Unable to start activity in android...?

Question

As i am new to android development i am struck up with a problem in my project. Code is..

for processing webservice code i am calling webinterface class from main.java file as follows.

Main.java

      @Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    setContentView(R.layout.main);
WebServiceInterface webinterface=   new WebServiceInterface();
submit.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            getuser = username.getText().toString();
            getpass = password.getText().toString();

            HashMap<String, Object> map =  new HashMap<String,Object>();
            map.put("username", getuser);
            map.put("password", getpass);
            webinterface.sendRequest(map);
        }
    });

In Webinterface class i am receiving the following map values & converting them to string & send to RestClient.class to process webservice request..

WebServiceInterface.java

    ArrayList<String> ast = new ArrayList<String>();
  Collection<Object> strings = map.values();
    Iterator iterator = strings.iterator();
    while (iterator.hasNext()) {
        getuser = (String) iterator.next();
        ast.add(getuser);
    }

    String password = ast.get(0).toString();
    String username = ast.get(1).toString();

    RestClient client = new RestClient(
            "***********************");
    client.AddParam("username", username);
    client.AddParam("password", password);

    try {
        client.Execute(RequestMethod.POST);
    } catch (Exception e) {
        e.printStackTrace();
    }

      String response = client.getResponse();

     /** here getting response & sending that response back to Main.java class**/

       Main main = new Main();
   main.responseData(responsedata);

here after receiving response method from interface class the following process is going on in Main.java class

Main.java

     @Override
public void onCreate(Bundle savedInstanceState) {

      System.out.println("response is----^^^^^^^^^^====>>>>>>    " + getrespstatus + "_______---->>   > " + respdoctorID);
       }//end of oncreate...

  public void responseData(HashMap<String, Object> responsedata) {
    // TODO Auto-generated method stub

    System.out.println("response data in main class->>>>>>>>  "  + responsedata);

    Collection<Object> strings = responsedata.values();
    Iterator iterator = strings.iterator();
    while (iterator.hasNext()) {
        getresponse = (String) iterator.next();
        ast.add(getresponse);
    }

    String status = ast.get(0).toString();

    try {
        JSONObject json = new JSONObject(status);
        getrespstatus = json.getString("status");
        respdoctorID = json.getString("doctorID");
        callmethod(getrespstatus, respdoctorID);
        System.out.println("response is----^^^^^^^^^^====>>>>>>    " + getrespstatus + "_______---->>   > " + respdoctorID);
                /* if(getrespstatus == "true")
                  {
                   startActivity(new Intent(Main.this,Second.class)) 
                  }else 
                  {
                    //some alert message
                   }*/
    } catch (JSONException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

here if response status== true, i want to start activity. but here i am getting error as null pointer exception.. And my other doubt is here i am getting response & doctorID. if i am trying to access the following values in oncreate method, it showing as null values (simply to say if i am printing response values in log, in responseData method i am getting, if printing from oncreate getting null values) So, can anyone help me with this...

Your code seems vague. You need to understand about the `Activity` and its life cycle. — Paresh Mayani, Oct 23 '12 at 10:32
And you dont need to do this: `Main main = new Main();`. I mean no need to implement method like sending and receiving response as such. — Paresh Mayani, Oct 23 '12 at 10:32

score 2 · Answer 1 · answered Oct 23 '12 at 10:35

2

You have to call super in onCreate. I strongly recommend reading this article about Activity lifecycle.

As for returning the response, the simplest way would be to add your Main instance to the WebInterface class as a reference, maybe in constructor.

answered Oct 23 '12 at 10:35

molnarm

9,856
2
42
60

Thanks for you answer.. can you provide any example related to my code..... – code_finder Oct 23 '12 at 10:37
1

Add this line to onCreate(): super.onCreate(savedInstanceState); – molnarm Oct 23 '12 at 10:39
@MártonMolnár, I think he hasnt post all his code. where is the setcontview() – Lazy Ninja Oct 23 '12 at 10:40
i already added the following line – Oct 23 '12 at 10:59

Unable to start activity in android...?

1 Answers1