从数据库内容填充微调器 (SQLite)

Question

如何从数据库 (SQLite) 填充微调器内容

我有 POJO：类别，包含 id 和 name， 我已经有了这个表，它有一个函数可以像这样获取 ArrayList：

public List<SetcardCategory> getAllSetcardCategory()
{
    List<SetcardCategory> setcardCategories = new ArrayList<SetcardCategory>();
    String selectQuery = "SELECT  * FROM " + TABLE_SETCARD_CATEGORIES;

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

    // looping through all rows and adding to list
    if (c.moveToFirst()) {
        do {
            SetcardCategory setcardCategory = new SetcardCategory();
            setcardCategory.setId(c.getInt((c.getColumnIndex("id"))));
            setcardCategory.setName(c.getString(c.getColumnIndex("name")));

            // adding to tags list
            setcardCategories.add(setcardCategory);
        } while (c.moveToNext());
    }
    return setcardCategories;
}

然后在 Activity 我这样称呼它：

List<SetcardCategory> setcardCategories = db.getAllSetcardCategory();
    ArrayAdapter<SetcardCategory> arrayAdapter = new ArrayAdapter<SetcardCategory>(
            this, android.R.layout.simple_spinner_item, setcardCategories);
    arrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    Spinner sItems = (Spinner) findViewById(R.id.setcardCategory);
    sItems.setAdapter(arrayAdapter);

当我运行它时，它会加载这样的字符串：“schema.SetcardCategory@22293c98”和许多其他类似的值。

如何填充微调器以将 name 字段显示为标签，并将 id 字段显示为我们提取以保存到 DB 中的值？

Answer 1

class Pojo{
 private String name;
  @Override
    public String toString() {
        return name;
    }
}

在 pojo 类中这样做，这样当它使用适配器中的 to string 方法来加载数据时，它将为对象返回一个值

Answer 2

解决方案 1 覆盖 SetcardCategory 类中的 toString 方法

class SetcardCategory {
...
...
@Override
    public String toString() {
        return this.name;
    }
}

解决方案 2 如果您只想显示名称，只需从 DB 中选择名称即可

public List<String> getAllSetcardCategory()
    {
        List<String> setcardCategories = new ArrayList<String>();
        String selectQuery = "SELECT  * FROM " + TABLE_SETCARD_CATEGORIES;

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

        // looping through all rows and adding to list
        if (c.moveToFirst()) {
            do {
                // adding to tags list
                setcardCategories.add(c.getString(c.getColumnIndex("name")));
            } while (c.moveToNext());
        }
        return setcardCategories;
    }

并创建 Array Adapter 为

List<String> setcardCategories = db.getAllSetcardCategory();
    ArrayAdapter<SetcardCategory> arrayAdapter = new ArrayAdapter<SetcardCategory>(
            this, android.R.layout.simple_spinner_item, setcardCategories);
    arrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);