建设工程查询网站,网站开发 实名认证需要备案吗,四川航霖企业管理咨询有限公司,企业网站开发期末报告1#xff1a;关于多态描述错误的是(D)
A. 父类型的引用指向不同的子类对象
B. 用引用调用方法#xff0c;只能调用引用中声明的方法
C. 如果子类覆盖了父类中方法#xff0c;则调用子类覆盖后的方法
D. 子类对象类型会随着引用类型的改变而改变 2#xff1a;class Supe…1关于多态描述错误的是(D)
A. 父类型的引用指向不同的子类对象
B. 用引用调用方法只能调用引用中声明的方法
C. 如果子类覆盖了父类中方法则调用子类覆盖后的方法
D. 子类对象类型会随着引用类型的改变而改变 2class Super{
public void m1(){}
public void m2(){} } class Sub extends Super{
public void m2(){}
public void m3(){}
public void m4(){} } 创建对象Super snew Sub();用s引用可以调用的方法(A B)
A.m1() B. m2() C. m3() D. m4() 3class Super{}
class Sub extends Super{}
class ClassA extends Super{}
public class TestSuper{
public static void main(String[] args){
//1
}
}
对于1处代码及对其描述错误的是(CD)
A. Super snew Sub(); B. Sub snew Sub(); Super sups; C. Super snew Sub(); Sub s2s; 强转 D. Super snew Sub(); ClassA c(ClassA)s; 4:class Super{
public int getLength(){
return 4;
} }
class Sub extends Super{
public long getLength(){
return 5;
}
}
public class Test{
public static void main(String[] args){
Super s1new Super();
Super s2new Sub();
System.out.println(s1.getLength()\ts2.getLenght());
}
}
以上程序输出的结果是(D)
4 4 B. 4 5 C.5 5 D.编译报错 父类不能调用子类独有方法 5:完成(1、2、3、4、5)处代码要求将完整题目抄写 1public Animal(){}
public Anamal(String name){
this.namename;
}
2:public String getName(){
return name;
}
public void setName(String name){
this.namename;
} 3:public Dog(){} public Dog(String name){
this.namename;} 4:Animal[] animal{new Dog,new Cat,new Dog,new Cat} int count0;
for(int i0;ianimal.length;i){
if(animal[i]instanceof new Dog){
count;
}
}
System.out.println(count);
} 6:(多态)仔细阅读以下代码编译是否通过如果通过写出输出结果如果不能通过则如何修改 不能通过
Sub sub(Sub)s;
sub.method(“Hello”); 7:(多态)仔细阅读以下代码写出程序运行之后输出的结果。 method() in sub
method() in super 8:(多态)仔细阅读以下代码下列几个选项中有哪几个放在//1 位置能够编译通过() return null; return new Animal();return new Dog();return new Cat(); 9:(多态)在继承题目的基础上定义一个 Person 类型的数组存储多个不同类型的子类 型对象
(1) 统计并打印输出数组中所有学生干部的个数
(2) 打印输出所有学生的信息
package com.by.homework4.person;public class Person {private String name;private String sex;private int age;private String nationality;public Person() {}public Person(String name, String sex, int age, String nationality) {this.name name;this.sex sex;this.age age;this.nationality nationality;}public String getName() {return name;}public void setName(String name) {this.name name;}public String getSex() {return sex;}public void setSex(String sex) {this.sex sex;}public int getAge() {return age;}public void setAge(int age) {this.age age;}public String getNationality() {return nationality;}public void setNationality(String nationality) {this.nationality nationality;}public void eat(){System.out.println(人的吃饭方法);}public void sleep(){System.out.println(人的睡觉方法);}public void work(){System.out.println(人的工作方法);}
}package com.by.homework4.person;public class Student extends Person {private String school;private String schoolNum;public Student(){}public Student(String school, String schoolNum) {this.school school;this.schoolNum schoolNum;}public Student(String name, String sex, int age, String nationality, String school, String schoolNum) {super(name, sex, age, nationality);this.school school;this.schoolNum schoolNum;}public String getSchool() {return school;}public void setSchool(String school) {this.school school;}public String getSchoolNum() {return schoolNum;}public void setSchoolNum(String schoolNum) {this.schoolNum schoolNum;}public void work(){System.out.println(学生的学习方法);}
}package com.by.homework4.person;public class StudentLead extends Student {private String zhiwu;public StudentLead(){}public StudentLead(String zhiwu) {this.zhiwu zhiwu;}public StudentLead(String school, String schoolNum, String zhiwu) {super(school, schoolNum);this.zhiwu zhiwu;}public StudentLead(String name, String sex, int age, String nationality, String school, String schoolNum, String zhiwu) {super(name, sex, age, nationality, school, schoolNum);this.zhiwu zhiwu;}public String getZhiwu() {return zhiwu;}public void setZhiwu(String zhiwu) {this.zhiwu zhiwu;}public void kaihui(){System.out.println(学生的开会方法);}
}package com.by.homework4.person;public class Test {public static void main(String[]args){Person []person{new Student(张yi,男,18,中国,一中,123),new Student(张er,男,18,中国,一中,123),new Student(张三,男,18,中国,一中,123),new Student(张si,男,18,中国,一中,123),new Student(张wu,男,18,中国,一中,123),new Student(张liu,男,18,中国,一中,123)};for(int i0;i person.length;i){Student students(Student) person[i];System.out.println(students.getName()students.getSex()students.getAge()students.getNationality()students.getSchool()students.getSchoolNum());}Student []student{new StudentLead(张yi,男,18,中国,一中,123,团长),new StudentLead(张二,男,18,中国,一中,123,团长),new StudentLead(张三,男,18,中国,一中,123,团长),new StudentLead(张四,男,18,中国,一中,123,团长),new StudentLead(张五,男,18,中国,一中,123,团长),new StudentLead(张六,男,18,中国,一中,123,团长)};for(int i0;istudent.length;i){StudentLead studentLead(StudentLead)student[i];System.out.println(studentLead.getName()studentLead.getSex()studentLead.getAge()studentLead.getNationality()studentLead.getSchool()studentLead.getSchoolNum()studentLead.getZhiwu());}}
} 10:编程在继承题目的基础上创建一个长度为 3 的数组里面有三个不同类型的对象 分别打印这三个圆形、矩形、正方形的周长和面积。 11:编程阅读以下代码根据要求完成程序功能 (1) 在程序的 1、2、3 处填上适当的 构造方法或 get/set 方法
(2) 完成 4 处的填空getAllDog 方法从一个 Animal 数组中挑选出所有的 Dog 对象并把这
些对象放在一个 Dog 数组中返回 12:编程在在继承题目的基础上创建一个 Employee 数组分别创建若干不同的 Employee 对象并打印某个月的工资。
