在TextView中顯示數據庫中的值[Android]

Question

我試圖從應用程序本身內創建的數據庫活動中顯示值。這些值最初是從XML文件中解析出來的，然後存儲在數據庫中。我做了大量的搜索，並嘗試了幾種解決方案，但我似乎被卡住了。如果有人能幫助我，那會很棒！

Q，（I）選擇ListView中的項目後，必須在TextView中顯示值。爲此，我在ListView Activity（ListRSSItemsActivity）中設置了一個onItemClickListener，並且打算啓動新的活動，並創建相應的佈局文件。我或多或少熟悉如何讓TextView工作。但是，我不確定現在應該將什麼放入新活動（ArticleActivity）文件中。 （II）當我點擊該項目並打開新窗口時，它會顯示一個空白屏幕。

我附加了新的活動類和佈局文件。

ArticleActivity：

public class ArticleActivity extends Activity{ 


    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     this.requestWindowFeature(Window.FEATURE_NO_TITLE); 
     setContentView(R.layout.article_view); 

     String title, description; 

     title=this.getIntent().getStringExtra("TAG_TITLE"); 
     description=this.getIntent().getStringExtra("TAG_DESCRIPTION");  
} 
} 

article_view.xml：

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:orientation="vertical" > 

    <!-- Article Title --> 
    <TextView android:id="@+id/title" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:paddingTop="10dp" 
     android:paddingBottom="8dp" 
     android:textSize="18sp" 
     android:textStyle="bold" 
     android:textColor="#dc6800"/> 

    <!-- Article Content --> 
    <TextView android:id="@+id/description" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:textColor="#acacac" 
     android:layout_below="@id/title"/> 
</RelativeLayout> 

ListRSSItemsActivity：

public class ListRSSItemsActivity extends ListActivity { 

    // Progress Dialog 
    private ProgressDialog pDialog; 

    // Array list for list view 
    ArrayList<HashMap<String, String>> rssItemList = new ArrayList<HashMap<String,String>>(); 

    RSSParser rssParser = new RSSParser(); 

    List<RSSItem> rssItems = new ArrayList<RSSItem>(); 

    RSSFeed rssFeed; 

    public static String TAG_TITLE = "title"; 
    private static String TAG_LINK = "link"; 
    private static String TAG_DESCRIPTION = "description"; 
    private static String TAG_PUBDATE = "pub_date"; 
    private static String TAG_GUID = "guid"; // not used 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     this.requestWindowFeature(Window.FEATURE_NO_TITLE); 
//  setContentView(R.layout.rss_item_list); 

     // get intent data 
     Intent i = getIntent(); 

     // SQLite Row id 
     Integer site_id = Integer.parseInt(i.getStringExtra("id")); 

     // Getting Single website from SQLite 
     RSSDatabaseHandler rssDB = new RSSDatabaseHandler(getApplicationContext()); 


     WebSite site = rssDB.getSite(site_id); 
     String rss_link = site.getRSSLink(); 

     /** 
     * Calling a backgroung thread will loads recent articles of a website 
     * @param rss url of website 
     * */ 
     new loadRSSFeedItems().execute(rss_link); 

     // selecting single ListView item 
     ListView lv = getListView(); 

     // Launching new screen on Selecting Single ListItem 
     lv.setOnItemClickListener(new OnItemClickListener() { 

      public void onItemClick(AdapterView<?> parent, View view, 
        int position, long id) { 

       // getting listview 
       View v = (View)view.getParent(); 
       TextView tv = (TextView)v.findViewById(R.id.title); 
       String title = tv.getText().toString(); 
       String description = ((TextView) view.findViewById(R.id.link)).getText().toString(); 

       // Starting new intent 
       Intent ia = new Intent(getApplicationContext(), ArticleActivity.class); 
       ia.putExtra("TAG_TITLE", title); 
       ia.putExtra("TAG_DESCRIPTION", description); 
       startActivity(ia);    
      } 
     }); 
    } 

    /** 
    * Background Async Task to get RSS Feed Items data from URL 
    * */ 
    class loadRSSFeedItems extends AsyncTask<String, String, String> { 

     /** 
     * Before starting background thread Show Progress Dialog 
     * */ 
     @Override 
     protected void onPreExecute() { 
      super.onPreExecute(); 
      pDialog = new ProgressDialog(
        ListRSSItemsActivity.this); 
      pDialog.setMessage("Loading recent articles..."); 
      pDialog.setIndeterminate(false); 
      pDialog.setCancelable(false); 
      pDialog.show(); 
     } 

     /** 
     * getting all recent articles and showing them in listview 
     * */ 
     @Override 
     protected String doInBackground(String... args) { 
      // rss link url 
      String rss_url = args[0]; 

