Android ListView＆ArrayAdapter错误

我正在创建一个应用程序，它从JSON本地服务器中提取预订并将它们显示在ListView中。Android ListView＆ArrayAdapter错误

我设法拉出数据并显示在一个基地List格式，但决定创建一个更好看的List。我一直在遵循ezzylearning的指南，该指南为ListView增加了更多元素。

我已经检查了代码并搜索了一下，但我仍然在某种形式下遇到了ListView错误。不知道如何解决或调试此问题。

Ignition.java（mainActivity）：

package com.systematix.sxConcept; 


import java.io.BufferedReader; 
import java.io.IOException; 
import java.io.InputStream; 
import java.io.InputStreamReader; 

import org.apache.http.HttpEntity; 
import org.apache.http.HttpResponse; 
import org.apache.http.StatusLine; 
import org.apache.http.client.ClientProtocolException; 
import org.apache.http.client.HttpClient; 
import org.apache.http.client.methods.HttpGet; 
import org.apache.http.impl.client.DefaultHttpClient; 
import org.json.JSONArray; 
import org.json.JSONObject; 

import android.app.Activity; 
import android.os.AsyncTask; 
import android.os.Bundle; 
import android.util.Log; 
import android.view.Menu; 
import android.view.View; 
import android.widget.ListView; 


public class Ignition extends Activity { 

    // url to make request 
    private static String url = "http://10.0.0.103/android/data"; 

    public String company; 
    public String course; 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_ignition); 
     new ReadJSONFeedTask().execute(url); 
    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     getMenuInflater().inflate(R.menu.activity_ignition, menu); 
     return true; 
    } 

    public String readJSONFeed(String URL){ 
     StringBuilder stringBuilder = new StringBuilder(); 
     HttpClient client = new DefaultHttpClient(); 
     HttpGet httpget = new HttpGet(URL); 
     try{ 
      HttpResponse response = client.execute(httpget); 
      StatusLine statusLine = response.getStatusLine(); 
      int statusCode = statusLine.getStatusCode(); 
      if(statusCode == 200){ 
       HttpEntity entity = response.getEntity(); 
       InputStream content = entity.getContent(); 
       BufferedReader reader = new BufferedReader(
         new InputStreamReader(content)); 
       String line; 
       while ((line = reader.readLine()) != null){ 
        stringBuilder.append(line); 
       } 
      }else{ 
       Log.e("JSON", "Failed to download list"); 
      } 
     } catch (ClientProtocolException e){ 
      e.printStackTrace(); 
     } catch (IOException e){ 
      e.printStackTrace(); 
     } 

     return stringBuilder.toString(); 
    } 

    private class ReadJSONFeedTask extends AsyncTask<String, Void, String> { 
     protected String doInBackground(String... urls){ 
      return readJSONFeed(urls[0]); 
     } 

     protected void onPostExecute(String result){ 
      try{ 
       JSONArray jsonArray = new JSONArray(result); 
       Log.i("JSON", "Number of surveys in feed :" + jsonArray.length()); 
       ListView listView = (ListView) findViewById(R.id.listView1); 

       /*String[] responseList;   
       responseList = new String[jsonArray.length()];*/ 

       Bookings[] booking_data; 
       booking_data = new Bookings[jsonArray.length()]; 

       for (int i =0; i < jsonArray.length(); i++){ 
        JSONObject jsonObject = jsonArray.getJSONObject(i); 

        booking_data[i] = new Bookings(jsonObject.getString("Company"),jsonObject.getString("CourseTitle")); 

        //responseList[i] = jsonObject.getString("bookdate") + " - " + jsonObject.getString("Company"); 
       } 

       BookingsAdapter adapter = new BookingsAdapter(getBaseContext(), 
         R.layout.listview_item_row, booking_data); //export the data to a custom adapter 

       /* View header = (View)getLayoutInflater().inflate(R.layout.listview_header_row, null); 
       listView.addHeaderView(header);*/ 

       listView.setAdapter(adapter); 

       /*ArrayAdapter<String> newAdapter = new ArrayAdapter<String>(getBaseContext(), android.R.layout.test_list_item, responseList); 
       listView.setAdapter(newAdapter);*/ 

      } catch (Exception e){ 
       e.printStackTrace(); 
      } 
     } 
    } 

}

BookingsAdapter.java：

package com.systematix.sxConcept; 

import android.app.Activity; 
import android.content.Context; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.ArrayAdapter; 
import android.widget.TextView; 

public class BookingsAdapter extends ArrayAdapter<Bookings>{ 

    Context context; 
    int layoutResourceId; 
    Bookings data[] = null; 

    public BookingsAdapter(Context context, int layoutResourceId, Bookings[] data) { 
     super(context, layoutResourceId, data); 
     this.layoutResourceId = layoutResourceId; 
     this.context = context; 
     this.data = data; 
    } 

     @Override 
     public View getView(int position, View convertView, ViewGroup parent) { 
      View row = convertView; 
      BookingHolder holder = null; 

      if(row == null) 
      { 
       LayoutInflater inflater = ((Activity)context).getLayoutInflater(); 
       row = inflater.inflate(layoutResourceId, parent, false); 

       holder = new BookingHolder(); 
       holder.company = (TextView)row.findViewById(R.id.rowCompany); 
       holder.course = (TextView)row.findViewById(R.id.rowCourse); 

       row.setTag(holder); 
      } 
      else 
      { 
       holder = (BookingHolder)row.getTag(); 
      } 

