我正在为 Android 开发一个简单的购物应用程序。该应用程序需要两个 SQLite 数据库表，但我没有同时创建它们（最初只为 MainActivity 创建了一个）。在网上搜索后，我了解到我们必须使用 SQLiteOpenHelper 类同时为数据库创建多个表。这种说法是真的吗？
如果不是，请检查下面的代码并为我的错误提出解决方案 -
该应用程序有两个活动，MainActivity.java和ItemsActivity.java，一个 DatabaseAdapter( DBAdapter.java ) 类。DatabaseAdapter 类有两个表，MainActivity 类使用名为TABLE_NAME的第一个表，ItemsActivity 类使用 DBAdapter 类中名为TABLE_NAME_ITEMS的第二个表。
ItemsActivity.java 是我将项目插入到 DBAdapter 中名为 TABLE_NAME_ITEMS 的第二个表中的类。这是ItemsActivity.java类
public class ItemsActivity extends Activity implements OnClickListener{
DBAdapter dbAdapterItems;
String listId;
//Cursor cItems;
//MyItemsAdapter adapter;
int position;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.items_activity);
dbAdapterItems = new DBAdapter(this);
dbAdapterItems.openDatabase();
Intent itemsActivity = getIntent();
Bundle b = itemsActivity.getExtras();
listId = b.getString("LIST_ID");
Button addItem = (Button) findViewById(R.id.addItemButton);
/* ListView itemslist = (ListView)findViewById(R.id.itemsListView);
cItems = dbAdapter.getAllItemRecords(listId);
adapter = new MyItemsAdapter();
itemslist.setAdapter(adapter);
**/
addItem.setOnClickListener(this);
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
// TODO Auto-generated method stub
final Dialog d = new Dialog(ItemsActivity.this);
d.setTitle("Add Item");
d.setContentView(R.layout.customdialog);
d.show();
final EditText itemNameEt = (EditText) d.findViewById(R.id.dialogEditText);
Button addButton = (Button) d.findViewById(R.id.dialogAddButton);
Button cancelButton = (Button) d.findViewById(R.id.dialogCancelButton);
addButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
String itemName = itemNameEt.getText().toString();
dbAdapterItems.insertItemsRecord(itemName,listId);
Toast.makeText(ItemsActivity.this, "Item name: "+itemName+" added", Toast.LENGTH_LONG).show();
d.dismiss();
}
});
cancelButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
d.dismiss();
Toast.makeText(ItemsActivity.this, listId, Toast.LENGTH_LONG).show();
}
});
}
/**
class MyItemsAdapter extends BaseAdapter{
@Override
public int getCount() {
// TODO Auto-generated method stub
return cItems.getCount();
}
@Override
public Object getItem(int arg0) {
// TODO Auto-generated method stub
return null;
}
@Override
public long getItemId(int arg0) {
// TODO Auto-generated method stub
return 0;
}
@Override
public View getView(int position, View view, ViewGroup parent) {
// TODO Auto-generated method stub
if(view==null){
LayoutInflater inflater = getLayoutInflater();
view = inflater.inflate(R.layout.custom_items_row, parent, false);
}
TextView itemsRowTv = (TextView) view.findViewById(R.id.customitemsrowTV);
cItems.moveToPosition(position);
String itemName = cItems.getString(1);
itemsRowTv.setText(itemName);
return view;
}
}
**/
}
这是DBAdapter.java类
public class DBAdapter {
String DATABASE_NAME = "SeenuDB";
String TABLE_NAME = "listTable"; //First Table Name
int DATABASE_VERSION = 1;
String TABLE_NAME_ITEMS = "itemsTable"; //Second Table Name
String COLUMN_ITEMS_ONE = "rowitemsid";
String COLUMN_ITEMS_TWO = "itemname";
String COLUMN_ITEMS_THREE = "listid";
public static final String COLUMN_ONE = "rowid";
public static final String COLUMN_TWO = "listname";
SQLiteDatabase db;
Context context;
DBHelper dbHelper;
String CREATE_TABLE = "create table if not exists listTable(rowid integer primary key autoincrement,listname text not null)";
String CREATE_TABLE_ITEMS = "create table if not exists " +TABLE_NAME_ITEMS+ "(rowitemsid integer primary key autoincrement,itemname text not null,listid text not null);";
public DBAdapter(Context c) {
// TODO Auto-generated constructor stub
this.context = c;
dbHelper = new DBHelper(context);
}
class DBHelper extends SQLiteOpenHelper{
public DBHelper(Context context) {
// TODO Auto-generated constructor stub
super(context,TABLE_NAME,null,DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
db.execSQL(CREATE_TABLE);
db.execSQL(CREATE_TABLE_ITEMS);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
db.execSQL("DROP TABLE IF EXISTS "+TABLE_NAME);
db.execSQL("DROP TABLE IF EXISTS "+TABLE_NAME_ITEMS);
onCreate(db);
}
}
DBAdapter openDatabase(){
db = dbHelper.getWritableDatabase();
return this;
}
void closeDatabase(){
dbHelper.close();
}
long insertRecord(String listname){
ContentValues con = new ContentValues();
con.put(COLUMN_TWO, listname);
return db.insert(TABLE_NAME, null, con);
}
Cursor getAllRecords(){
String[] columns = {COLUMN_ONE,COLUMN_TWO};
return db.query(TABLE_NAME, columns, null, null, null, null, null);
}
void deleteAllRecords(){
db.delete(TABLE_NAME, null, null);
}
void deleteOneRecord(String rowid){
db.delete(TABLE_NAME, rowid+"="+COLUMN_ONE, null);
}
long insertItemsRecord(String itemname,String listid){
ContentValues con = new ContentValues();
con.put(COLUMN_ITEMS_TWO, itemname);
con.put(COLUMN_ITEMS_THREE, listid);
return db.insert(TABLE_NAME_ITEMS, null, con);
}
Cursor getAllItemRecords(String listid){
String[] columns = {COLUMN_ITEMS_ONE,COLUMN_ITEMS_TWO,COLUMN_ITEMS_THREE};
return db.query(TABLE_NAME_ITEMS, columns, listid+"="+COLUMN_ITEMS_THREE, null, null, null, null);
}
}
使用第一个表我能够执行所有 CURD 操作，但是在使用第二个表执行插入操作时，我在 LogCat 中收到错误 no such tableitesTable。
希望读者理解我的问题，请为我提供解决方案..