      // list of rss items 
      // using GET method to obtain rssfeeditems. NOTICE: only from RSS_URL here! 
      rssItems = rssParser.getRSSFeedItems(rss_url); 

      // looping through each item 
      for(RSSItem item : rssItems){ 
       // creating new HashMap 
       HashMap<String, String> map = new HashMap<String, String>(); 

       // adding each child node to HashMap key => value 
       map.put(TAG_TITLE, item.getTitle()); 
       map.put(TAG_LINK, item.getLink()); 
       map.put(TAG_PUBDATE, item.getPubDate()); 

       String description = item.getDescription(); 
       // taking only 200 chars from description 
       if(description.length() > 100){ 
        description = description.substring(0, 97) + ".."; 
       } 
       map.put(TAG_DESCRIPTION, description); 


       // adding HashList to ArrayList 
       rssItemList.add(map); 
      } 

      // updating UI from Background Thread 
      runOnUiThread(new Runnable() { 
       public void run() { 
        /** 
        * Updating parsed items into listview 
        * */ 
        ListAdapter adapter = new SimpleAdapter(
          ListRSSItemsActivity.this, 
          rssItemList, R.layout.rss_item_list_row, 
          new String[] { TAG_LINK, TAG_TITLE, TAG_PUBDATE, TAG_DESCRIPTION }, 
          new int[] { R.id.page_url, R.id.title, R.id.pub_date, R.id.link }); 

        // updating listview 
        setListAdapter(adapter); 
       } 
      }); 
      return null; 
     } 

     /** 
     * After completing background task Dismiss the progress dialog 
     * **/ 
     protected void onPostExecute(String args) { 
      // dismiss the dialog after getting all products 
      pDialog.dismiss(); 
     } 
    } 
} 

數據庫活動：

public class RSSDatabaseHandler extends SQLiteOpenHelper{ 

    // Database Version 
    private static final int DATABASE_VERSION = 1; 

    // Database Name 
    private static final String DATABASE_NAME = "rssReader"; 

    // Contacts table name 
    private static final String TABLE_RSS = "websites"; 

    // Contacts Table Columns names 
    private static final String KEY_ID = "id"; 
    private static final String KEY_TITLE = "title"; 
    private static final String KEY_LINK = "link"; 
    private static final String KEY_RSS_LINK = "rss_link"; 
    private static final String KEY_DESCRIPTION = "description"; 
    private static final String KEY_PUBDATE = "pub_date"; 

    public RSSDatabaseHandler(Context context) { 
     super(context, DATABASE_NAME, null, DATABASE_VERSION); 
    } 

    // Creating Tables 
    @Override 
    public void onCreate(SQLiteDatabase db) { 
     String CREATE_RSS_TABLE = "CREATE TABLE " + TABLE_RSS + "(" + KEY_ID 
       + " INTEGER PRIMARY KEY," + KEY_TITLE + " TEXT," + KEY_LINK 
       + " TEXT," + KEY_RSS_LINK + " TEXT," + KEY_DESCRIPTION 
       + " TEXT," + KEY_PUBDATE + " TEXT" + ")"; 
     db.execSQL(CREATE_RSS_TABLE); 
    } 

    // Upgrading database 
    @Override 
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
     // Drop older table if existed 
     db.execSQL("DROP TABLE IF EXISTS " + TABLE_RSS); 

     // Create tables again 
     onCreate(db); 
    } 

    /** 
    * Adding a new website in websites table Function will check if a site 
    * already existed in database. If existed will update the old one else 
    * creates a new row 
    * */ 
    public void addSite(WebSite site) { 
     SQLiteDatabase db = this.getWritableDatabase(); 

     ContentValues values = new ContentValues(); 
     values.put(KEY_TITLE, site.getTitle()); // site title 
     values.put(KEY_LINK, site.getLink()); // site url 
     values.put(KEY_RSS_LINK, site.getRSSLink()); // rss link url 
     values.put(KEY_DESCRIPTION, site.getDescription()); // site description 
     values.put(KEY_PUBDATE, site.getPubDate()); 

     // Check if row already existed in database 
     if (!isSiteExists(db, site.getRSSLink())) { 
      // site not existed, create a new row 
      db.insert(TABLE_RSS, null, values); 
      db.close(); 
     } else { 
      // site already existed update the row 
      updateSite(site); 
      db.close(); 
     } 
    } 

    /** 
    * Reading all rows from database 
    * */ 
    public List<WebSite> getAllSites() { 
     List<WebSite> siteList = new ArrayList<WebSite>(); 
     // Select All Query 
     String selectQuery = "SELECT * FROM " + TABLE_RSS 
       + " ORDER BY id DESC"; 

