下面的代码是我的databasehandler类,我从教程中得到它。除了那个教程,我在很多论坛中看到了这种方法。但是,即使我有创建表,它似乎也没有创建。我的错误可以帮助我。
public class DatabaseHandler extends SQLiteOpenHelper implements
DatabaseHandlerInterface {
// All Static variables
// Database Version
private static final int DATABASE_VERSION = 1;
// Database Name
private static final String DATABASE_NAME = "AACDroidDB";
// Contacts table name
private static final String TABLE_CONTACTS = "contacts";
private static final String TABLE_PHRASES = "phrase";
// Phrase Table Columns names
private static final String KEY_PHRASE_ID = "id";
private static final String KEY_PHRASE_STARTLETTER = "startLetter";
private static final String KEY_PHRASE_FULLPHRASE = "fullPhrase";
private static final String KEY_PHRASE_USAGECOUNT = "usageCount";
private static final String KEY_PHRASE_ISFAMOUS = "isFamous";
private static final String KEY_PHRASE_CREATEDATE = "createDate";
private static final String KEY_PHRASE_LASTUSAGEDATE = "lastUsageDate";
// Contacts Table Columns names
private static final String KEY_ID = "id";
private static final String KEY_NAME = "name";
private static final String KEY_PH_NO = "phone_number";
public DatabaseHandler(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
// Creating Tables
@Override
public void onCreate(SQLiteDatabase db) {
String CREATE_PHRASES_TABLE = "CREATE TABLE " + TABLE_PHRASES + "("
+ KEY_PHRASE_ID + " INTEGER PRIMARY KEY,"
+ KEY_PHRASE_STARTLETTER + " text, "
+ KEY_PHRASE_FULLPHRASE + " text, "
+ KEY_PHRASE_USAGECOUNT + " integer, "
+ KEY_PHRASE_ISFAMOUS + " integer, "
+ KEY_PHRASE_CREATEDATE + " text, " + KEY_PHRASE_LASTUSAGEDATE
+ " text" + ");";
db.execSQL(CREATE_PHRASES_TABLE);
Log.d(Constants.DB_LOG, "database created");
}
// Upgrading database
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// Drop older table if existed
db.execSQL("DROP TABLE IF EXISTS " + TABLE_CONTACTS);
db.execSQL("DROP TABLE IF EXISTS " + TABLE_PHRASES);
// Create tables again
onCreate(db);
}
/**
* All CRUD(Create, Read, Update, Delete) Operations
*/
// Adding new phrase
public void addPhrase(Phrase phrase) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(KEY_PHRASE_STARTLETTER, phrase.getStartletter());
values.put(KEY_PHRASE_FULLPHRASE, phrase.getFullphrase());
values.put(KEY_PHRASE_USAGECOUNT, phrase.getUsagecount());
values.put(KEY_PHRASE_ISFAMOUS, phrase.getIsFamous());
values.put(KEY_PHRASE_CREATEDATE, phrase.getCreateDate());
values.put(KEY_PHRASE_LASTUSAGEDATE, phrase.getLastUsageDate());
//
db.insert(TABLE_PHRASES, null, values);
db.close(); // Closing database connection
}
// getting new phrase
public Phrase getPhrase(int idForPhrase) {
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(TABLE_PHRASES, new String[] { KEY_PHRASE_ID,
KEY_PHRASE_STARTLETTER, KEY_PHRASE_FULLPHRASE,
// KEY_PHRASE_USAGECOUNT,
KEY_PHRASE_ISFAMOUS,
// KEY_PHRASE_CREATEDATE,
KEY_PHRASE_LASTUSAGEDATE }, KEY_PHRASE_ID + "=?",
new String[] { String.valueOf(idForPhrase) }, null, null, null,
null);
if (cursor != null)
cursor.moveToFirst();
// int id = Integer.parseInt(cursor.getString(0));
String startLetter = cursor.getString(1);
String fullPhrase = cursor.getString(2);
// int usageCount = Integer.parseInt(cursor.getString(3));
// int isFamous = Integer.parseInt(cursor.getString(4));
// String createDate = cursor.getString(5);
// String lastUsageDate = cursor.getString(6);
Phrase phrase = new Phrase();
// phrase.setId(id);
phrase.setStartletter(startLetter);
phrase.setFullphrase(fullPhrase);
// phrase.setUsagecount(usageCount);
// phrase.setIsFamous(isFamous);
// phrase.setCreateDate(createDate);
// phrase.setLastUsageDate(lastUsageDate);
// return contact
return phrase;
}
// Updating single contact
public int updatePhrase(Phrase phrase) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(KEY_PHRASE_STARTLETTER, phrase.getStartletter());
values.put(KEY_PHRASE_FULLPHRASE, phrase.getFullphrase());
values.put(KEY_PHRASE_USAGECOUNT, phrase.getUsagecount());
values.put(KEY_PHRASE_ISFAMOUS, phrase.getIsFamous());
values.put(KEY_PHRASE_CREATEDATE, phrase.getCreateDate());
values.put(KEY_PHRASE_LASTUSAGEDATE, phrase.getLastUsageDate());
// updating row
return db.update(TABLE_PHRASES, values, KEY_PHRASE_ID + " = ?",
new String[] { String.valueOf(phrase.getId()) });
}
}
答案 0 :(得分:1)
在获得对数据库的引用之前,不会调用onCreate(...)
的{{1}}方法。
在SQLiteHelper
中创建帮助程序的实例,然后从中获取可写数据库,如下所示......
Activity
顺便说一句,如果您打算使用游标,我建议您使用名称“_id”作为数据库ID列。在Android中,DatabaseHandler myHelper = new DatabaseHandler(this);
SQLiteDatabase db = myHelper.getWritableDatabase();
必须有一个专门称为Cursor
的列才能正常工作。在创建表时使用该特定名称意味着您不必在SQL查询中对列名称进行“别名”。
答案 1 :(得分:0)
只有在设备上首次创建数据库时才会调用onCreate()方法。尝试从设置清除设备上的本地数据 - >应用程序 - >管理应用程序
您也可以更改数据库版本。