Question

我有一个包含查询结果的游标，该查询返回一个SQLite数据库中的成分名称列表及其相应的度量。

我正在尝试实现一个函数，当按下按钮时，该函数将从另一个表中扣除这些值。

我在尝试使用游标值实现此功能时遇到了一些麻烦。我可以将光标传递给函数，还是应该将光标放入列表中，然后将列表变量传递给函数？

以下是我到目前为止的代码，但是如果有人能够指出我的方向会很好。

光标

   final Cursor ingredients = adapter.getRecipesIngredients(recipeCode);

getRecipeIngredients功能

public Cursor getRecipesIngredients(int code)
{
    return db.rawQuery("select _id, ingredient_name, measurement from ingredients where recipe_code = " + code, null);

}

带功能的按键代码

    Button cookButton = (Button) findViewById(R.id.cookButton);
    cookButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            while (ingredients.moveToNext())
            {
                String ingredient = ingredients.getString(0);
                String measurement = ingredients.getString(1);
                int i = Integer.parseInt(measurement);
                adapter.deductIngredient(ingredient, i);
            }
        }
    });

更新表的SQL函数

//deducting ingredients after cooking
public boolean deductIngredient(String ingredient, int measurement)
{
    db.rawQuery("update kitchen set kitchen.measurement = kitchen.measurement - "+measurement+" where kitchen.ingredient_name = "+ingredient, null);
    return true;
}

Answer 1

您的光标包含“成分对象”的数据。游标中的数据按照执行查询的表的列顺序进行组织。您可以使用包含ingredient_name和measurment的列的索引号。像这样举例如：

cursor.moveToFirst();
ArrayList<Ingredient> ingredientList = new ArrayList<Ingredient>;
while(cursor.moveToNext())
{
   Ingredient ingredient = new Ingredient() ;

   ingredient.setName(cursor.getString([index of the column]));
   ingredient.setMeasurement(cursor.getInt([index of the column]);

   ingredientList.add(ingredient);
}

Answer 2

尝试从光标中获取值并传递它们，而不是传递光标对象本身。像这样：

Button cookButton = (Button) findViewById(R.id.cookButton);
cookButton.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        while (ingredients.moveToNext())
        {
            String ingredient = ingredients.getString(ingredients.getColumnIndex("ingredient_name"));
            //If you are storing measurement as int
            int measurement = ingredients.getInt(ingredients.getColumnIndex("measurement"));
            //If you are storing measurement as varchar
            //int measurement = Integer.parseInt(ingredients.getString(ingredients.getColumnIndex("measurement")));
            adapter.deductIngredient(ingredient, measurement);
        }
    }
});

使用Cursor从SQLite中减去值

2 个答案: