Php 分析数据java.lang.NullPointerExceptionnull时出错

我已经能够将下面的PHP代码用于其他活动，它工作得很好，但是对于这个特定的活动，它给了我一个空指针异常

这是我的密码

    public void getData(List<? extends NameValuePair> namevalue) {
        // TODO Auto-generated method stub
        String result = "";
             InputStream isr = null;
             try
             {
             HttpClient httpclient = new DefaultHttpClient();
             HttpPost httppost = new HttpPost("http://10.0.2.2/view.php");
             httppost.setEntity(new UrlEncodedFormEntity(namevalue));
             HttpResponse response = httpclient.execute(httppost);
             HttpEntity entity = response.getEntity();
             isr = entity.getContent();
             }
             catch(Exception e)
             {
             Log.e("log_tag", "Error in http connection "+e.toString());
             e2.setText("Couldnt connect to database");
             }
             //convert response to string

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

             result=sb.toString();

             }
             catch(Exception e)
             {
             Log.e("log_tag", "Error converting result "+e.toString());
             }
             try
                {  String usn=null;
                 String g=null  ;
                 String dob=null;
                 String yop=null;
                 String email=null;
                 String phone = null;
                 String tenyop = null;
                 String tenp=null;
                 String twelyop=null;
                 String twelp=null;
                 String dipyop=null;
                 String dipp=null;
                 String branch=null;
                 String s1=null;
                 String s2=null;
                 String s3=null;
                 String s4=null;
                 String s5=null;
                 String s6=null;
                 String s7=null;
                 String s8=null;
                 String fa=null;
                 String back=null;
                 String aggre=null;


                 JSONArray jArray =  new JSONArray(result);
                 for(int i=0; i<jArray.length();i++)
                 {
                 JSONObject json = jArray.getJSONObject(i);
                 usn = " "+json.getString("usn")+"\n";
                 g= " "+json.getString("gender")+"\n";
                 yop=" "+json.getString("yop")+"\n";
                 dob = dob + " "+json.getString("dob")+"\n";
                 email=" "+json.getString("email")+"\n";
                 phone=" "+json.getString("phone_no")+"\n";
                 tenyop =" "+json.getString("tenyop")+"\n";
                 tenp= " "+json.getString("tenperc")+"\n";
                 twelyop=" "+json.getString("twelveyop")+"\n";
                 twelp = " "+json.getString("twelveperc")+"\n";
                 dipyop= " "+json.getString("dipyop")+"\n";
                 dipp= " "+json.getString("dipperc")+"\n";
                 branch= " "+json.getString("branch")+"\n";
                 s1= " "+json.getString("sem1")+"\n";
                 s2=  " "+json.getString("sem2")+"\n";
                 s3=  " "+json.getString("sem3")+"\n";
                 s4=  " "+json.getString("sem4")+"\n";
                 s5=  " "+json.getString("sem5")+"\n";
                 s6=  " "+json.getString("sem6")+"\n";
                 s7=  " "+json.getString("sem7")+"\n";
                 s8=  " "+json.getString("sem8")+"\n";
                 fa=  " "+json.getString("fa")+"\n";
                 back= " "+json.getString("back")+"\n";
                 //aggre=" "+json.getString("aggregate")+"\n";
                }

                 e2.setText(dob);

                 e3.setText(phone);
                 e4.setText(tenyop);
                 e5.setText(tenp);
                 e6.setText(twelyop);
                 e7.setText(twelp);
                 e8.setText(dipyop);
                 e9.setText(dipp);
                 sem1.setText(s1);
                 sem2.setText(s2);
                 sem3.setText(s3);
                 sem4.setText(s4);
                 sem5.setText(s5);
                 sem6.setText(s6);
                 sem7.setText(s7);
                 sem8.setText(s8);
                 e10.setText(fa);
                 e11.setText(back);
                }
   catch (Exception e) 
   {
     Log.e("log_tag1", "Error Parsing Data "+e.toString());
       e.printStackTrace();
     }
     }  

---

请帮帮我。这对我的项目很重要格式化代码并发布StackTraceNull pointexception在哪里？请发布您的logcat。如果您的HTTP客户端代码块抛出错误，它将被记录、删除，然后继续读取null ISR变量。这就是你的NullPointerException的来源吗？请发布你的日志

<?php
    $con=mysql_connect("localhost","root","");
    if(!$con)
        die('could not connect: ' .mysql_error());
    mysql_select_db("portal",$con);
    $usn=$_POST['usn'];
    $result = mysql_query("SELECT *FROM LOGIN where usn='$usn'");
    while($row=mysql_fetch_assoc($result)) {
        $output[]=$row;
    }
    echo(json_encode($output));
    mysql_close($con);
?>

04-07 11:35:39.573: E/log_tag1(1058): Error Parsing Data java.lang.NullPointerException
04-07 11:35:39.603: W/System.err(1058): java.lang.NullPointerException
04-07 11:35:39.603: W/System.err(1058):     at com.example.app.Userpage.getData(Userpage.java:488)
04-07 11:35:39.613: W/System.err(1058):     at com.example.app.Userpage.onCreate(Userpage.java:92)
04-07 11:35:39.613: W/System.err(1058):     at android.app.Activity.performCreate(Activity.java:5231)
04-07 11:35:39.613: W/System.err(1058):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
04-07 11:35:39.613: W/System.err(1058):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
04-07 11:35:39.613: W/System.err(1058):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
04-07 11:35:39.613: W/System.err(1058):     at android.app.ActivityThread.access$800(ActivityThread.java:135)
04-07 11:35:39.613: W/System.err(1058):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
04-07 11:35:39.613: W/System.err(1058):     at android.os.Handler.dispatchMessage(Handler.java:102)
04-07 11:35:39.613: W/System.err(1058):     at android.os.Looper.loop(Looper.java:136)
04-07 11:35:39.613: W/System.err(1058):     at android.app.ActivityThread.main(ActivityThread.java:5017)
04-07 11:35:39.623: W/System.err(1058):     at java.lang.reflect.Method.invokeNative(Native Method)
04-07 11:35:39.623: W/System.err(1058):     at java.lang.reflect.Method.invoke(Method.java:515)
04-07 11:35:39.623: W/System.err(1058):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
04-07 11:35:39.623: W/System.err(1058):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
04-07 11:35:39.623: W/System.err(1058):     at dalvik.system.NativeStart.main(Native Method)