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。我開始編寫飲食計劃器項目，這是我的數據庫表。我使用外部數據庫並在那裏定義表外鍵並將其複製到資產文件夾中，然後將其連接到我的項目。 standardUnit，Foods和standardFoodUnit是3張有靜態數據的表格，我填充了它們，但EatenFood表格是在計算後動態填充的。 我使用模型類，並嘗試用androidhive database tutorial指令編寫databaseAdapter.but因爲我最近開始使用android，所以我對此沒有任何看法。嘗試閱讀書籍或在線教程，但他們混淆了我更多。現在這是我的問題，我想知道對於EatenFood表外鍵我怎麼能把food-id值？我在數據庫中定義food_id INTEGER REFERENCES Foods (_id)之前，但在databaseAdapter類中插入或更新或獲取函數我不知道如何可以與行爲這個外鍵。初始化動態表中的外鍵
這是EatenFood表模型類
public class EatenFood {
int eatenfoodid;
boolean breakfast;
boolean lunch;
boolean snack;
boolean appetizers;
boolean dinner;
Data day;
String equivalent;
boolean dairy;
boolean vegetables;
boolean fruit;
boolean meat_bean_egg;
boolean bread_cereals;
boolean fat;
boolean suger;
double unitsum;
int food_id;
public boolean isAppetizers() {
return appetizers;
}
public void setAppetizers(boolean appetizers) {
this.appetizers = appetizers;
}
public Data getDay() {
return day;
}
public void setDay(Data day) {
this.day = day;
}
public double getUnitsum() {
return unitsum;
}
public void setUnitsum(double unitsum) {
this.unitsum = unitsum;
}
public int getFood_id() {
return food_id;
}
public void setFood_id(int food_id) {
this.food_id = food_id;
}
//all remaining getter and setter .........}
模型類食物表
public class Foods {
int foodid;
String foodname;
boolean breakfast;
boolean lunch;
boolean snack;
boolean appetizers;
boolean dinner;
boolean mainfood;
boolean secondary;
public boolean isAppetizers() {
return appetizers;
}
public void setAppetizers(boolean appetizers) {
this.appetizers = appetizers;
}
public int getFoodid() {
return foodid;
}
public void setFoodid(int foodid) {
this.foodid = foodid;
}
//all remaining getter and setter .........}
DatabaseAdapter功能
public class DatabaseAdapter {
private final String TAG = "DatabaseAdapter";
private DatabaseOpenHelper openHelper;
public Long insertEatenFood(EatenFood eatenfood) {
SQLiteDatabase myDataBase = null;
Long id = -1L;
try {
ContentValues values = new ContentValues();
values.put(TABLE_EATENFOOD_BREAKFAST, eatenfood.isBreakfast());
values.put(TABLE_EATENFOOD_LUNCH, eatenfood.isLunch());
values.put(TABLE_EATENFOOD_SNACK, eatenfood.isSnack());
values.put(TABLE_EATENFOOD_APPETIZERS, eatenfood.isAppetizers());
values.put(TABLE_EATENFOOD_DINNER, eatenfood.isDinner());
// values.put(TABLE_EATENFOOD_DATA, eatenfood.getDay().getClass());
values.put(TABLE_EATENFOOD_EQUIVALENT, eatenfood.getEquivalent());
values.put(TABLE_EATENFOOD_DAIRY, eatenfood.isDairy());
values.put(TABLE_EATENFOOD_VEGETABLES, eatenfood.isVegetables());
values.put(TABLE_EATENFOOD_FRUIT, eatenfood.isFruit());
values.put(TABLE_EATENFOOD_MEAT_BEAN_EGG,
eatenfood.isMeat_bean_egg());
values.put(TABLE_EATENFOOD_BREAD_CEREALS,
eatenfood.isBread_cereals());
values.put(TABLE_EATENFOOD_FAT, eatenfood.isFat());
values.put(TABLE_EATENFOOD_SUGER, eatenfood.isSuger());
values.put(TABLE_EATENFOOD_UNITSUM, eatenfood.getUnitsum());
myDataBase = openHelper.getWritableDatabase();
id = myDataBase.insert(TABLE_EATENFOOD, null, values);
} catch (Exception e) {
Log.e(TAG, "Exception: " + e.getMessage());
} finally {
if (myDataBase != null && myDataBase.isOpen())
myDataBase.close();
}
return id;
}
// update EateanFood table =====================================================
public int updateEatenFood(EatenFood eatenfood) {
SQLiteDatabase myDataBase = null;
int count = -1;
try {
