Android应用与可观测性

Question

我正在android工作室上开发一个简单的应用程序。我使用的是“应用程序”、“可观察的”等等。我犯了这样的错误：

java.lang.RuntimeException: Unable to start activity ComponentInfo{id.wdharmana.doahindu/id.wdharmana.doahindu.MainActivity}: java.lang.ClassCastException: android.app.Application cannot be cast to id.wdharmana.doahindu.app.DoaApplication

第二错误

Caused by: java.lang.ClassCastException: android.app.Application cannot be cast to id.wdharmana.doahindu.app.DoaApplication

第三错误

at id.wdharmana.doahindu.MainActivity.onCreate(MainActivity.java:52)

这是我的完整MainActivity.java：

package id.wdharmana.doahindu;
import android.app.Activity;
import android.app.Dialog;
import android.app.ProgressDialog;
import android.app.SearchManager;
import android.content.Context;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.SearchView;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemLongClickListener;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;




import id.wdharmana.doahindu.adapter.ListJudulAdapter;
import id.wdharmana.doahindu.app.DoaApplication;
import id.wdharmana.doahindu.data.DefaultData;
import id.wdharmana.doahindu.helper.DoaHelper;
import id.wdharmana.doahindu.model.DoaModel;
import id.wdharmana.doahindu.model.DoaObserver;

import java.util.ArrayList;
import java.util.Observable;
import java.util.Observer;

public class MainActivity extends AppCompatActivity  implements Observer {

    private ListView lvJudul;
    private ArrayList<DoaModel> listJudul;
    private DoaHelper doaHelper;
    public ListJudulAdapter listJudulAdapter;
    private DoaApplication application;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        lvJudul = (ListView)findViewById(R.id.lvListJudul);

        listJudul = new ArrayList<DoaModel>();
        application = (DoaApplication) getApplication();
        application.getDoaObserver().addObserver(this);

        doaHelper = new DoaHelper(MainActivity.this);
        doaHelper.open();

        listJudul = doaHelper.getAllData();

        if (listJudul.size()>0) {
            bindData();
        }else{
            insertDefaultData();
        }

        lvJudul.setOnItemClickListener(new AdapterView.OnItemClickListener() {

            public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
                                    long arg3) {
                showMeaningDialog(MainActivity.this, listJudul.get(arg2));
            }
        });

        lvJudul.setOnItemLongClickListener(new OnItemLongClickListener() {

            public boolean onItemLongClick(AdapterView<?> arg0, View arg1,
                                           int arg2, long arg3) {
                deleteDialog(listJudul.get(arg2).getId());
                return false;
            }
        });



    }

    private void insertDefaultData() {
        // TODO Auto-generated method stub
        new StoreDefaultData().execute();
    }

    public void update(Observable observable, Object o) {
        if (o.equals(DoaObserver.NEED_TO_REFRESH)){
            bindData();
        }
    }

    private class StoreDefaultData extends AsyncTask<Void, Void, Void>{

        ProgressDialog mProgressDialog;

        @Override
        protected void onPreExecute() {
            // TODO Auto-generated method stub
            super.onPreExecute();

            mProgressDialog = new ProgressDialog(MainActivity.this);
            mProgressDialog.setTitle(getString(R.string.notify_input_data));
            mProgressDialog.setMessage(getString(R.string.text_please_wait));
            mProgressDialog.show();
        }

        @Override
        protected Void doInBackground(Void... params) {
            // TODO Auto-generated method stub

            for (int i = 0; i < DefaultData.defaultData.length; i++) {
                doaHelper.insert(DoaModel.getDoaModel(DefaultData.defaultData[i][0],
                        DefaultData.defaultData[i][1]));
            }

            listJudul = doaHelper.getAllData();

            return null;
        }

        @Override
        protected void onPostExecute(Void result) {
            // TODO Auto-generated method stub
            super.onPostExecute(result);
            mProgressDialog.dismiss();
            listJudulAdapter = new ListJudulAdapter(MainActivity.this, listJudul);
            lvJudul.setAdapter(listJudulAdapter);
        }

