填充微调器时出错

Question

我正在尝试从JSON响应中填充微调器。在两个微调器之后，我正在尝试读取JSON并填充它。但它没有发生。我的代码在

之下

public class MainActivity extends Activity {

    InputStream is=null;
    String result=null;
    String line=null;

    String[] roll_no,name;  

    Spinner spinner1,spinner2;
    final List<String> list1 = new ArrayList<String>();
    final List<String> list2 = new ArrayList<String>();   


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

    spinner1 = (Spinner) findViewById(R.id.spinner1);
    spinner2 = (Spinner) findViewById(R.id.spinner2);


    Button b=(Button) findViewById(R.id.button1);

    b.setOnClickListener(new View.OnClickListener() {

    @Override
    public void onClick(View v)
    {
        new insertTask().execute("");


    }
    });

    }


    private void spinner_fn() {
    // TODO Auto-generated method stub

    ArrayAdapter<String> dataAdapter1 = new ArrayAdapter<String>(getApplicationContext(),
                                    android.R.layout.simple_spinner_item, roll_no);
    dataAdapter1.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spinner1.setAdapter(dataAdapter1);


    ArrayAdapter<String> dataAdapter2 = new ArrayAdapter<String>(getApplicationContext(),
                                    android.R.layout.simple_spinner_item, name);
    dataAdapter2.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spinner2.setAdapter(dataAdapter2);


    spinner1.setOnItemSelectedListener(new OnItemSelectedListener()
    {
    @Override
    public void onItemSelected(AdapterView<?> arg0, View arg1,int position, long id)
    {
    // TODO Auto-generated method stub

    spinner2.setSelection(position);

    }

    @Override
    public void onNothingSelected(AdapterView<?> arg0)
    {
    // TODO Auto-generated method stub
    }

    });


    spinner2.setOnItemSelectedListener(new OnItemSelectedListener() {

    @Override
    public void onItemSelected(AdapterView<?> arg0, View arg1,int position, long arg3) {
    // TODO Auto-generated method stub

    spinner1.setSelection(position);

    }

    @Override
    public void onNothingSelected(AdapterView<?> arg0) {
    // TODO Auto-generated method stub
    }
    });

    }



class insertTask extends AsyncTask<String, String, String> {
    protected String doInBackground(String... params) {
        String result = insert();
        return result ;
    }


    protected void onPostExecute(String result) {
        if(result.equals("OK")){
            Toast.makeText(getBaseContext(), "Value Added",
                    Toast.LENGTH_LONG).show();
        }
        //after background is done, use this to show or hide dialogs
    }
}

public String insert()
{
    try
    {
    HttpClient httpclient = new DefaultHttpClient();
    HttpPost httppost = new HttpPost("http://122.181.3.82:4007/CatchInfo/values");
    HttpResponse response = httpclient.execute(httppost);
    Log.e("Fail 1", "3");

    HttpEntity entity = response.getEntity();
    Log.e("Fail 1", "4");

    is = entity.getContent();
    Log.e("Pass 1", "connection success ");
    }
    catch(Exception e)
    {
    Log.e("Fail 1", e.toString());
    Toast.makeText(getApplicationContext(), "Invalid IP Address",Toast.LENGTH_LONG).show();
    finish();
    }    


    try
    {
    BufferedReader reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
    StringBuilder sb = new StringBuilder();
    while ((line = reader.readLine()) != null)
    {
    sb.append(line + "\n");
    }
    is.close();
    result = sb.toString();
    }
    catch(Exception e)
    {
    Log.e("Fail 2", e.toString());
    }    


    try
    {       

    JSONArray JA=new JSONArray(result);
    JSONObject json= null;
    roll_no = new String[JA.length()];       
    name = new String[JA.length()];


    for(int i=0;i<JA.length();i++)
    {
    json=JA.getJSONObject(i);
    roll_no[i] = json.getString("roll_no");
    name[i]=json.getString("name");
    }
    Toast.makeText(getApplicationContext(), "sss",Toast.LENGTH_LONG).show();

    for(int i=0;i<roll_no.length;i++)
    {
    list1.add(roll_no[i]);
    list2.add(name[i]);
    }

    spinner_fn();

    }
    catch(Exception e)
    {

    Log.e("Fail 3", e.toString());
    //login.this.finish();

    }
    return result;
}


}

但是我收到这样的错误：

05-22 19:10:29.381: E/Fail 1(2136): 3
05-22 19:10:29.381: E/Fail 1(2136): 4
05-22 19:10:29.381: E/Pass 1(2136): connection success 
05-22 19:10:29.451: E/Fail 3(2136): java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()

请帮帮我。