myDataBase = openHelper.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(TABLE_EATENFOOD_BREAKFAST, eatenfood.isBreakfast());
values.put(TABLE_EATENFOOD_LUNCH, eatenfood.isLunch());
values.put(TABLE_EATENFOOD_SNACK, eatenfood.isSnack());
values.put(TABLE_EATENFOOD_APPETIZERS, eatenfood.isAppetizers());
values.put(TABLE_EATENFOOD_DINNER, eatenfood.isDinner());
// values.put(TABLE_EATENFOOD_DATA, eatenfood.getDay().getClass());
values.put(TABLE_EATENFOOD_EQUIVALENT, eatenfood.getEquivalent());
values.put(TABLE_EATENFOOD_DAIRY, eatenfood.isDairy());
values.put(TABLE_EATENFOOD_VEGETABLES, eatenfood.isVegetables());
values.put(TABLE_EATENFOOD_FRUIT, eatenfood.isFruit());
values.put(TABLE_EATENFOOD_MEAT_BEAN_EGG,
eatenfood.isMeat_bean_egg());
values.put(TABLE_EATENFOOD_BREAD_CEREALS,
eatenfood.isBread_cereals());
values.put(TABLE_EATENFOOD_FAT, eatenfood.isFat());
values.put(TABLE_EATENFOOD_SUGER, eatenfood.isSuger());
values.put(TABLE_EATENFOOD_UNITSUM, eatenfood.getUnitsum());
count = myDataBase
.update(TABLE_EATENFOOD, values, TABLE_EATENFOOD_ID + "=?",
new String[] { String.valueOf(eatenfood
.getEatenfoodid()) });
} catch (Exception e) {
Log.e(TAG, "Exception: " + e.getMessage());
} finally {
myDataBase.close();
}
return count;
}
// Getting All EatenFood ================================================
public ArrayList<EatenFood> getEatenfoods() {
ArrayList<EatenFood> result = null;
SQLiteDatabase myDataBase = null;
Cursor cursor = null;
try {
myDataBase = openHelper.getWritableDatabase();
cursor = myDataBase.query(TABLE_EATENFOOD, new String[] { "*" }, null, null,
null, null, null);
if (cursor.moveToFirst()) {
result = new ArrayList<EatenFood>();
do {
result.add(extractEatenFood(cursor));
} while (cursor.moveToNext());
}
} catch (Exception e) {
Log.e(TAG, "Exception: " + e.getMessage());
}
finally {
if (cursor != null) {
cursor.close();
}
myDataBase.close();
}
return result;
}
// extractEatenFood=============================================================
private EatenFood extractEatenFood(Cursor cursor){
EatenFood eatenfood = new EatenFood();
eatenfood.setEatenfoodid(cursor.getInt(cursor.getColumnIndex(TABLE_EATENFOOD_ID)));
eatenfood.setBreakfast(cursor.getInt(cursor.getColumnIndex(TABLE_EATENFOOD_BREAKFAST)) != 0);
eatenfood.setLunch(cursor.getInt(cursor.getColumnIndex(TABLE_EATENFOOD_LUNCH))!=0);
eatenfood.setSnack(cursor.getInt(cursor.getColumnIndex(TABLE_EATENFOOD_SNACK))!=0);
eatenfood.setAppetizers(cursor.getInt(cursor.getColumnIndex(TABLE_EATENFOOD_APPETIZERS))!=0);
eatenfood.setDinner(cursor.getInt(cursor.getColumnIndex(TABLE_EATENFOOD_DINNER))!=0);
// ???????????????????????? baraye day k sabt beshe
eatenfood.setEquivalent(cursor.getString(cursor.getColumnIndex(TABLE_EATENFOOD_EQUIVALENT)));
eatenfood.setDairy(cursor.getInt(cursor.getColumnIndex(TABLE_EATENFOOD_DAIRY))!=0);
eatenfood.setVegetables(cursor.getInt(cursor.getColumnIndex(TABLE_EATENFOOD_VEGETABLES))!=0);
eatenfood.setFruit(cursor.getInt(cursor.getColumnIndex(TABLE_EATENFOOD_FRUIT))!=0);
eatenfood.setBread_cereals(cursor.getInt(cursor.getColumnIndex(TABLE_EATENFOOD_BREAD_CEREALS))!=0);
eatenfood.setFat(cursor.getInt(cursor.getColumnIndex(TABLE_EATENFOOD_FAT))!=0);
eatenfood.setSuger(cursor.getInt(cursor.getColumnIndex(TABLE_EATENFOOD_SUGER))!=0);
eatenfood.setFood_id(cursor.getInt(cursor.getColumnIndex(TABLE_EATENFOOD_F_FOODID)));
return eatenfood ;
}