Select distinct
i.Postcode
, i.Number
, case when i.[rank] = 1 then i.Occupant end as [First Tennant]
, case when i.[rank] = 2 then i.Occupant end as [Second Tennant]
, case when i.[rank] = 3 then i.Occupant end as [Third Tennant]
, case when i.[rank] = 4 then i.Occupant end as [Fourth Tennant]
, case when i.[rank] = 5 then i.Occupant end as [Fifth Tennant]
from Reporting.dbo.Test u
inner join RANKING i on i.Postcode = u.Postcode
我不知道为什么Postcode | Number | First Tennant | Second Tennant | Third Tennant | Fourth Tennant | Fifth Tennant |
AA001AA | 12 | D | NULL | NULL | NULL | NULL |
AA001AA | 12 | NULL | E | NULL | NULL | NULL |
无法找到package finalpaperpractice;
public class PolymorphicTest {
public void function(){
System.out.println("1");
}
public static void main (String [] args){
Object obj [] = {new PolymorphicTest(), new A(), new B()};
for (int i = 0; i < 3; i ++){
obj[i].function(); // error on this line
}
}
}
class A{
public void function(){
System.out.println("2");
}
}
class B{
public void function(){
System.out.println("3");
}
}
。
我编写了一个覆盖obj[i]的代码，该代码完美无缺，但这段代码并没有覆盖。
答案 0 :(得分：2)
因为obj是Object类型且Object类没有声明function方法。
您可以使用function方法创建一个接口，并在所有类中的function方法中实现此接口。
然后，
Object obj
应该改为
<Your Interface> obj