Android:自定义ArrayAdapter不能显示文本

Question

我正在一个Android项目上工作，在那里我想创建一个CustomArray适配器来首先显示我从服务器获得的餐厅名称，当用户单击其中一个对象时，然后它的id在后端检索(未显示，UI上没有任何内容)。目前，我有一些问题，因为它不工作。

注意请注意，我不是一个Android程序员，如果你能帮助我，我会非常感激，但请试着理解，我不是那么熟悉Android的概念，所以我可能不完全理解你想说什么，可能有一些后续的评论。如果你有时间，请贴一个简单的方式与代码的答案。对不起，但我只是有类似的问题，这不是一个很好的经验。谢谢。如果我无礼的话，我很抱歉，但我觉得这很重要。

布局代码:

<?xml version="1.0" encoding="UTF-8"?>
<ListView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@android:id/list"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >
</ListView>

这是餐厅类:

public class RestRestaurant {
    private int restaurantId;
    private String restaurantName;
//getters and setters ommitted;
}

最后是活动代码:

public class RestaurantList extends ListActivity {
    String restaurantList = "http://192.168.178.60:8080/restaurant/listing";
    private ResponseEntity<RestRestaurant[]> responseEntity;
    private OrderAdapter m_adapter;
    private ArrayList<RestRestaurant> m_orders = null;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.restos);
        RestTemplate restTemplate = StaticRestTemplate.getRest();
        Thread thread = new Thread(new Runnable() {
            @Override
            public void run() {
                HttpHeaders requestHeaders = new HttpHeaders();
                requestHeaders.add("Cookie", "JSESSIONID=" + StaticRestTemplate.jsessionid);
                requestHeaders.setAccept(Collections.singletonList(new MediaType("application", "json")));
                HttpEntity<?> requestEntity = new HttpEntity<Object>(requestHeaders);
                restTemplate.getMessageConverters().add(new MappingJackson2HttpMessageConverter());
                responseEntity= restTemplate.exchange(restaurantList, HttpMethod.GET,requestEntity,RestRestaurant[].class);
            }
        });
        thread.start();
        ProgressDialog progress = new ProgressDialog(this);
        progress.setTitle("Loading");
        progress.setMessage("Wait while loading...");
        while (thread.getState()!=Thread.State.TERMINATED){
            progress.show();
        }
        progress.dismiss();
        RestRestaurant[] restRestaurantList = responseEntity.getBody();
        m_orders = new ArrayList<RestRestaurant>();
        this.m_adapter = new OrderAdapter(this, android.R.layout.simple_list_item_1, m_orders);
        for (RestRestaurant restRestaurant1 : restRestaurantList){
            m_adapter.add(restRestaurant1);
        }
        setListAdapter(this.m_adapter);
    }

    private class OrderAdapter extends ArrayAdapter<RestRestaurant> {
        private ArrayList<RestRestaurant> items;
        public OrderAdapter(Context context, int textViewResourceId, ArrayList<RestRestaurant> items) {
            super(context, textViewResourceId, items);
            this.items = items;
        }
        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            View v = convertView;
            RestRestaurant o = items.get(position);
            Log.d("Restaurant id is ",String.valueOf(o.getRestaurantId()));
            return v;
        }
    }
    @Override
    public void onBackPressed()
    {
        Intent intent = new Intent(RestaurantList.this, Login.class);
        StaticRestTemplate.jsessionid = null;
        StaticRestTemplate.replyString = null;
        startActivity(intent);
        finish();
    }
}

错误日志:

07-14 11:23:52.690    1534-1543/android.process.acore E/StrictMode﹕ A resource was acquired at attached stack trace but never released. See java.io.Closeable for information on avoiding resource leaks.
    java.lang.Throwable: Explicit termination method 'close' not called
            at dalvik.system.CloseGuard.open(CloseGuard.java:184)

请理解，我只想显示餐厅的名字，点击后在activity类中取回Id，剩下的事情我自己来处理。非常感谢。

更新

row.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">
</LinearLayout>

错误日志:

07-15 10:25:13.951    2666-2666/com.example.TestLunch E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.example.TestLunch, PID: 2666
    java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
            at com.example.TestLunch.Activity.RestaurantList$OrderAdapter.getView(RestaurantList.java:125)

出现在这里:

RestRestaurant item = getItem(position);
            if (item != null) {
// on below line
                holder.tvRestourantName.setText(item.getRestaurantName());
            }

Answer 1

这个错误意味着您打开了某些东西而没有关闭它。接口Closable提供了方法close()，您应该调用该方法来释放不再需要的资源。

你可以看看这里，检查你是否正在使用一些类实现Closable

getView()的正确实现是:

public View getView(int position, View convertView, ViewGroup parent) { 
    View rowView = convertView;
    ViewHolder holder;
    if(rowView == null){
        LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);           
        rowView = inflater.inflate(R.layout.custom_row_layout, parent, false);
        holder = new ViewHolder(); 
        holder.tvRestourantName= (TextView) rowView.findViewById(R.id.restourant_name); // restourant_name is the ID of the view inside yout custom layout 
        rowView.setTag(holder); 
    }else{
        holder = (ViewHolder) rowView.getTag(); 
    }
    Contact item = getItem(position);
    if (item!= null) {
        holder.tvRestourantName.setText(item.getRestourantName());
    }
    return rowView;
}
static class ViewHolder { 
    TextView tvRestourantName; 
}

您需要在单独的XML文件中定义列表内行的布局。我把它命名为custom_row_layout.xml

然后在你的列表中你需要设置一个点击监听器:

getListView().setOnItemClickListener(new OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                  RestRestaurant item = (RestRestaurant)getListView().getAdapter().getItem(position);
                  int id = item.getRestaurantId(); // now you have the ID
            }
        });