// 父类publicclassPeople{}//子类publicclassManextendsPeople{}//测试类publicclassTest{publicstaticvoidmain(String [] args)throws Exception {correctDown();errorDown();}staticvoidcorrectDown(){
People people=newMan();
System.out.println((Man) people);}//类型转换错误,java.lang.ClassCastException: People cannot be cast to ManstaticvoiderrorDown(){
People people=newPeople();
System.out.println((Man) people);}}