Android 无法更新源（SQLiteOpenHelper）

我是DB的新手。我开发了一个应用程序，它可以获取最新的20个提要（JSON数据），并显示在定制的ListView中。 我还成功地将提要插入到DB中。但当我第二次加载应用程序时，数据库并没有更新，而是插入了两次提要。这里我的问题是如何更新现有提要？。如果可能的话，给我举个例子。 FragmentFeed.java

public class FragmentFeeds extends Fragment {

private static String url = "http://agile-tor-8294.herokuapp.com/home/publishedJson";
// JSON Node names
static final String TAG_BODY = "body";
static final String TAG_CREATED_AT = "created_at";
static final String TAG_DATE_TIME = "date_time";
static final String TAG_DEPARTEMENT = "department";
static final String TAG_ID = "id";
static final String TAG_INCLUDE = "include";
static final String TAG_MEDI_TYPE = "mediaType";
static final String TAG_PRIORITY = "priority";
static final String TAG_TITLE = "title";
static final String TAG_UPDATED_AT = "updated_at";
static final String TAG_USER_ID = "user_id";
static final String TAG_TIME = "";
ProgressDialog progressDialog;
Date mDateConvert;

// ...
HttpGet httpGet;
HttpEntity httpEntity;
HttpClient httpClient;
HttpResponse httpResponse;
StatusLine statusLine;
InputStream inputStream;

// to store in setters and getters
List<ModelClass> model = new ArrayList<ModelClass>();
ModelClass mc = null;

/* Data Base */
Cursor cursor = null;
String mDBRowId = null;
public static final String ID_EXTRA = "com.simbotix.leo._ID";
DataBaseNew dataBaseNew;
String dataBaseId = null;
// long listId = 0;

// ListView to display the feeds
ListView listViewFeeds;
NewAdapter adapter;
ArrayList<HashMap<String, String>> arrayListData;
String mTitle = null, mBody = null, mMediaType = null, mPriority = null,
        mDepartement = null, mTime = null, mDayDate = null, mDate = null;
CommunictionSingleView communictionSingleView;
// read - unread.
Boolean readUnread = false;

@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);
    communictionSingleView = (CommunictionSingleView) activity;
}

/*
 * (non-Javadoc)
 * 
 * @see
 * android.support.v4.app.Fragment#onCreateView(android.view.LayoutInflater,
 * android.view.ViewGroup, android.os.Bundle)
 */
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_feeds, container, false);
    return view;
}

/*
 * (non-Javadoc)
 * 
 * @see android.support.v4.app.Fragment#onActivityCreated(android.os.Bundle)
 */
@Override
public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    dataBaseNew = new DataBaseNew(getActivity());
    // To display the data json feeds
    listViewFeeds = (ListView) getActivity().findViewById(
            R.id.listViewFeeds);
    listViewFeeds.setOnItemClickListener(new OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view,
                int position, long id) {
            System.out.println("You selected " + position);
            mMediaType = ((TextView) view
                    .findViewById(R.id.textViewMediaType)).getText()
                    .toString();
            System.out.println("MediaType " + mMediaType);
            mDepartement = ((TextView) view
                    .findViewById(R.id.textViewDepartement)).getText()
                    .toString();
            System.out.println("Departement " + mDepartement);
            mTitle = ((TextView) view.findViewById(R.id.textViewTitleFeeds))
                    .getText().toString();
            System.out.println("Title " + mTitle);
            mBody = ((TextView) view.findViewById(R.id.textViewBody))
                    .getText().toString();
            System.out.println("Body " + mBody);
            mPriority = ((TextView) view
                    .findViewById(R.id.textViewPriority)).getText()
                    .toString();
            System.out.println("Priority " + mPriority);
            communictionSingleView.onSingleView(mMediaType, mDepartement,
                    mDayDate, mTime, mPriority, mTitle, mBody);
            readUnread = true;
            // listId = id;
            System.out.println("id: " + id);
        }
    });
    arrayListData = new ArrayList<HashMap<String, String>>();
    // Getting adapter by passing data to ArrayList
    adapter = new NewAdapter((MainActivity) getActivity(), arrayListData);
    if (CheckInternetConnection.isInternetConnected(getActivity())) {
        Feeds feeds = new Feeds();
        feeds.execute();
    } else {
        Toast.makeText(getActivity(),
                getString(R.string.check_internet_connection),
                Toast.LENGTH_SHORT).show();
    }
}

class Feeds extends AsyncTask<Void, Void, Void> {

    @Override
    protected void onPreExecute() {
        progressDialog = new ProgressDialog(getActivity());
        progressDialog.setMessage("Loading...");
        progressDialog.setCancelable(false);
        progressDialog.show();
        super.onPreExecute();
    }

