android - LoaderManager 未初始化... getLoaderManager().initLoader 的问题

Question

我知道有很多这样的常见问题，但我似乎找不到解决方案。当我尝试使用 getLoaderManager().initLoader(LOADER_ID, null, this); 初始化加载程序时，错误 The method initLoader(int, Bundle, LoaderManager.LoaderCallbacks) in the type LoaderManager is not applicable for参数 (int, null, Gridview) 出现了。

这让我相信程序没有识别出 Gridview 实现了加载器管理器。我不确定这是为什么以及从这里去哪里。我尝试使用不同的进口产品，但这没有用。我还确保我有正确的下载来支持装载机。我正在使用的代码如下。

package com.example.camerapreview;

import android.support.v4.app.LoaderManager;
import android.support.v4.app.LoaderManager.LoaderCallbacks;
import android.support.v4.content.CursorLoader;
import android.support.v4.content.Loader;
import android.support.v4.widget.CursorAdapter;

//Omissis imports


public class Gridview extends Activity implements LoaderManager.LoaderCallbacks<Cursor>{       
    private static final String TAG = "Checking Database";
    private static final String TAG1 = "Checking Thumbnail";

    Cursor cursor;
    int columnindexid;
    int columnindexdata;
    int videoidindex;
    int videopathindex;
    GridviewData entry;
    GridView gridview;
    VideoAdapter videoadapter;
    Cursor curs;

    ImageLoaderConfiguration config;

    String[] mediaColumns = {
        MediaStore.Video.Media._ID,
        MediaStore.Video.Media.DATA,
        MediaStore.Video.Media.TITLE,
        MediaStore.Video.Media.MIME_TYPE
    };

    private static final int LOADER_ID = 1;
    int flags = 0;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.preview);
        gridview = (GridView) this.findViewById(R.id.gridview);


        cursor = getContentResolver().query(MediaStore.Video.Media.EXTERNAL_CONTENT_URI, mediaColumns, null, null, null);
        columnindexid = cursor.getColumnIndexOrThrow(MediaStore.Video.Media._ID);
        columnindexdata = cursor.getColumnIndexOrThrow(MediaStore.Video.Media.DATA);

        entry = new GridviewData(this);
        entry.open();

        getLoaderManager().initLoader(LOADER_ID, null, this);
        DataEntry putitin = new DataEntry(entry, this);
        putitin.execute();

        //the cursor used in the cursor adapater
        curs = entry.adapterCursor();
        videoidindex = entry.Indexfinder(curs);
        videopathindex = entry.Indexfinder2(curs);

        config = new ImageLoaderConfiguration.Builder(this)
                        .imageDownloader(new BaseImageDownloader(this))
                        .build();

        ImageLoader.getInstance().init(config);
        Log.i(TAG, "Before set adapater");
        gridview.setAdapter(new VideoAdapter(this, curs, flags));
     }
}

编辑:

@Override
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
    String[] projection = { GridviewData.VIDEOID, GridviewData.VIDEOFILEPATH };
    return new CursorLoader(Gridview.this, MyContentProvider.CONTENT_URI, projection, null, null, null);
}

@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor c) {
    cursoradapter.swapCursor(c);
}

@Override
public void onLoaderReset(Loader<Cursor> loader) {
    cursoradapter.swapCursor(null);     
}

Answer 1

错误是由您的导入引起的:

import android.support.v4.app.LoaderManager;
import android.support.v4.app.LoaderManager.LoaderCallbacks;
import android.support.v4.content.CursorLoader;
import android.support.v4.content.Loader;
import android.support.v4.widget.CursorAdapter;

它们适用于 FragmentActivity 但您使用的是普通 Activity 所以它们应该是:

import android.app.LoaderManager;
import android.app.LoaderManager.LoaderCallbacks;
import android.content.CursorLoader;
import android.content.Loader;
import android.widget.CursorAdapter;

请注意，在这种情况下，您的 android:minSdkVersion 应该是 11。如果您需要与较低版本兼容，只需保持导入原样并使用 FragmentActivity。