      Bookings booking = data[position]; 
      holder.company.setText(booking.company); 
      holder.course.setText(booking.course); 

      return row; 
     } 

     static class BookingHolder 
     { 
      TextView company; 
      TextView course; 
     } 
    }

Bookings.java：

package com.systematix.sxConcept; 

public class Bookings { 
    public String company; 
    public String course; 
    public Bookings(){ 
     super(); 
    } 

    public Bookings(String company, String course) { 
     super(); 
     this.company = company; 
     this.course = course; 
    } 
}

XML布局文件是教程中看到的1的副本，图标替换为Textview。

这些都是错误的：

07-24 12:36:10.154: E/AndroidRuntime(331): FATAL EXCEPTION: main 
07-24 12:36:10.154: E/AndroidRuntime(331): java.lang.ClassCastException: android.app.ContextImpl 
07-24 12:36:10.154: E/AndroidRuntime(331): at com.systematix.sxConcept.BookingsAdapter.getView(BookingsAdapter.java:31) 
07-24 12:36:10.154: E/AndroidRuntime(331): at android.widget.HeaderViewListAdapter.getView(HeaderViewListAdapter.java:220) 
07-24 12:36:10.154: E/AndroidRuntime(331): at android.widget.AbsListView.obtainView(AbsListView.java:1430) 
07-24 12:36:10.154: E/AndroidRuntime(331): at android.widget.ListView.makeAndAddView(ListView.java:1745) 
07-24 12:36:10.154: E/AndroidRuntime(331): at android.widget.ListView.fillDown(ListView.java:670) 
07-24 12:36:10.154: E/AndroidRuntime(331): at android.widget.ListView.fillFromTop(ListView.java:727) 
07-24 12:36:10.154: E/AndroidRuntime(331): at android.widget.ListView.layoutChildren(ListView.java:1598) 
07-24 12:36:10.154: E/AndroidRuntime(331): at android.widget.AbsListView.onLayout(AbsListView.java:1260) 
07-24 12:36:10.154: E/AndroidRuntime(331): at android.view.View.layout(View.java:7175) 
07-24 12:36:10.154: E/AndroidRuntime(331): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1254) 
07-24 12:36:10.154: E/AndroidRuntime(331): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1130) 
07-24 12:36:10.154: E/AndroidRuntime(331): at android.widget.LinearLayout.onLayout(LinearLayout.java:1047) 
07-24 12:36:10.154: E/AndroidRuntime(331): at android.view.View.layout(View.java:7175) 
07-24 12:36:10.154: E/AndroidRuntime(331): at android.widget.FrameLayout.onLayout(FrameLayout.java:338) 
07-24 12:36:10.154: E/AndroidRuntime(331): at android.view.View.layout(View.java:7175) 
07-24 12:36:10.154: E/AndroidRuntime(331): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1254) 
07-24 12:36:10.154: E/AndroidRuntime(331): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1130) 
07-24 12:36:10.154: E/AndroidRuntime(331): at android.widget.LinearLayout.onLayout(LinearLayout.java:1047) 
07-24 12:36:10.154: E/AndroidRuntime(331): at android.view.View.layout(View.java:7175) 
07-24 12:36:10.154: E/AndroidRuntime(331): at android.widget.FrameLayout.onLayout(FrameLayout.java:338) 
07-24 12:36:10.154: E/AndroidRuntime(331): at android.view.View.layout(View.java:7175) 
07-24 12:36:10.154: E/AndroidRuntime(331): at android.view.ViewRoot.performTraversals(ViewRoot.java:1140) 
07-24 12:36:10.154: E/AndroidRuntime(331): at android.view.ViewRoot.handleMessage(ViewRoot.java:1859) 
07-24 12:36:10.154: E/AndroidRuntime(331): at android.os.Handler.dispatchMessage(Handler.java:99) 
07-24 12:36:10.154: E/AndroidRuntime(331): at android.os.Looper.loop(Looper.java:123) 
07-24 12:36:10.154: E/AndroidRuntime(331): at android.app.ActivityThread.main(ActivityThread.java:3683) 
07-24 12:36:10.154: E/AndroidRuntime(331): at java.lang.reflect.Method.invokeNative(Native Method) 
07-24 12:36:10.154: E/AndroidRuntime(331): at java.lang.reflect.Method.invoke(Method.java:507) 
07-24 12:36:10.154: E/AndroidRuntime(331): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 
07-24 12:36:10.154: E/AndroidRuntime(331): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 
07-24 12:36:10.154: E/AndroidRuntime(331): at dalvik.system.NativeStart.main(Native Method)

来源

2012-07-24 Will Watson

试试这个

BookingsAdapter adapter = new BookingsAdapter(Ignition.this, 
        R.layout.listview_item_row, booking_data);

来源

2012-07-24 13:39:54

试着这样做：

LayoutInflater li = LayoutInflater.from(context);

或

LayoutInflater li = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

我假设这是行号：31，其中class cast exception发生。

来源

2012-07-24 13:42:24 Shrikant

线

LayoutInflater inflater = ((Activity)context).getLayoutInflater();

你是铸造上下文活动。活动从Context继承，所以你不需要这个转换。试试这个，而不是

LayoutInflater inflater = LayoutInflater inflater = LayoutInflater inflater = 
          context.getLayoutInflater();

来源

2012-07-24 13:45:14

Android ListView＆ArrayAdapter错误

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