通过集合排序获取子类参数

Question

问题：

1) 我想做collection.sort。问题出在“public int compareTo（Fruit other）”内部，我想按字母顺序对味道和气味进行排序，但是，我不知道如何将子类值传递给超类并使用“this & other”比较.感谢帮助

PS：代码简化了，只想知道子类参数的排序方式。

代码如下：

public class Fruit implements Comparable<Fruit>{

protected String Type;
protected int price;

public Fruit(String Type , int Price)
{
    this.Type = Type;
    this.price = Price;

}
public int compareTo (Fruit other)
{
    if (this.Type.compareTo(other.Type) != 0)
    {
        return (this.Type.compareTo(other.Type));
    }
    else if (Integer.compare(this.price,  other.price)!=0)
    {
        return (Integer.compare(this.price,  other.price));
    }
    //else if (  ** If price is same , then get sorting with taste 
    in  alphabetical order **) //
    {
    }
    //else if (  ** if taste is the same , then get sorting with smell
    in alphabetical order **) //
    {
    }
    else 
    {
        return 0;
    }
}




 public class orange extends Fruit()
 { 
 private String taste;
 private String smell; 
 public orange (String Type , int Price , String taste , String smell)
 {
    super (Type, Price);
    this.taste = taste;
    this.smell = smell;
 }

 } 

Answer 1

测试 compareTo 中的类：

• 如果它是你的子类

• 还有另一个对象

• 投射它们，并与您的子测试进行比较

假设：

public class Kiwi extends Fruit 
   {
   public String taste;  // public for demo
   public String smell;
   }

测试和演员：

Fruit one_fruit;  // this or other
if (one_fruit instanceof Kiwi) 
    {
    Kiwi really_kiwi= (Kiwi) one_fruit; // CAST THERE !
    if (really_kiwi.taste ...) // You can then use taste and smell ...