Question

我有一个像这样的领域对象

public class MyItem extends RealmObject {
public Product product;
public double amount;
}

public class Product extends RealmObject {
public double price;
}

我想按MyItem（product.price * amount）升序排序我的领域列表。 Realm如何实现这一目标？

Answer 1

public class MyItem extends RealmObject {
    private double price;
    private double amount;
    private double total;

    // getters for price/amount

    public void setPrice(double price) {
        this.price = price;
        this.total = price * amount;
    }

    public void setAmount(double amount) {
        this.amount = amount;
        this.total = price * amount;
    }
}

然后

realm.where(MyItem.class).findAllSorted("total", Sort.ASCENDING);

编辑：通过修改，适用相同的规则。

public class MyItem extends RealmObject {
    private Product product;
    private double amount;

    private double totalPrice;

    void updateTotalPrice() {
        if(product == null) {
            totalPrice = 0;
        } else {
            totalPrice = amount * product.getPrice();
        }
    }

    public void setProduct(Product product) {
        this.product = product;
        updateTotalPrice();
    }

    public void setAmount(double amount) {
        this.amount = amount;
        updateTotalPrice();
    }
}

public class Product extends RealmObject {
    private double price;

    @LinkingObjects("product")
    private final RealmResults<MyItem> items = null;

    public void setPrice(double price) {
        this.price = price;
        if(items != null) { // updates to existing object should happen only via managed objects!
            for(MyItem item : items) {
                item.updateTotalPrice();
            }
        }
    }
}

然后

realm.where(MyItem.class).findAllSorted("totalPrice", Sort.ASCENDING);

在（android）领域我如何根据列乘法对列表进行排序？

1 个答案: