Question

由于我是Android开发的新手，我在项目中遇到了问题。代码是......

用于处理webservice代码我从main.java文件调用webinterface类，如下所示。

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);
        }
    });

在Webinterface类中，我收到以下地图值＆amp;将它们转换为字符串＆amp;发送到RestClient.class以处理webservice请求..

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);

这里接收到来自接口类的响应方法后，Main.java类中继续进行以下过程

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();
    }
}

如果响应状态== true，我想开始活动。但在这里我得到错误作为空指针异常.. 而我的另一个疑问是在这里我得到了回应＆amp; doctorID。如果我试图在oncreate方法中访问以下值，它显示为空值（简单地说，如果我在日志中打印响应值，在响应数据方法中我得到，如果从oncreate打印获取空值）那么，任何人都可以帮助我...

Answer 1

您必须在super中致电onCreate。我强烈建议您阅读有关活动生命周期的this article。

至于返回响应，最简单的方法是将Main实例添加到WebInterface类作为引用，可能在构造函数中。

无法在Android中启动活动......？

1 个答案: