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我有一個方法從sqlite數據庫提取記錄,但過了一段時間後,我改變了一點,並提出了一個用用戶輸入的信息獲取特定記錄的輔助方法。Android; SQLite數據庫遊標爲空。它不應該。我不知道爲什麼它是
我不知道爲什麼,但我原來的方法現在返回null。
CardDbAdapter:
public CarddbAdapter open2() throws SQLException {
String myPath = DB_PATH + DB_NAME;
myDatabaseR = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.OPEN_READONLY);
myDatabaseW = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.OPEN_READWRITE);
return this;
}
public void MyDatabaseClose() {
myDatabaseW.close();
myDatabaseR.close();
}
public ArrayList<String> getAllCardNames() {
ArrayList<String> returnedAllCardNames;
ArrayList<String> NoResults;
ArrayList<String> NoResults2;
NoResults = new ArrayList<String>();
NoResults.add("cursor is null");
NoResults2 = new ArrayList<String>();
NoResults2.add("No similar cards found.");
returnedAllCardNames = new ArrayList<String>();
/*String sqlquery_cardNames = "SELECT " + KEY_CARDNAME
+ " FROM cards WHERE card_name like '%" + passedName
+ "%' ORDER BY card_name ASC";*/
//String sqlquery_cardNames;
String sqlquery_cardNames = "SELECT DISTINCT card_name FROM cards";
Cursor c_cardNames;
c_cardNames = myDatabaseW.rawQuery(sqlquery_cardNames, null);
c_cardNames.moveToFirst();
if (c_cardNames != null) {
do {
if (c_cardNames.getCount() > 0) {
String returnedName = c_cardNames.getString(c_cardNames
.getColumnIndex(KEY_CARDNAME));
returnedAllCardNames.add(returnedName);
} else {
return NoResults2;
}
} while (c_cardNames.moveToNext());
}
return NoResults;
}
如何我使用它:
CarddbAdapter yugiohDB = new CarddbAdapter(this);
yugiohDB.open2();
search_results = (ListView) findViewById(R.id.lvSearchResults);
search_results.setOnItemClickListener(this);
ArrayList<String> returnedCards_list1 = new ArrayList<String>();
returnedCards_list1.addAll(yugiohDB.getAllCardNames());
listAdapter = new ArrayAdapter<String>(SearchMode_Simple.this,
android.R.layout.simple_list_item_1, returnedCards_list1);
search_results.setAdapter(listAdapter);
yugiohDB.MyDatabaseClose();
任何幫助,將不勝感激。
如果你想看看這實際上應該做什麼,然後下載我的應用程序稱爲Yugioh圖書館+工具。點擊主菜單中的搜索庫按鈕,然後點擊簡單搜索按鈕。它應該顯示數據庫中的卡片列表。
我改變它的原因是因爲我設置了Spinners,所以用戶可以選擇不同的交易卡組來選擇一些列表,然後列出來自該特定組的所有卡。