类型信息的问题
class Person{
public void say(){
System.out.println("Person");
}
}
class Student extends Person{
@Override
public void say(){
System.out.println("Student");
}
}
public class Pet {
public static void main(String[] args) {
Person p = new Person();
if(p instanceof Person){
((Student)p).say();
}
}
}
请问为什么会抛出ClassCastException
[解决办法]
class Person {
public void say() {
System.out.println("Person");
}
}
class Student extends Person {
@Override
public void say() {
System.out.println("Student");
}
}
public class Pet {
public static void main(String[] args) {
Person p = new Student();
if (p instanceof Person) {
((Student) p).say();
}
}
}
[解决办法]
Person p = new Person();
if(p instanceof Person){
((Student)p).say();
}
==>
Person p = new Student();
if(p instanceof Student){
((Student)p).say();
}
[解决办法]
因为是声明的变量是子类型，你强转成父类型，编译可以通过，但是实际运行的时候不行，像楼上两位这么改即可。
