android开发中提交json到数据库时出现的问题

public class Register_ extends Activity{
private EditText register_username;
private EditText register_passwd;
private EditText register_repasswd;
private Button registerBt;
private ProgressDialog pDialog;
JSONParser jsonParser=new JSONParser();
private String jsonData;
private String message;
private int success;
public static String url="192.168.1.203/EnjoyDemo/register.php";

@Override
protected void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     setContentView(R.layout.signup);


     register_username=(EditText)findViewById(R.id.editText1);
     register_username.requestFocus();
     register_passwd=(EditText)findViewById(R.id.editText2);
     register_repasswd=(EditText)findViewById(R.id.editText3);
     registerBt=(Button)findViewById(R.id.button1);


     registerBt.setOnClickListener(new OnClickListener() {

        @Override
         public void onClick(View v)
        { 
            if (register_username.getText().toString().equals("")||register_passwd.getText().toString().equals(""))
            {
                Toast toast=Toast.makeText(Register_.this, "请输入账号密码",Toast.LENGTH_SHORT);
                toast.show();

            }  else {      
                new Register().execute();

            }

        }


    });    
 }
class Register extends AsyncTask<String, String, String>
{
    @Override
    protected void onPreExecute(){
        super.onPreExecute();
        pDialog=new ProgressDialog(Register_.this);
        pDialog.setMessage("正在注册...");
        pDialog.setIndeterminate(false);
        pDialog.setCancelable(true);
        pDialog.show();
    }


    protected String doInBackground(String... args) {
        List<NameValuePair>params=new ArrayList<NameValuePair>();
        params.add(new BasicNameValuePair("username", register_username.getText().toString()));
        params.add(new BasicNameValuePair("password", register_passwd.getText().toString()));
        try{
            jsonData=jsonParser.makeHttpRequest(url, "POST", params);
        }catch(Exception e){
            e.printStackTrace();
        }
        try {
            JSONObject jsonObject=new JSONObject(jsonData);

            message=jsonObject.getString("message");
            success=jsonObject.getInt("success");

        } catch (JSONException e) {
            // TODO Auto-generated catch block
            Log.e("long_tag","Error parsing data"+e.toString());
        }

        return null;
    }
    protected void onPostExecute(String file_url){
        pDialog.dismiss();
        String str=""+success;
        Toast toast=Toast.makeText(Register_.this, "返回码="+str+":"+message, Toast.LENGTH_LONG);
        toast.show();
    }

} 

}

出现了这样的问题~~实在不知道怎么解决了~~求帮助

出现了什么问题？ 把问题描述一下

一点注册显示正在注册 然后就退出界面了 stop了

我看有个空指针异常呢 jsonParser.makeHttpRequest 有返回值吗？

返回的 jsonData 有具体值还是null？打印一下