    }

    @Override
    protected void onDestroy() {
        if (doaHelper != null){
            doaHelper.close();
        }
        super.onDestroy();
    }

    public static void showMeaningDialog(final Activity activity, final DoaModel item) {
        final Dialog dialog = new Dialog(activity, R.style.AppCompatAlertDialogStyle);
        dialog.setContentView(R.layout.dialog_konten);
        dialog.setCancelable(true);

        TextView txtKonten = (TextView)dialog.findViewById(R.id.txtMeaning);
        TextView txtJudul = (TextView)dialog.findViewById(R.id.txtWord);
        Button btnTutup = (Button)dialog.findViewById(R.id.btnTutup);
        Button btnEdit = (Button)dialog.findViewById(R.id.btnEdit);

        txtKonten.setText(item.getKonten());
        txtJudul.setText(item.getJudul());

        btnEdit.setOnClickListener(new OnClickListener() {

            public void onClick(View v) {
                // TODO Auto-generated method stub
                //FormInputUpdateActivity.toFormInputUpdate(activity, item);
                dialog.dismiss();
            }
        });

        btnTutup.setOnClickListener(new View.OnClickListener() {

            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                dialog.dismiss();
            }
        });

        dialog.show();

    }

    private void deleteDialog(final int id) {
        // TODO Auto-generated method stub
        final Dialog dialog = new Dialog(MainActivity.this, R.style.AppCompatAlertDialogStyle);
        dialog.setTitle("Hapus");
        //dialog.setContentView(R.layout.dialog_delete);
        dialog.setCancelable(true);

       // Button btnYes = (Button)dialog.findViewById(R.id.btnDeleteYes);
      //  Button btnCancel = (Button)dialog.findViewById(R.id.btnDeleteCancel);

       // btnYes.setOnClickListener(new OnClickListener() {

        //    public void onClick(View v) {
       //         // TODO Auto-generated method stub
       //         doaHelper.delete(id);
       //         dialog.dismiss();
       //         Toast.makeText(MainActivity.this, getString(R.string.text_success_delete), Toast.LENGTH_LONG).show();
       //         application.getDoaObserver().refresh();
       //     }
       // });

        //btnCancel.setOnClickListener(new View.OnClickListener() {

           // public void onClick(View arg0) {
                // TODO Auto-generated method stub
              //  dialog.dismiss();
           // }
        //});

        dialog.show();

    }

    public void bindData(){
        if (listJudul.size()>0) {
            listJudul.clear();
        }
        listJudul = doaHelper.getAllData();
        listJudulAdapter = new ListJudulAdapter(MainActivity.this, listJudul);
        lvJudul.setAdapter(listJudulAdapter);
        listJudulAdapter.notifyDataSetChanged();
    }

    @Override
    protected void onResume() {
        // TODO Auto-generated method stub
        super.onResume();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_activity_main, menu);
        SearchManager searchManager =
                (SearchManager) getSystemService(Context.SEARCH_SERVICE);
        SearchView searchView =
                (SearchView) menu.findItem(R.id.action_search).getActionView();
        searchView.setSearchableInfo(
                searchManager.getSearchableInfo(getComponentName()));
        return true;
    }


}

我是DoaApplication.java

package id.wdharmana.doahindu.app;

import android.app.Application;

import id.wdharmana.doahindu.model.DoaObserver;

/**
 * Created by WDHARMANA on 9/18/2015.
 */
public class DoaApplication  extends Application {
    DoaObserver doaObserver;
    @Override
    public void onCreate() {
        super.onCreate();
        doaObserver = new DoaObserver();
    }

    public DoaObserver getDoaObserver(){
        return doaObserver;
    }
}

生成时没有错误。如果你有什么建议，请告诉我。提前谢谢。

Answer 1

将DoaApplication放入您的清单中，在<application>节点中作为android:name="id.wdharmana.doahindu.app.DoaApplication"放入

Answer 2

请确保你的AndroidManifest.xml是这样的：

<application 
    android:name="id.wdharmana.doahindu.app.DoaApplication"
    ... >
        ...
</application>

我想你忘了把你的