    @SuppressLint("SimpleDateFormat")
    @Override
    protected Void doInBackground(Void... arg0) {
        httpClient = new DefaultHttpClient();
        httpGet = new HttpGet(url);
        httpGet.setHeader("Accept", "application/json");

        try {
            httpResponse = httpClient.execute(httpGet);
            statusLine = httpResponse.getStatusLine();
            int statusCode = statusLine.getStatusCode();
            if (statusCode != 200) {
                Toast.makeText(getActivity(), "error" + statusCode,
                        Toast.LENGTH_SHORT).show();
                return null;
            }
            httpEntity = httpResponse.getEntity();
            inputStream = httpEntity.getContent();
            BufferedReader bufferedReader = new BufferedReader(
                    new InputStreamReader(inputStream));
            StringBuilder stringBuilder = new StringBuilder();
            String line;
            while ((line = bufferedReader.readLine()) != null) {
                stringBuilder.append(line);
            }
            String jsonData = stringBuilder.toString();
            Log.d("Latest 20 feeds", jsonData);

            JSONArray array = new JSONArray(jsonData);
            for (int i = 0; i < array.length(); i++) {
                JSONObject object = array.getJSONObject(i);
                mTitle = object.getString(TAG_TITLE);
                mBody = object.getString(TAG_BODY);
                mDate = object.getString(TAG_DATE_TIME);
                mPriority = object.getString(TAG_PRIORITY);

                // Formatting date and time
                SimpleDateFormat formatter = new SimpleDateFormat(
                        "yyyy-MM-dd'T'HH:mm:ss'Z'");
                String dateInString = mDate;//
                try {
                    mDateConvert = formatter.parse(dateInString);

                    System.out.println("Date: " + mDateConvert);
                    SimpleDateFormat dayDateFormat = new SimpleDateFormat(
                            "E, MMM dd");// Tue, Apr 22.
                    mDayDate = dayDateFormat.format(mDateConvert);
                    System.out.println("Custom date: " + mDayDate);
                    SimpleDateFormat timeFormat = new SimpleDateFormat(
                            "HH:mm:ss");// hh:mm:ss
                    mTime = timeFormat.format(mDateConvert);
                    System.out.println("Time: " + mTime);
                } catch (ParseException e) {
                    e.printStackTrace();
                } catch (java.text.ParseException e) {
                    e.printStackTrace();
                }

                mMediaType = object.getString(TAG_MEDI_TYPE);
                mDepartement = object.getString(TAG_DEPARTEMENT);
                String mDate = object.getString(TAG_DATE_TIME);
                System.out.println("Titlte: " + mTitle);
                System.out.println("Body: " + mBody);
                System.out.println("MediaType: " + mMediaType);
                System.out.println("Priority: " + mPriority);
                System.out.println("Departement: " + mDepartement);
                // System.out.println("Date and Time" + mDate);

                // creating new HashMap
                HashMap<String, String> map = new HashMap<String, String>();
                map.put(TAG_TITLE, mTitle);
                map.put(TAG_BODY, mBody);
                map.put(TAG_PRIORITY, mPriority);
                map.put(TAG_DEPARTEMENT, mDepartement);
                map.put(TAG_DATE_TIME, mDayDate);
                map.put(TAG_TIME, mTime);
                map.put(TAG_MEDI_TYPE, mMediaType);

                System.out.println("clone " + map.clone());
                System.out.println("containsKey " + map.containsKey(map));
                System.out.println("containsValue "
                        + map.containsValue(map));
                System.out.println("entrySet " + map.entrySet());
                System.out.println("keySet " + map.keySet());

                arrayListData.add(map);

                // title , body , date , time , mediatype , priority ,
                // departement, readunread
                /* Data Base */
                // inserting in to data base
                // dataBaseId = getActivity().getIntent().getStringExtra(
                // MainActivity.ID_EXTRA);

