java班级类拓展 两门成绩 子类小组
作者:互联网
java班级类拓展 两门成绩 子类小组
一、基础性题目
将实验一的学生成绩题目进行扩展,要求:
创建一个班级类的子类,兴趣小组类;
class InGroup extends Class
新增成员变量:兴趣小组名称,活动时间(星期几表示),活动地点;
String groupName;
String activityTime;
String place;
新增成员方法:设置组名,设置活动时间,设置活动地点,显示组名+组员列表+活动时间+活动地点,显示小组平均成绩,最高分,最低分及分数分布统计;
public String getGroupName() {
return groupName;
}
// 使用setter,getter
public void setGroupName(String groupName) {
this.groupName = groupName;
}
重写平均成绩方法(去掉一个最高,去掉一个最低,取平均)。
String getAverage() {
sum[j] = sum[j] - maxScore - minScore;
return sum[j] / (s.length - 2);
}
课程拓展到多门课程。
class Student {
String name;
Grade[] grade;
Student(String name, Grade[] grade) {
this.name = name;
this.grade = grade;
}
}
//课程拓展到多门课程。
class Grade {
int courseNo;
String courseName;
double courseScore;
Grade(int courseNo, String courseName, double courseScore) {
this.courseNo = courseNo;
this.courseName = courseName;
this.courseScore = courseScore;
}
}
classDiagram
综上所述,程序源代码为
class Student {
String name;
Grade[] grade;
Student(String name, Grade[] grade) {
this.name = name;
this.grade = grade;
}
}
//课程拓展到多门课程。
class Grade {
int courseNo;
String courseName;
double courseScore;
Grade(int courseNo, String courseName, double courseScore) {
this.courseNo = courseNo;
this.courseName = courseName;
this.courseScore = courseScore;
}
}
class Class {
Student[] s;
Class(Student[] s) {
this.s = s;
}
String getAverage() {
double[] sum = {0, 0};
for (int j = 0; j < 2; j++) {
for (int i = 0; i < s.length; i++) {
sum[j] += s[i].grade[j].courseScore;
}
}
return "课程号:" + s[0].grade[0].courseNo + " 课程名:" + s[0].grade[0].courseName +
"的平均成绩为:" + sum[0] / s.length +
"\n\t课程号:" + s[0].grade[1].courseNo + " 课程名:" + s[0].grade[1].courseName +
"的平均成绩为:" + sum[1] / s.length;
}
String getMax() {
double[] maxScore = {0, 0};
for (int j = 0; j < 2; j++) {
for (int i = 0; i < s.length; i++) {
if (s[i].grade[0].courseScore > maxScore[j]) {
maxScore[j] = s[i].grade[j].courseScore;
}
}
}
return "课程号:" + s[0].grade[0].courseNo + " 课程名:" + s[0].grade[0].courseName +
"的最高分:" + maxScore[0] +
"\n\t课程号:" + s[0].grade[1].courseNo + " 课程名:" + s[0].grade[1].courseName +
"的最高分:" + maxScore[1];
}
public String getMin() {
double[] minScore = {100, 100};
for (int j = 0; j < 2; j++) {
for (int i = 0; i < s.length; i++) {
if (s[i].grade[1].courseScore < minScore[0]) {
minScore[0] = s[i].grade[j].courseScore;
}
}
}
return "课程号:" + s[0].grade[0].courseNo + " 课程名:" + s[0].grade[0].courseName +
"的最高分:" + minScore[0] +
"\n\t课程号:" + s[0].grade[1].courseNo + " 课程名:" + s[0].grade[1].courseName +
"的最高分:" + minScore[1];
}
String gradeDistribution() {
int[] excellence = {0, 0};
int[] good = {0, 0};
int[] pass = {0, 0};
int[] failure = {0, 0};
for (int j = 0; j < 2; j++) {
for (int i = 0; i < s.length; i++) {
int grade = (int) (s[i].grade[j].courseScore / 10);
switch (grade) {
case 10:
case 9:
excellence[j]++;
break;
case 8:
case 7:
good[j]++;
break;
case 6:
pass[j]++;
break;
default:
failure[j]++;
break;
}
}
}
return "课程号:" + s[0].grade[0].courseNo + " 课程名:" + s[0].grade[0].courseName +
"分数分布——优秀:" + excellence[0] + " 良好:" + good[0] + " 及格:" + pass[0] + " 不及格:" + failure[0] +
