同的：

<ListView
    android:layout_
    android:layout_
    android:id="@+id/conversationListview" />

另外，把它移到你的activity_conversation_threads.xml，它不需要单独的布局。

---

添加到类 `ConversationThreads:

private ArrayList<String> numbers;
private CardListviewAdapter adapter;

然后将您的方法更改为：

private void populateConversations()

    Log.d("Populate", "Populating...");

    //Array of Strings returned -- Target Data

    numbers = TSMS.getConversationNumbers(getApplicationContext());

    Log.d("ArrayList size", String.valueOf(numbers.size()); // check if it returns non zero

    adapter = new CardListviewAdapter(getApplicationContext(),numbers);
    listview.setAdapter(adapter);

---

适配器代码

public class CardListViewAdapter extends BaseAdapter 
    private Context context;
    private ArrayList<String> numbers;


    public CardListViewAdapter(Context context, ArrayList<String> numbers) 

        this.context = context;
        this.numbers = numbers;

    

    @Override
    public int getCount() 
        return numbers.size();
    

    @Override
    public Object getItem(int position) 
        return numbers.get(position);
    

    @Override
    public long getItemId(int position) 
        return 0;
    

    @Override
    public View getView(int position, View convertView, ViewGroup parent) 
        View rowView = convertView;

        if (rowView == null) 
            LayoutInflater layoutInflater = LayoutInflater.from(context);
            rowView = layoutInflater.inflate(R.layout.conversation, null);
            ViewHolder viewHolder = new ViewHolder(rowView);
            rowView.setTag(viewHolder);
        

        final ViewHolder holder = (ViewHolder) rowView.getTag();

        holder.numbers.setText(numbers.get(position));

        return rowView;
    

    public class ViewHolder 

        private final TextView numbers;

        public ViewHolder(View v) 
            this.numbers = (TextView) v.findViewById(R.id.numbertitle);
        
    

【讨论】：

感谢回复，我已经调整了ListView ID的错误，并检查了arraylist的大小，（它是正确的大小）和内容（也正确）。但是文本仍然没有呈现。感谢列表视图修复。

试试我的适配器并告诉结果。

我试过你提供的适配器，很遗憾结果没有变化。

所以它在内存中，但它不显示。您是否尝试使用不同的背景、字体颜色等来确保您没有出现“白色背景上的白色文字”的情况？

我的上帝....我不敢相信我没有想到白色背景上的白色文字，是的，这就是问题所在，非常感谢@N1to :)