     SQLiteDatabase db = this.getReadableDatabase(); 
     Cursor cursor = db.rawQuery(selectQuery, null); 

     // looping through all rows and adding to list 
     if (cursor.moveToFirst()) { 
      do { 
       WebSite site = new WebSite(); 
       site.setId(Integer.parseInt(cursor.getString(0))); 
       site.setTitle(cursor.getString(1)); 
       site.setLink(cursor.getString(2)); 
       site.setRSSLink(cursor.getString(3)); 
       site.setDescription(cursor.getString(4)); 
       site.setPubDate(cursor.getString(5)); 
       // Adding contact to list 
       siteList.add(site); 
      } while (cursor.moveToNext()); 
     } 
     cursor.close(); 
     db.close(); 

     // return contact list 
     return siteList; 
    } 

    /** 
    * Updating a single row row will be identified by rss link 
    * */ 
    public int updateSite(WebSite site) { 
     SQLiteDatabase db = this.getWritableDatabase(); 

     ContentValues values = new ContentValues(); 
     values.put(KEY_TITLE, site.getTitle()); 
     values.put(KEY_LINK, site.getLink()); 
     values.put(KEY_RSS_LINK, site.getRSSLink()); 
     values.put(KEY_DESCRIPTION, site.getDescription()); 
     values.put(KEY_PUBDATE, site.getPubDate()); 

     // updating row return 
     int update = db.update(TABLE_RSS, values, KEY_RSS_LINK + " = ?", 
       new String[] { String.valueOf(site.getRSSLink()) }); 
     db.close(); 
     return update; 

    } 

    /** 
    * Reading a row (website) row is identified by row id 
    * */ 
    // Declaring 
    public WebSite getSite(int id) { 
     SQLiteDatabase db = this.getReadableDatabase(); 

     Cursor cursor = db.query(TABLE_RSS, new String[] { KEY_ID, KEY_TITLE, 
       KEY_LINK, KEY_RSS_LINK, KEY_DESCRIPTION, KEY_PUBDATE }, KEY_ID + "=?", 
       new String[] { String.valueOf(id) }, null, null, null, null); 
     if (cursor != null) 
      cursor.moveToFirst(); 

     WebSite site = new WebSite(cursor.getString(1), cursor.getString(2), 
       cursor.getString(3), cursor.getString(4), cursor.getString(5)); 

     site.setId(Integer.parseInt(cursor.getString(0))); 
     site.setTitle(cursor.getString(1)); 
     site.setLink(cursor.getString(2)); 
     site.setRSSLink(cursor.getString(3)); 
     site.setDescription(cursor.getString(4)); 
     site.setPubDate(cursor.getString(5)); 
     cursor.close(); 
     db.close(); 
     return site; 
    } 

    /** 
    * Deleting single row 
    * */ 
    public void deleteSite(WebSite site) { 
     SQLiteDatabase db = this.getWritableDatabase(); 
     db.delete(TABLE_RSS, KEY_ID + " = ?", 
       new String[] { String.valueOf(site.getId())}); 
     db.close(); 
    } 

    /** 
    * Checking whether a site is already existed check is done by matching rss 
    * link 
    * */ 
    public boolean isSiteExists(SQLiteDatabase db, String rss_link) { 

     Cursor cursor = db.rawQuery("SELECT 1 FROM " + TABLE_RSS 
       + " WHERE rss_link = '" + rss_link + "'", new String[] {}); 
     boolean exists = (cursor.getCount() > 0); 
     return exists; 
    } 
} 

Answer 1

刪除這些行：

ia.putExtra("TAG_TITLE", "title"); 
    ia.putExtra("TAG_DESCRIPTION", "description"); 

，並與下面替換：

ia.putExtra("TAG_TITLE", title); 
    ia.putExtra("TAG_DESCRIPTION", description); 

更改代碼ArticleActivity：

刪除下面的代碼：

Bundle extras = getIntent().getExtras(); 
     if (extras != null) { 
      String value = extras.getString(TAG_TITLE, "title"); 

替換下面的代碼：

String title,description; 
TextView txtTitle,txtDesc; 

txtTitle=(TextView)findViewById(R.id.title); 
txtDesc=(TextView)findViewById(R.id.description); 

    title=this.getIntent().getStringExtra("TAG_TITLE"); 
    description=this.getIntent().getStringExtra("TAG_DESCRIPTON"); 

    txtTitle.setText(title); 
    txtDesc.setText(description); 
      } 

而在你尊重別人的TextView設置這些值或任何地方根據自己的需要。

Answer 2

嘗試以下
創建一個共享的偏好
把appropirate數據在列表項的共享偏好選擇收聽
在活動的OnCreate（其中ü要被顯示的數據），讀來自共享首選項的數據並根據您的需要顯示數據。