java - 在构造函数中保存到数据库

Question

我遇到了问题。我正在构建一个预算应用程序，因此我创建了 2 个名为“年”和“月”的类

当调用 Year 的构造函数时，我想创建 12 个 Month 对象并将它们添加到我的 SQLite 数据库中。

我将数据库类的实例设置为构造函数的参数。

年级:

public class Year implements Serializable {

private int id;
private int year;
private Month[] months;
private List<Category> categories;

public Year(int year, MyDBHandler mdb) {
    this.id = mdb.getYearID();
    this.year = year;
    for(int i = 0; i > 12; i ++){
        Month mon = new Month(mdb.getMonthID(), i, this);
        mdb.addMonth(mon);
        months[i] = mon;
    }
    mdb.close();
}

}

月份类(class):

public class Month implements Serializable{
private int id;
private String name;
private int number;
private Year year;
private List<Entry> entries;
private List<Category> categories;


public Month(int id, int nr, Year year) {
    this.id = id;
    String [] months = {"January", "February", "March", "April", "May", "June", "July", "August", "Septemper", "October", "November", "December"};
    this.name = months[nr];
    this.number = nr;
    this.year = year;
    categories = year.getCategories();
}

}

我的 DbHandler 类中的相关方法

public void addMonth(Month month){
    ContentValues values = new ContentValues();
    values.put(COLUMN_MONTH_ID, month.getId());
    values.put(COLUMN_MONTH_NUMBER, month.getNumber());
    values.put(COLUMN_MONTH_YEAR_ID, month.getYear().getId());
    SQLiteDatabase db = getWritableDatabase();
    db.insert(TABLE_MONTH, null, values);
}

public ArrayList<Month> getMonths() {
    ArrayList<Month> list = new ArrayList<Month>();
    SQLiteDatabase db = getWritableDatabase();
    String query = "SELECT * FROM " + TABLE_MONTH + " WHERE 1";

    Cursor c = db.rawQuery(query, null);
    c.moveToFirst();

    while (!c.isAfterLast()) {
        if (c.getString(c.getColumnIndex(COLUMN_MONTH_NUMBER)) != null) {
            int x1 = c.getInt(c.getColumnIndex("_id"));
            int x2 = c.getInt(c.getColumnIndex("nr"));

            Month month = new Month(x1, x2, null);
            list.add(month);
            c.moveToNext();
        }
    }
    c.close();
    db.close();
    return list;
}

问题是，即使我可以调用创建数据库一年，我的数据库不包含月份

Answer 1

这更适合评论，但因为我没有代表:

for(int i = 0; i > 12; i ++)

应该是

for (int i = 0; i < 12; i++)