Android应用中的java.lang.ClassNotFoundException。

Question

这是我的Manifest.xml：

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
    package="com.example.testcode" 
    android:versionCode="1" 
    android:versionName="1.0" > 


    <uses-permission android:name="android.permission.READ_CONTACTS"/> 
    <uses-sdk android:minSdkVersion="15" /> 

    <application 

     android:icon="@drawable/ic_launcher" 
     android:label="@string/app_name" > 

      <activity android:label="@string/app_name" android:name=".TestAndActivity"> 
      <intent-filter> 
       <action android:name="android.intent.action.MAIN" /> 

       <category android:name="android.intent.category.LAUNCHER" /> 
      </intent-filter> 
     </activity> 
     </application> 

</manifest> 

这是我的课：

package com.example.testcode; 

import android.app.ListFragment; 
import android.app.LoaderManager; 
import android.content.CursorLoader; 
import android.content.Loader; 
import android.database.Cursor; 
import android.net.Uri; 
import android.os.Bundle; 
import android.provider.ContactsContract; 
import android.support.v4.widget.SimpleCursorAdapter; 
import android.text.TextUtils; 
import android.util.Log; 
import android.view.Menu; 
import android.view.MenuInflater; 
import android.view.MenuItem; 
import android.view.View; 
import android.widget.ListView; 
import android.widget.SearchView; 
import android.widget.SearchView.OnQueryTextListener; 

public class TestAndActivity extends ListFragment 
     implements OnQueryTextListener, LoaderManager.LoaderCallbacks<Cursor> { 

    // This is the Adapter being used to display the list's data. 
    SimpleCursorAdapter mAdapter; 

    // If non-null, this is the current filter the user has provided. 
    String mCurFilter; 

    @Override 
    public void onActivityCreated(Bundle savedInstanceState) { 
     super.onActivityCreated(savedInstanceState); 

     // Give some text to display if there is no data. In a real 
     // application this would come from a resource. 
     setEmptyText("No phone numbers"); 

     // We have a menu item to show in action bar. 
     setHasOptionsMenu(true); 

     // Create an empty adapter we will use to display the loaded data. 
     mAdapter = new SimpleCursorAdapter(getActivity(), 
       android.R.layout.simple_list_item_2, null, 
       new String[] { ContactsContract.Contacts.DISPLAY_NAME, ContactsContract.Contacts.CONTACT_STATUS }, 
       new int[] { android.R.id.text1, android.R.id.text2 }, 0); 
     setListAdapter(mAdapter); 

     // Start out with a progress indicator. 
     setListShown(false); 

     // Prepare the loader. Either re-connect with an existing one, 
     // or start a new one. 
     getLoaderManager().initLoader(0, null, this); 
    } 

    @Override public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) { 
     // Place an action bar item for searching. 
     MenuItem item = menu.add("Search"); 
     item.setIcon(android.R.drawable.ic_menu_search); 
     item.setShowAsAction(MenuItem.SHOW_AS_ACTION_IF_ROOM); 
     SearchView sv = new SearchView(getActivity()); 
     sv.setOnQueryTextListener(this); 
     item.setActionView(sv); 
    } 

    public boolean onQueryTextChange(String newText) { 
     // Called when the action bar search text has changed. Update 
     // the search filter, and restart the loader to do a new query 
     // with this filter. 
     mCurFilter = !TextUtils.isEmpty(newText) ? newText : null; 
     getLoaderManager().restartLoader(0, null, this); 
     return true; 
    } 

    @Override public boolean onQueryTextSubmit(String query) { 
     // Don't care about this. 
     return true; 
    } 

    @Override public void onListItemClick(ListView l, View v, int position, long id) { 
     // Insert desired behavior here. 

     Log.i("FragmentComplexList", "Item clicked: " + id); 
    } 

    // These are the Contacts rows that we will retrieve. 
    static final String[] CONTACTS_SUMMARY_PROJECTION = new String[] { 
     ContactsContract.Contacts._ID, 
     ContactsContract.Contacts.DISPLAY_NAME, 
     ContactsContract.Contacts.CONTACT_STATUS, 
     ContactsContract.Contacts.CONTACT_PRESENCE, 
     ContactsContract.Contacts.PHOTO_ID, 
     ContactsContract.Contacts.LOOKUP_KEY, 
    }; 

    public Loader<Cursor> onCreateLoader(int id, Bundle args) { 
     // This is called when a new Loader needs to be created. This 
     // sample only has one Loader, so we don't care about the ID. 
     // First, pick the base URI to use depending on whether we are 
     // currently filtering. 
     Uri baseUri; 
     if (mCurFilter != null) { 
      baseUri = Uri.withAppendedPath(ContactsContract.Contacts.CONTENT_FILTER_URI, 
        Uri.encode(mCurFilter)); 
     } else { 
      baseUri = ContactsContract.Contacts.CONTENT_URI; 
     } 

     // Now create and return a CursorLoader that will take care of 
     // creating a Cursor for the data being displayed. 
     String select = "((" + ContactsContract.Contacts.DISPLAY_NAME + " NOTNULL) AND (" 
       + ContactsContract.Contacts.HAS_PHONE_NUMBER + "=1) AND (" 
       + ContactsContract.Contacts.DISPLAY_NAME + " != ''))"; 
     return new CursorLoader(getActivity(), baseUri, 
       CONTACTS_SUMMARY_PROJECTION, select, null, 
       ContactsContract.Contacts.DISPLAY_NAME + " COLLATE LOCALIZED ASC"); 
    } 

    public void onLoadFinished(Loader<Cursor> loader, Cursor data) { 
     // Swap the new cursor in. (The framework will take care of closing the 
     // old cursor once we return.) 
     mAdapter.swapCursor(data); 

     // The list should now be shown. 
     if (isResumed()) { 
      setListShown(true); 
     } else { 
      setListShownNoAnimation(true); 
     } 
    } 

    public void onLoaderReset(Loader<Cursor> loader) { 
     // This is called when the last Cursor provided to onLoadFinished() 
     // above is about to be closed. We need to make sure we are no 
     // longer using it. 
     mAdapter.swapCursor(null); 
    } 
} 

这是Android的一个基本的实现装载机后者从手机联系人，并显示它们。 错误：

Caused by: java.lang.ClassCastException: com.example.testcode.TestAndActivity cannot be cast to android.app.Activity 

Answer 1

打嗝，你得到，因为你正试图设置应用程序启动活动的片段异常（即TestAndActivity不是一个活动，延续ListFragmant）：

<activity android:label="@string/app_name" android:name=".TestAndActivity"> 

使用fragmanents时，它们必须存在于Activity中。阅读the Android Development page here with regard to Fragments。基本上，为了解决这个问题，你需要创建一个正常的活动来启动，然后将Fragment放入活动中。

的具体部分，你需要阅读的开发商是Adding a fragment to an activity