如何使用Loader填充ListView？

时间：2016-09-25 16:34:40

标签： android listview android-studio

我正在Developer site中测试Listview示例，这是使用Loader和Adapter填充ListView的示例。该应用程序失败，因为一些未知的错误。我不确定但是怀疑陈述getLoaderManager().initLoader(0, null, this );有问题。

模拟器显示＆＃34;不幸的是，ListViewLoader已停止。＆＃34; 我在<uses-permission android:name="android.permission.READ_CONTACTS" />标记之前也使用<application>，但收到了同样的错误。在清单文件中。 logcat显示以下消息：

    09-25 22:57:33.853 28524-28618/com.example.listviewloader E/AndroidRuntime: FATAL EXCEPTION: AsyncTask #1
Process: com.example.listviewloader, PID: 28524
java.lang.RuntimeException: An error occurred while executing doInBackground()
at android.os.AsyncTask$3.done(AsyncTask.java:309)
at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:354)
at java.util.concurrent.FutureTask.setException(FutureTask.java:223)
at java.util.concurrent.FutureTask.run(FutureTask.java:242)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at java.lang.Thread.run(Thread.java:818)
Caused by: java.lang.SecurityException: Permission Denial: opening provider com.android.providers.contacts.ContactsProvider2 from ProcessRecord{3c98c11 28524:com.example.listviewloader/u0a108} (pid=28524, uid=10108) requires android.permission.READ_CONTACTS or android.permission.WRITE_CONTACTS
at android.os.Parcel.readException(Parcel.java:1599)
at android.os.Parcel.readException(Parcel.java:1552)
at android.app.ActivityManagerProxy.getContentProvider(ActivityManagerNative.java:3550)
at android.app.ActivityThread.acquireProvider(ActivityThread.java:4778)
at android.app.ContextImpl$ApplicationContentResolver.acquireUnstableProvider(ContextImpl.java:2018)
at android.content.ContentResolver.acquireUnstableProvider(ContentResolver.java:1468)
at android.content.ContentResolver.query(ContentResolver.java:475)
at android.content.CursorLoader.loadInBackground(CursorLoader.java:64)
at android.content.CursorLoader.loadInBackground(CursorLoader.java:56)
     at android.content.AsyncTaskLoader.onLoadInBackground(AsyncTaskLoader.java:312)
     at android.content.AsyncTaskLoader$LoadTask.doInBackground(AsyncTaskLoader.java:69)
     at android.content.AsyncTaskLoader$LoadTask.doInBackground(AsyncTaskLoader.java:66)
     at android.os.AsyncTask$2.call(AsyncTask.java:295)
     at java.util.concurrent.FutureTask.run(FutureTask.java:237)
     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113) 
     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588) 
     at java.lang.Thread.run(Thread.java:818)    09-25 22:57:33.859 28524-28621/com.example.listviewloader D/OpenGLRenderer: Use 
EGL_SWAP_BEHAVIOR_PRESERVED: true
09-25 22:57:33.863 28524:28524 D/  ]
HostConnection::get() New Host Connection established 0xaa9e84a0, tid 28524
    09-25 22:57:34.200 28524-28621/com.example.listviewloader I/OpenGLRenderer: Initialized EGL, version 1.4
    09-25 22:57:34.910 28524-28621/com.example.listviewloader E/Surface: getSlotFromBufferLocked: unknown buffer: 0xb40943e0

提前感谢您在以下代码中发现任何问题。

import android.app.ListActivity;
import android.content.CursorLoader;
import android.database.Cursor;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.support.v4.widget.DrawerLayout;
import android.util.Log;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListView;
import android.widget.ProgressBar;
import android.app.LoaderManager;
import android.content.Loader;
import android.widget.SimpleCursorAdapter;
import android.widget.Toast;    

public class MainActivity extends ListActivity
    implements LoaderManager.LoaderCallbacks<Cursor> {

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

// These are the Contacts rows that we will retrieve
static final String[] PROJECTION = new String[] {ContactsContract.Data._ID,
        ContactsContract.Data.DISPLAY_NAME};

// This is the select criteria
static final String SELECTION = "((" +
        ContactsContract.Data.DISPLAY_NAME + " NOTNULL) AND (" +
        ContactsContract.Data.DISPLAY_NAME + " != '' ))";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);    

    // For the cursor adapter, specify which columns go into which views
    String[] fromColumns = {ContactsContract.Data.DISPLAY_NAME};
    int[] toViews = {android.R.id.text1}; // The TextView in simple_list_item_1

    // Create an empty adapter we will use to display the loaded data.
    // We pass null for the cursor, then update it in onLoadFinished()
    mAdapter = new SimpleCursorAdapter(this,
            android.R.layout.simple_list_item_1, null,
            fromColumns, toViews, 0);
    setListAdapter(mAdapter);

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

// Called when a new Loader needs to be created
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
    // Now create and return a CursorLoader that will take care of
    // creating a Cursor for the data being displayed.

    return new CursorLoader(this, ContactsContract.Data.CONTENT_URI,
            PROJECTION, SELECTION, null, null);
}

// Called when a previously created loader has finished loading
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);
}

// Called when a previously created loader is reset, making the data unavailable
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);
}

@Override
public void onListItemClick(ListView l, View v, int position, long id) {
    // Do something when a list item is clicked
}

2 个答案:

答案 0 :(得分：0)

SecurityException和权限拒绝提供了可能的原因 - 您是否已授予您的应用程序访问权限以读取（并可能写入）您的联系人？

您需要的许可是：

Read access to one or more tables
<uses-permission android:name="android.permission.READ_CONTACTS">.
Write access to one or more tables
<uses-permission android:name="android.permission.WRITE_CONTACTS">.

答案 1 :(得分：0)

  

引起：java.lang.SecurityException：Permission Denial：打开提供者   com.android.providers.contacts.ContactsProvider

如果您在Android 6或hiegher上运行您的应用，请确保您的应用中所需的所有权限都是example

相关问题
最新问题