从listview中的sqlite数据库中获取数据，该数据库放在一个片段中

Question

在我的应用程序中，我使用了两个片段，其中第一个片段用于在listview中显示sqlite数据库中的数据。那么，我该怎么办？

这是我的主要活动，名为CategoryList.java

package com.my.quote;

public class CategoryList extends ActionBarActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);


if(savedInstanceState == null){

    getSupportFragmentManager().beginTransaction().add(R.id.menuContainer, new    MenuFrag()).commit();         
}   
}   

}

下面是菜单片段，其中包含两个按钮。单击第一个按钮时，类别片段将获得下面的代码，我已经开始了：

package com.my.quote;

public class CatFragActivity extends Fragment {

private QuoteHelper dbQuoteHelper = null;
private Cursor ourcursor = null;
private QuoteAdapter adapter = null;
public int a = 0;

public CatFragActivity(){

}
 public View onCreateView(LayoutInflater inflater,
        @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {


     View rootview = inflater.inflate(R.layout.cat_frag, container, false);


     ListView mylistview  = (ListView)getActivity().findViewById(R.id.CatList);
        dbQuoteHelper = new QuoteHelper(getActivity());
        dbQuoteHelper.createDatabase();
        dbQuoteHelper.openDataBase();
        ourcursor = dbQuoteHelper.getcursor(a);   
        adapter = new QuoteAdapter(ourcursor);
        mylistview.setAdapter(adapter);
        mylistview.setOnItemClickListener(new OnItemClickListener() {

            public void onItemClick(AdapterView<?> mylistview, View v, int position,
                    long id) {
                     Intent i = new Intent("com.my.quote.QuoteActivity");
                        Bundle b = new Bundle();
                        b.putInt("id", (int) id);
                         i.putExtras(b);
                         startActivity(i);
            }
        });
    return rootview;
}

  class QuoteAdapter extends CursorAdapter{
    QuoteAdapter(Cursor c){
        super(getActivity(),c);
    }

    @Override
    public void bindView(View row, Context ctxt, Cursor c) {
        QuoteHolder holder = (QuoteHolder)row.getTag();
        holder.populateFrom(c,dbQuoteHelper);
    }

    @Override
    public View newView(Context ctxt, Cursor c, ViewGroup parent) {
        LayoutInflater inflater = getLayoutInflater();
        View row = inflater.inflate(R.layout.row, parent, false);
        QuoteHolder holder = new QuoteHolder(row);
        row.setTag(holder);
        return(row);
    }
}

 class QuoteHolder{
        private TextView name = null;

        QuoteHolder(View row){
            name=(TextView)row.findViewById(R.id.quoteText);
        }
        void populateFrom(Cursor c, QuoteHelper r){
            name.setText(r.getName(c));
        }
    }
}

数据库助手类如下：

package com.my.quote;
public class QuoteHelper extends SQLiteOpenHelper{
private static final String DATABASE_PATH="/data/data/com.my.quote/databases/";
private static final String DATABASE_NAME="store.db";
private static final int SCHEMA_VERSION=1;
private static final String TABLE_NAME="quotes";
private static final String TABLE_NAME_CAT="categories";
private static final String COLUMN_ID="_id";
private static final String COLUMN_TITLE="body";
private static final String COLUMN_CAT="name";
public static int i;
//private static final String COLUMN_CAT="4";

public SQLiteDatabase dbsqlite;
private final Context mycontext;

public QuoteHelper(Context context) {
    super(context,DATABASE_NAME,null,SCHEMA_VERSION );
    this.mycontext=context;
}

@Override
public void onCreate(SQLiteDatabase db) {

}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}

public void createDatabase(){
    createDB();
}

private void createDB(){
    boolean dbExist = DBExists();
    if(!dbExist){
        this.getReadableDatabase();
        copyDBFromResources();
    }
}


private boolean DBExists() {
    SQLiteDatabase db = null;

    try{
        String databasePath = DATABASE_PATH + DATABASE_NAME;
        db = SQLiteDatabase.openDatabase(databasePath, null, 
                SQLiteDatabase.OPEN_READWRITE);
        db.setLocale(Locale.getDefault());
        db.setLockingEnabled(true);
        db.setVersion(1);
    }catch(SQLiteException e){
        Log.e("SqlHelper","database not found");
    }

    if(db != null){
        db.close();
    }
    return db != null ? true : false;
}

private void copyDBFromResources() {
    InputStream inputStream = null;
    OutputStream outputStream = null;
    String dbFilePath = DATABASE_PATH + DATABASE_NAME;

    try{
        inputStream = mycontext.getAssets().open(DATABASE_NAME);
        outputStream = new FileOutputStream(dbFilePath);
        byte[] buffer = new byte[1024];
        int length;
        while((length = inputStream.read(buffer))> 0){
            outputStream.write(buffer,0,length);
        }
        outputStream.flush();
        outputStream.close();
        inputStream.close();

    }catch(IOException e){
        throw new Error("problem copying databse");
    }
}

public void openDataBase() throws SQLException{
    String mypath = DATABASE_PATH+DATABASE_NAME;
    dbsqlite = SQLiteDatabase.openDatabase(mypath, null,
            SQLiteDatabase.OPEN_READWRITE);
}

@Override
public synchronized void close(){
    if(dbsqlite != null){
        dbsqlite.close();
    }
    super.close();
}


public Cursor getcursor(int a){
    if(a==0){
        SQLiteQueryBuilder querybuilder = new SQLiteQueryBuilder();
        querybuilder.setTables(TABLE_NAME_CAT);

        String[] asCloumsToReturn = new String[] {COLUMN_ID,COLUMN_CAT};

        Cursor mcursor = querybuilder.query(dbsqlite, asCloumsToReturn, null, null,   null, null, null);
        return mcursor;
            }
    else{

        int i = a;
        SQLiteQueryBuilder querybuilder = new SQLiteQueryBuilder();
        querybuilder.setTables(TABLE_NAME);

        String[] asCloumsToReturn = new String[] {COLUMN_ID,COLUMN_TITLE};
        String column ="category_id ="+ i;


        Cursor mcursor = querybuilder.query(dbsqlite, asCloumsToReturn, column, null, null, null, null);
        return mcursor;
    }

}

public String getName(Cursor c){
    return(c.getString(1));
}

  public Cursor getDetailByTerm(String id) {
        String[] args={id};

        return(getReadableDatabase()
                .rawQuery("SELECT _id, body FROM quotes WHERE _id=?",
                        args));
    }

  public Cursor getDetailsByCategory(String id){
      String[] args={id};
      return(getReadableDatabase()
              .rawQuery("SELECT _id, body from quotes WHERE category_id = ?", args)
              );

  }

}