Hi all, I make a content provider named 'DictionaryProvider' (Based on NotepadProvider). When my program run to command 'qb.query(db, projection, selection, selectionArgs, null, null, orderBy);', error happen. I don't know how to fix. please help me. Below is my code

// file main calling DictionnaryProvider
    @Override
    public void onCreate(Bundle savedInstanceState) {       
        super.onCreate(savedInstanceState);
        setContentView(R.layout.dictionary);
        final String[] PROJECTION = new String[] {
            DicColumns._ID, // 0
            DicColumns.KEY_WORD, // 1
            DicColumns.KEY_DEFINITION // 2
        };
        Cursor c = managedQuery(DicColumns.CONTENT_URI, PROJECTION, null, null, DicColumns.DEFAULT_SORT_ORDER);
        String str = "";
        if (c.moveToFirst()) {
            int wordColumn = c.getColumnIndex("KEY_WORD");
            int defColumn = c.getColumnIndex("KEY_DEFINITION");
            do {
                // Get the field values
                str = "";
                str += c.getString(wordColumn);
                str +="\n";
                str +=c.getString(defColumn);
            } while (c.moveToNext());
        }                
        Toast.makeText(this, str, Toast.LENGTH_SHORT).show();
}
// file DictionaryProvider.java
package com.example.helloandroid;

import java.util.HashMap;
import android.content.ContentProvider;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteQueryBuilder;
import android.net.Uri;
import android.text.TextUtils;
import com.example.helloandroid.Dictionary.DicColumns;

public class DictionaryProvider extends ContentProvider {

    //private static final String TAG = "DictionaryProvider";
    private DictionaryOpenHelper dbdic;
    static final int DATABASE_VERSION = 1;  
    static final String DICTIONARY_DATABASE_NAME = "dictionarydb";
    static final String DICTIONARY_TABLE_NAME = "dictionary";
    private static final UriMatcher sUriMatcher;
    private static HashMap<String, String> sDicProjectionMap;

    @Override
    public int delete(Uri arg0, String arg1, String[] arg2) {
        // TODO Auto-generated method stub
        return 0;
    }

    @Override
    public String getType(Uri arg0) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public Uri insert(Uri arg0, ContentValues arg1) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public boolean onCreate() {
        // TODO Auto-generated method stub
        dbdic = new DictionaryOpenHelper(getContext(), DICTIONARY_DATABASE_NAME, null, DATABASE_VERSION);
        return true;
    }

    @Override
    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {

        SQLiteQueryBuilder qb = new SQLiteQueryBuilder();
        qb.setTables(DICTIONARY_TABLE_NAME);

        switch (sUriMatcher.match(uri)) {
        case 1:
            qb.setProjectionMap(sDicProjectionMap);
            break;
        case 2:
            qb.setProjectionMap(sDicProjectionMap);
            qb.appendWhere(DicColumns._ID + "=" + uri.getPathSegments().get(1));
            break;

        default:
            throw new IllegalArgumentException("Unknown URI " + uri);
        }

        // If no sort order is specified use the default
        String orderBy;
        if (TextUtils.isEmpty(sortOrder)) {
            orderBy = DicColumns.DEFAULT_SORT_ORDER;
        } else {
            orderBy = sortOrder;
        }

        // Get the database and run the query
        SQLiteDatabase db = dbdic.getReadableDatabase();
        Cursor c = qb.query(db, projection, selection, selectionArgs, null, null, orderBy);

        // Tell the cursor what uri to watch, so it knows when its source data changes
        c.setNotificationUri(getContext().getContentResolver(), uri);
        return c;       
    }

    @Override
    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
        // TODO Auto-generated method stub
        return 0;
    }

    static {
        sUriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
        sUriMatcher.addURI(Dictionary.AUTHORITY, "dictionary", 1);
        sUriMatcher.addURI(Dictionary.AUTHORITY, "dictionary/#", 2);        

        sDicProjectionMap = new HashMap<String, String>();
        sDicProjectionMap.put(DicColumns._ID, DicColumns._ID);
        sDicProjectionMap.put(DicColumns.KEY_WORD, DicColumns.KEY_WORD);
        sDicProjectionMap.put(DicColumns.KEY_DEFINITION, DicColumns.KEY_DEFINITION);

        // Support for Live Folders.
        /*sLiveFolderProjectionMap = new HashMap<String, String>();
        sLiveFolderProjectionMap.put(LiveFolders._ID, NoteColumns._ID + " AS " +
                LiveFolders._ID);
        sLiveFolderProjectionMap.put(LiveFolders.NAME, NoteColumns.TITLE + " AS " +
                LiveFolders.NAME);*/
        // Add more columns here for more robust Live Folders.
    }
}

// file Dictionary.java
package com.example.helloandroid;

import android.net.Uri;
import android.provider.BaseColumns;

/**
 * Convenience definitions for DictionaryProvider
 */
public final class Dictionary {
    public static final String AUTHORITY = "com.example.helloandroid.provider.Dictionary";

    // This class cannot be instantiated
    private Dictionary() {}

    /**
     * Dictionary table
     */
    public static final class DicColumns implements BaseColumns {
        // This class cannot be instantiated
        private DicColumns() {}

        /**
         * The content:// style URL for this table
         */
        public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY + "/dictionary");

        /**
         * The MIME type of {@link #CONTENT_URI} providing a directory of notes.
         */
        //public static final String CONTENT_TYPE = "vnd.android.cursor.dir/vnd.google.note";

        /**
         * The MIME type of a {@link #CONTENT_URI} sub-directory of a single note.
         */
        //public static final String CONTENT_ITEM_TYPE = "vnd.android.cursor.item/vnd.google.note";

        /**
         * The default sort order for this table
         */
        public static final String DEFAULT_SORT_ORDER = "modified DESC";

        /**
         * The key_word of the dictionary
         * <P>Type: TEXT</P>
         */
        public static final String KEY_WORD = "KEY_WORD";

        /**
         * The key_definition of word
         * <P>Type: TEXT</P>
         */
        public static final String KEY_DEFINITION = "KEY_DEFINITION";               
    }
}

thanks so much