                // dataBaseId = String.valueOf(listId);
                if (dataBaseId == null) {
                    dataBaseNew.insert(mTitle, mBody, mMediaType,
                            mPriority, mDepartement, mDayDate, mTime,
                            readUnread);
                } else {
                    dataBaseNew.update(dataBaseId, mTitle, mBody,
                            mMediaType, mPriority, mDepartement, mDayDate,
                            mTime, readUnread);
                }

            }

        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (JSONException e) {
            e.printStackTrace();
        }
        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        progressDialog.dismiss();
        listViewFeeds.setAdapter(adapter);
        super.onPostExecute(result);
    }
}

interface CommunictionSingleView {
    public void onSingleView(String mediaType, String departement,
            String dayDate, String time, String priority, String title,
            String body);
}

@Override
public void onStop() {
    super.onStop();
    try {
        inputStream.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
}}

---

}

您的

数据库ID

始终为

空

。您没有更改它，因此它总是进入

if

条件并插入到数据库中，而不是更新

---

您为其分配任何内容的行已被注释。

收到。另外，你能推荐一个例子吗

public class DataBaseNew {
DBHelper helper;

public DataBaseNew(FragmentActivity activity) {
    helper = new DBHelper(activity);
}

public long insert(String title, String body, String mediaType,
        String priority, String departement, String dayDate, String time,
        Boolean readUnread) {
    SQLiteDatabase db = helper.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put(DBHelper.TITLE, title);
    contentValues.put(DBHelper.BODY, body);
    contentValues.put(DBHelper.MEDIATYPE, mediaType);
    contentValues.put(DBHelper.PRIORITY, priority);
    contentValues.put(DBHelper.DEPARTEMENT, departement);
    contentValues.put(DBHelper.DAYDATE, dayDate);
    contentValues.put(DBHelper.TIME, time);
    contentValues.put(DBHelper.READUNREAD, readUnread);
    long id = db.insert(DBHelper.TABLE_NAME, null, contentValues);
    return id;

}

public long update(String dataBaseId, String mTitle, String mBody,
        String mMediaType, String mPriority, String mDepartement,
        String mDayDate, String mTime, Boolean readUnread) {
    SQLiteDatabase db = helper.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put(DBHelper.TITLE, mTitle);
    contentValues.put(DBHelper.BODY, mBody);
    contentValues.put(DBHelper.MEDIATYPE, mMediaType);
    contentValues.put(DBHelper.PRIORITY, mPriority);
    contentValues.put(DBHelper.DEPARTEMENT, mDepartement);
    contentValues.put(DBHelper.DAYDATE, mDayDate);
    contentValues.put(DBHelper.TIME, mTime);
    contentValues.put(DBHelper.READUNREAD, readUnread);
    ModelClass mc = null; //= new ModelClass();
    String[] whereArgs = { dataBaseId };
    long id = db.update(DBHelper.TABLE_NAME, contentValues, " _ID=?", 
            new String[] { String.valueOf(mc.getId())});
    return id;
}}

class DBHelper extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "feeddatabase";
static final String TABLE_NAME = "FEEDTABLE";
private static final int DATABASE_VERSION = 1;
static final String TITLE = "Title";
static final String BODY = "Body";
static final String MEDIATYPE = "MediaType";
static final String PRIORITY = "Priority";
static final String DEPARTEMENT = "Departement";
static final String DAYDATE = "DayDate";
static final String TIME = "Time";
static final String READUNREAD = "ReadUnread";
// private static final String FLAG = "Flag";
private static final String CREATE_TABLE = "CREATE TABLE " + TABLE_NAME
        + " (_id INTEGER PRIMARY KEY AUTOINCREMENT, " + TITLE
        + " VARCHAR(255), " + BODY + " VARCHAR(255)," + MEDIATYPE
        + " VARCHAR(255)," + PRIORITY + " VARCHAR(255)," + DEPARTEMENT
        + " VARCHAR(255)," + DAYDATE + " VARCHAR(255)," + TIME
        + " VARCHAR(255)," + READUNREAD + ");";
private Context context;

public DBHelper(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
    this.context = context;
}

@Override
public void onCreate(SQLiteDatabase db) {
    try {
        db.execSQL(CREATE_TABLE);
    } catch (SQLException e) {
        e.printStackTrace();
    }
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // TODO Auto-generated method stub

}