在（android）領域我如何根據列乘以列來對列表進行排序？

Question

我得到了一個境界的對象，像這樣

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

public class Product extends RealmObject { 
public double price; 
} 

我想通過MyItem（product.price *量）上升排序我的境界名單。 Realm如何實現這一點？

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; 
    } 
} 

然後

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

---

編輯：有了修改，適用同樣的規則。

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(); 
      } 
     } 
    } 
} 

然後

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