Java 在sqlite android中从表中获取单行

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 我阅读并试图像编写示例代码一样编写代码，但当我想编写“获取单行”部分时，我会遇到一些问题

这是我的模型课

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;
}

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;
    }
}

这是我的数据库适配器代码

获取单行

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;


    }

我在

UserMealUnit-mealunit=newusermealunit（）中遇到问题部分，所以我还没有填充它。
正如你们所看到的，我有布尔型，整数型，还有浮点型，在androidhive示例中，所有列类型都是字符串，我无法理解他为什么要将它们解析为整数型，以及我在代码中对这部分做了什么？
这是androidhive中的角色

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

SQLite没有本机布尔数据类型。请注意，您可以存储int值，如
0
表示
false
和
1
表示
true
。
像这样试试

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;
}

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
}

模型类

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;
}

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;
    }
}

用于创建
表\u USERMEALUNIT
表的查询

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
活动中
检查
午餐
或
早餐
的值是否等于
1
，如下所示

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;
}

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
}

嗨，咪咪，光标。getString（0）是键ID，光标。getString（1）是键名称和光标。getString（2）是键ID，在联系人表中没有字段，因为布尔类型，如果我添加它会出错=0
mealunit.setBreakfast（（c.getInt（c.getColumnIndex（KEY_早餐）））！=0？SQLite数据库中没有布尔类型。相反，我必须将0保存为false，将1保存为true。所以要读取你的值，这里的键是布尔的，但我们有getInt，我用的是getInt类型=0来解决这个问题。@mimi:是的，为
表创建表后查询\u USERMEALUNIT
@mimi检查编辑后的答案这就是我想说的让我们来看看。