Java 很遗憾，myapp已停止消息

我使用JSON在android中编写了一个客户机-服务器通信代码。我使用的是WAMP服务器，PHP文件中没有错误。当我运行我的应用程序模拟器时，会显示“不幸的是，我的应用程序已停止”。请给我一些建议。我试着去解决，但我做不到。 我的java文件：

package com.example.http;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;



import android.app.ListActivity;
import android.net.ParseException;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends ListActivity {

JSONArray jArray;
String result = null;
InputStream is = null;
StringBuilder sb=null;
TextView tv;


@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

 ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
//http post
try{
     HttpClient httpclient = new DefaultHttpClient();
     HttpPost httppost = new HttpPost("http://10.0.2.2/android_connect/read1.php");
     httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
     HttpResponse response = httpclient.execute(httppost);
     HttpEntity entity = response.getEntity();
     is = entity.getContent();
     }catch(Exception e){
         Log.e("log_tag", "Error in http connection"+e.toString());
    }
//convert response to string
try{
      BufferedReader reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
       sb = new StringBuilder();
       sb.append(reader.readLine() + "\n");

       String line="0";
       while ((line = reader.readLine()) != null) {
                      sb.append(line + "\n");
        }
        is.close();
        result=sb.toString();
        }catch(Exception e){
              Log.e("log_tag", "Error converting result "+e.toString());
        }
//paring data

try{
      jArray = new JSONArray(result);
      JSONObject json_data=null;
      for(int i=0;i<jArray.length();i++){
             json_data = jArray.getJSONObject(i);
             String ct_name = json_data.getString("User_ID");
             tv = (TextView) findViewById(R.id.textView1);

             tv.setText(ct_name);

         }
      }
      catch(JSONException e1){
          Toast.makeText(getBaseContext(), "No City Found" ,Toast.LENGTH_LONG).show();
      } catch (ParseException e1) {
            e1.printStackTrace();
    }
}
}

您的内容必须具有

ListView

，其

id

属性为“android.R.id.list”

您的R.layout.activity\u main没有listview元素

---

PS：在扩展

ListActivity

并提供自定义布局时，您不应该在主线程read about上使用网络请求，您必须将以下Id设置为xml格式的

ListView

——在本例中设置为

活动\u main

android:id="@android:id/list"

---

顺便说一句，异常本身已经足够解释了。

从错误消息中：

04-21 22:43:33.502: E/AndroidRuntime(399): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.http/com.example.http.MainActivity}: java.lang.RuntimeException: Your content must have a ListView whose id attribute is 'android.R.id.list'

您的“activity_main.xml”可能没有id为“android.R.id.list”的属性。 因为您的活动扩展了“ListActivity”，所以应该包含它

android:id="@android:id/list"

04-21 22:43:33.502: E/AndroidRuntime(399): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.http/com.example.http.MainActivity}: java.lang.RuntimeException: Your content must have a ListView whose id attribute is 'android.R.id.list'