在android中实现适配器类的接口

Question

我试图从扩展BaseAdapter的适配器类中调用一个webservice。我想在这个适配器类中实现接口类。但是当我运行应用程序时，它会抛出ClassCastException。:-

com.mahi.interfaces.AsyncInterface java.lang.ClassCastException:不能将com.mahi.MainActivity转换为com.mahi.MainActivity

这是我的密码:-

public class NewLibsAdapter extends PagerAdapter implements AsyncInterface {

    public NewLibsAdapter(Context context, Fragment fragment, int positionNo) {

        this.context = context;
        inflater = (LayoutInflater) this.context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        this.positionNo = positionNo;

        userId = AppMethod.getIntegerPreference(context, AppConstant.ID);

        SoapObject request = new SoapObject(AppConstant.NAMESPACE, AppConstant.METHOD_NAME_GET_USER_LIBRARY);

        request.addProperty("uid", userId);
        request.addProperty("reccount", recCount);

        DotNetWS logInWS = new DotNetWS(context, request, AppConstant.METHOD_NAME_GET_USER_LIBRARY, AppConstant.GetUserLibraryWS);
        logInWS.execute();

    }

    // This is my interface override method
    @Override
    public void onWSResponse(String json, String WSType) {
        Log.e(TAG, json);
    }

}

这是我的DotNetWS课程:-

public class DotNetWS extends AsyncTask<String, String, String> {

    Context context;
    SoapObject request;
    AsyncInterface asyncInterface;
    String action;
    String wsType;

    ProgressDialog pDialog;

    public DotNetWS(Context context, SoapObject request, String action, String wsType) {
        this.context = context;
        this.request = request;
        this.action = action;
        this.wsType = wsType;
        this.asyncInterface = (AsyncInterface) context;
    }

    public DotNetWS(Context context, Fragment fragment, SoapObject request, String action, String wsType) {
        this.context = context;
        this.request = request;
        this.action = action;
        this.wsType = wsType;
        this.asyncInterface = (AsyncInterface) fragment;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();

        pDialog = new ProgressDialog(context);
        pDialog.setTitle("Connecting...");
        pDialog.setMessage("Please Wait...");
        pDialog.setCancelable(false);
        pDialog.show();

    }

    @Override
    protected String doInBackground(String... params) {

        // Coding
    }

    @Override
    protected void onPostExecute(String s) {
        super.onPostExecute(s);
        pDialog.dismiss();
        asyncInterface.onWSResponse(s, wsType);
    }

}

对这种错误有什么解决办法吗？我可以在适配器类中实现接口类吗？请帮帮忙。谢谢。

Answer 1

试试这个，在适配器内部：

 DotNetWS logInWS = new DotNetWS(this, request,                   
 AppConstant.METHOD_NAME_GET_USER_LIBRARY, AppConstant.GetUserLibraryWS);
    logInWS.execute();

您正在发送类似于参数的上下文，但是您的上下文是MainActivity，您必须发送您的适配器类(这个，或NewLibsAdapter.this)。

祝好运!

Answer 2

您有两个DotNetWS构造函数，并且正在调用DotNetWS构造函数

DotNetWS logInWS = new DotNetWS(context, request, AppConstant.METHOD_NAME_GET_USER_LIBRARY, AppConstant.GetUserLibraryWS);

它将上下文转换为AsyncInterface。真的吗？

this.asyncInterface = (AsyncInterface) context;

根据错误文本，此上下文不实现AsyncInterface。