我一直試圖編寫一個超級基本Android應用程序,當給定一個字符串時,讀取/搜索我從CUDict的133000字詞典中生成的sqlite3數據庫文件的「word」列,(在下面的示例中,我將搜索與單詞列中的「Hello」相對應的代碼列條目),並輸出logcat相應的條目。我知道我有一些方法來設置數據庫中的值,但我的目標是簡單地搜索我已經擁有的數據庫。在Android中讀取常量SQLite3數據庫文件
在終端,我可以做
kizzlebot$ sqlite3 cmudict.0.7a.sqlite3
> SELECT code FROM cmudict WHERE word="HELLO"
搜索數據庫。它返回正確的值。
但是當我運行我的程序時,它只是立即崩潰。 logcat說我有一個cursorIndexOutofBounds錯誤。我不知道我在做什麼錯,因爲我不太擅長閱讀logcat輸出。
我已將「cmudict.0.7a.sqlite3」放置在與AndroidManifest.xml位於同一級別的資產目錄中。如果在需要引用sqlite3文件的任何xml文件中需要做其他聲明,我不太肯定。我不知道數據庫文件是否被發現,但似乎是這樣,因爲在/ data/data/packageName /數據庫中我有一個cmudict.0.7a文件。
/*
* File: DatabaseHandler.java
*/
public class DatabaseHandler extends SQLiteOpenHelper {
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "cmudict.0.7a.sqlite";
private static final String TABLE_DICTS = "cmudict";
private static final String KEY_ID = "id";
private static final String KEY_WORD = "word";
private static final String KEY_CODE = "code";
public DatabaseHandler(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
// Creating Tables
@Override
public void onCreate(SQLiteDatabase db) {
String CREATE_WORDS_TABLE = "CREATE TABLE " + TABLE_DICTS + "("
+ KEY_ID + " INTEGER PRIMARY KEY," + KEY_WORD + " TEXT,"
+ KEY_CODE+ " TEXT" + ")";
db.execSQL(CREATE_WORDS_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_DICTS);
// Create tables again
onCreate(db);
}
public void addWord(Word word) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(KEY_WORD, word.getWord()); //
values.put(KEY_CODE, word.getCode()); //
// Inserting Row
db.insert(TABLE_DICTS, null, values);
db.close(); // Closing database connection
}
public Word getWord(String word) {
SQLiteDatabase db = this.getReadableDatabase();
String sqlQuery = "SELECT "+KEY_CODE+" FROM "+TABLE_DICTS+" WHERE "+KEY_WORD+"=?";
String[] r = {word};
Cursor cursor = db.rawQuery(sqlQuery,r);
// ERROR on this line I think: cursorIndexOutofBounds
Word aWord = new Word(cursor.getString(0), cursor.getString(1));
// Can't reach here.
Log.d("!!!!!MAJOR AVOIDED ERROR HERE", "SHIIIIIIT");
// return contact
return aWord;
}
}
這裏是一類稱爲字包含在SQLite數據庫的單個行(即ID,字,代碼)的屬性。以及獲取者和設置者
/*
* File: Word.java
* Desription: SQLite3 database has columns "_id", "word", "code" (Arpabet representation). This class encapsulates a single row of the sqlite database
*/
public class Word{
//private variables
int _id;
String _word;
String _code;
// Empty constructor
public Word(){
}
// Overridden constructor
public Word(int id, String word, String code){
this._id = id;
this._word = word;
this._code= code;
}
// constructor
public Word(String word, String code){
this._word = word;
this._code= code;
}
// getting ID
public int getID(){
return this._id;
}
// setting id
public void setID(int id){
this._id = id;
}
// getting word
public String getWord(){
return this._word;
}
// setting word
public void setWord(String word){
this._word = word ;
}
// getting code
public String getCode(){
return this._code;
}
// setting code
public void setCode(String code){
this._code = code;
}
}
這是活動。我只是用它來測試是否可以得到「Word」列對應的「代碼」列以打印到logcat。
/*
* File: MyActivity.java
*/
public class MyActivity extends Activity {
@Override
public void onCreate (Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
DatabaseHandler db = new DatabaseHandler(this);
Word wrd = db.getWord("HELLO"); // I simply want to query the database for the word "HELLO", which I know for a fact is in the database because I can find it using desktop app.
Log.d("!!!!!!!!!!!",Word.getString().toString());
}
}
我知道它有很多代碼要求有人閱讀,所以提前謝謝。我出來的想法,我很新的Android開發和SQLite
我試過你」 ve說,把這個if語句放在rawQuery方法調用之後,但我仍然得到錯誤,引用了Java NullPointerException。它在聲明wrd.getCode()方法調用時聲明瞭它。然後logcat顯示一堆「權限被拒絕:checkComponentPermission()owningUid = 10037」行。 –
好吧,我得到的應用程序完全讀取sqlite文件,但只有我通過adb push替換/data/data/com.ex.app/database/sqlitefile.sqlite。爲什麼我的sqlite文件沒有與應用程序一起安裝? –