从sqlite android中的表中获取单行

Question

我最近开始学习android,所以我不知道如何处理这个问题.我想知道如何从数据库中的一个表中获取单行我读了androidhive数据库教程并尝试编写我的代码,例如示例代码,但是当我想写"获取单行"部分时我面临一些问题.

这是我的模特课

public class UserMealUnit {
 int mealid;
 boolean breakfast;
 boolean lunch;
 float vegetables;
 public int getMealid() {
    return mealid;
}
public void setMealid(int mealid) {
    this.mealid = mealid;
}
public boolean isBreakfast() {
    return breakfast;
}
public void setBreakfast(boolean breakfast) {
    this.breakfast = breakfast;
}
public boolean isLunch() {
    return lunch;
}
public void setLunch(boolean lunch) {
    this.lunch = lunch;
}
    public float getVegetables() {
    return vegetables;
}
public void setVegetables(float vegetables) {
    this.vegetables = vegetables;
}

这是我的databaseAdapter代码getting single row部分

UserMealUnit getusermealunit(int mealid){
        SQLiteDatabase myDataBase = null;
        myDataBase = openHelper.getWritableDatabase();
        Cursor cursor=myDataBase.query(TABLE_USERMEALUNIT, new String[] {TABLE_USERMEALUNIT_ID,
                TABLE_USERMEALUNIT_BREAKFAST,
                TABLE_USERMEALUNIT_LUNCH,
                TABLE_USERMEALUNIT_VEGETABLES,

                }, TABLE_USERMEALUNIT_ID + "=?",  new String[] { String.valueOf(mealid) },
                 null, null, null, null);
         if (cursor != null)
                cursor.moveToFirst();            
         UserMealUnit mealunit=new UserMealUnit(); 

        return mealunit;


    }

我有UserMealUnit mealunit=new UserMealUnit();部分问题,所以我还没有填写.你可以看到我有布尔类型,整数类型和浮点数,在androidhive示例中所有列类型都是字符串,我无法得到为什么他将它们完全解析为整数类型以及我在代码中与此部分有什么关系？这是androidhive中的一部分

 Contact contact = new Contact(Integer.parseInt(cursor.getString(0)),
            cursor.getString(1), cursor.getString(2));

Answer 1

SQLite 没有本机布尔数据类型.请参阅SQLite的数据类型文档.你可以存储如int值0的false和1为true.试试这样吧

public UserMealUnit getusermealunit(int mealid) {
    SQLiteDatabase db = this.getReadableDatabase();

    String selectQuery = "SELECT  * FROM " + TABLE_USERMEALUNIT + " WHERE "
            + TABLE_USERMEALUNIT_ID + " = " + mealid;

    Log.d(LOG, selectQuery);

    Cursor c = db.rawQuery(selectQuery, null);

    if (c != null)
        c.moveToFirst();

    UserMealUnit mealunit = new UserMealUnit();
    mealunit.setMealid(c.getInt(c.getColumnIndex(KEY_ID)));//KEY_ID key for fetching id
    mealunit.setBreakfast((c.getInt(c.getColumnIndex(KEY_BREAKFAST))));//KEY_BREAKFAST key for fetching isBreakfast
    mealunit.setLunch((c.getInt(c.getColumnIndex(KEY_LUNCH))));//KEY_LUNCH key for fetching isLunch
    mealunit.setVegetables((c.getFloat(c.getColumnIndex(KEY_VEGETABLE))));//KEY_VEGETABLE key for fetching vegetables

    return mealunit;
}

模型类

public class UserMealUnit {

    int mealid;
    int breakfast;
    int lunch;
    float vegetables;

    public int getMealid() {
        return mealid;
    }
    public void setMealid(int mealid) {
        this.mealid = mealid;
    }
    public int getBreakfast() {
        return breakfast;
    }
    public void setBreakfast(int breakfast) {
        this.breakfast = breakfast;
    }
    public int getLunch() {
        return lunch;
    }
    public void setLunch(int lunch) {
        this.lunch = lunch;
    }
    public float getVegetables() {
        return vegetables;
    }
    public void setVegetables(float vegetables) {
        this.vegetables = vegetables;
    }
}

查询创建TABLE_USERMEALUNIT表

private static final String CREATE_TABLE_USERMEALUNIT = "CREATE TABLE "
            + TABLE_USERMEALUNIT + "(" + KEY_ID + " INTEGER PRIMARY KEY," + KEY_BREAKFAST
            + " INTEGER,"+ KEY_LUNCH + " INTEGER," +  KEY_VEGETABLE + " REAL" + ")";

在Activity检查中,lunch或breakfast等于1这样的值

if(lunch == 1) {
   //lunch is int value fetched from db it means true do what ever you want to do
} else {
   //it means false do what ever you want to do
}