我想显示关于给定的 JSON url，但我无法正确声明 JSONObject 以及 JSONArray 在 MainActivity ，所以请任何人帮我在上面显示数据 TextView . 显示错误：
java.lang.runtimeexception:无法启动activity componentinfo{com.example.和\u ws\u builder/com.example.和\u ws\u builder.mainactivity}:android.os.networkonmainthreadexception
mainactivity.java类

public class MainActivity extends Activity {   
        private static String url ="http://myfourwalls.in/services_microsite/project_builder.php";
        private static final String TAG_Name = "about_builder";
        JSONArray builder = null;
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            JSONParser jParser = new JSONParser();        
            JSONObject json = jParser.getJSONFormUrl(url);        
            try {

                builder = json.getJSONArray(TAG_Name);
                 JSONObject c = builder.getJSONObject(0);

                for (int i = 0; i < json.length(); i++) {

                    String name = c.getString(TAG_Name);                
                    final TextView nam = (TextView) findViewById(R.id.txtname);
                    nam.setText(name);
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }
        }
    }

jsonparser.java文件

public class JSONParser {
     static InputStream is = null;
     static JSONObject jobj = null;
     static String json = "";
    public JSONParser() {
    }

    public JSONObject getJSONFormUrl(String url) {  
        try {
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(url);
            HttpResponse httpResponse = httpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();
            is = httpEntity.getContent();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }catch (ClientProtocolException e) {
            e.printStackTrace();
        }catch (IOException e) {
            e.printStackTrace();
        }

        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    is, "iso-8859-1"), 8);
            StringBuilder sb = new StringBuilder();
            String line = null;
            while ((line = reader.readLine()) != null ){
                sb.append(line +"\n");
            }
            is.close();
            json = sb.toString();

        } catch (Exception e) {
             Log.e("Buffer Error","Error converting result" + e.toString());
        }
        try {
            jobj = new JSONObject(json);

        } catch (JSONException e) {
            Log.e("JSON Parse","error Parsing data" + e.toString());
        }
        return jobj;
    }
}

主活动.xml

<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" >    
     <TextView 
         android:id="@+id/txtname"
         android:layout_width="fill_parent"
         android:layout_height="100dp"/>
</RelativeLayout>