instanceof和Object 的两个问题
class Groundhog2 {
int ghNumber;
Groundhog2(int n) { ghNumber = n; }
public int hashCode() { return ghNumber; }
public boolean equals(Object o) {
return (o instanceof Groundhog2)
&& (ghNumber == ((Groundhog2)o).ghNumber);//
}
}
instanceof是做什么用的??什么时候能用到它?
&& (ghNumber == ((Groundhog2)o).ghNumber);//这一行的Groundhog2)o).ghNumber);是怎么回事???o被我定义成Object 了,怎么还有转型?然后在调用ghNumber?