"\n\t课程号:" + s[0].grade[1].courseNo + " 课程名:" + s[0].grade[1].courseName +
"分数分布——优秀:" + excellence[1] + " 良好:" + good[1] + " 及格:" + pass[1] + " 不及格:" + failure[1];
}
}
class InGroup extends Class {
String groupName;
String activityTime;
String place;
InGroup(Student[] s) {
super(s);
}
public String getGroupName() {
return groupName;
}
public void setGroupName(String groupName) {
this.groupName = groupName;
}
public String getActivityTime() {
return activityTime;
}
public void setActivityTime(String activityTime) {
this.activityTime = activityTime;
}
public String getPlace() {
return place;
}
public void setPlace(String place) {
this.place = place;
}
// 重写平均成绩方法(去掉一个最高,去掉一个最低,取平均)。
@Override
String getAverage() {
double[] sum = {0, 0};
for (int j = 0; j < 2; j++) {
for (int i = 0; i < s.length; i++) {
sum[j] += s[i].grade[j].courseScore;
}
double maxScore = 0;
for (int i = 0; i < s.length; i++) {
if (s[i].grade[0].courseScore > maxScore) {
maxScore = s[i].grade[j].courseScore;
}
}
double minScore = 100;
for (int i = 0; i < s.length; i++) {
if (s[i].grade[0].courseScore > minScore) {
minScore = s[i].grade[j].courseScore;
}
}
sum[j] = sum[j] - maxScore - minScore;
}
return "课程号:" + s[0].grade[0].courseNo + " 课程名:" + s[0].grade[0].courseName +
"的平均成绩为:" + sum[0] / (s.length - 2) +
"\n\t课程号:" + s[0].grade[1].courseNo + " 课程名:" + s[0].grade[1].courseName +
"的平均成绩为:" + sum[1] / (s.length - 2);
}
String memberlist() {
StringBuilder namelist = new StringBuilder(" 小组成员:");
for (Student i : s) {
namelist.append(i.name + ' ');
}
String menmberList = namelist.toString();
return menmberList;
}
String showDetails() {
return "组名:" + groupName + memberlist() + "\n\t活动时间:" + activityTime +
" 活动地点:" + place;
}
String showGrade() {
return "小组平均成绩:" + getAverage() + "\n最高分:" + getMax() +
"\n最低分:" + getMin() + "\n分数分布统计:" + gradeDistribution();
}
}
public class E2T1 {
public static void main(String[] args) {
int stuNum = 4;
String[] name = {"wei", "zhao", "wang", "zhang"};
int courseNum = 2;
int[] courseNo = {1, 2};
String courseName[] = {"Chinese", "Math"};
double[][] courseScore = {{100, 90}, {81, 79}, {69, 86}, {81, 72}};
Student[] stu = new Student[stuNum];
for (int i = 0; i < stuNum; i++) {
Grade grade[] = new Grade[courseNum];
for (int j = 0; j < courseNum; j++) {
grade[j] = new Grade(courseNo[j], courseName[j], courseScore[i][j]);
}
stu[i] = new Student(name[i], grade);
}
InGroup g = new InGroup(stu);
g.setGroupName("第一组");
g.setActivityTime("周五");
g.setPlace("图书馆");
System.out.println("小组详情:\n" + g.showDetails());
System.out.println("\n小组成绩:\n" + g.showGrade());
}
}
小组详情:
组名:第一组 小组成员:wei zhao wang zhang
活动时间:周五 活动地点:图书馆
小组成绩:
小组平均成绩:课程号:1 课程名:Chinese的平均成绩为:65.5
课程号:2 课程名:Math的平均成绩为:68.5
最高分:课程号:1 课程名:Chinese的最高分:100.0
课程号:2 课程名:Math的最高分:90.0
最低分:课程号:1 课程名:Chinese的最高分:72.0
课程号:2 课程名:Math的最高分:100.0
分数分布统计:课程号:1 课程名:Chinese分数分布——优秀:1 良好:2 及格:1 不及格:0
课程号:2 课程名:Math分数分布——优秀:1 良好:3 及格:0 不及格:0
二、开放性题目(反编译)
class Circle {
double r;
Circle(double r) {
this.r = r;
}
double getArea() {
return Math.PI * r * r;
}
}
public class E2T2 {
public static void main(String[] args) {
Circle c = new Circle(1.0);
System.out.println(c);
}
}
程序直接打印对象c,输出的结果是其所属类名@地址。
(1)请通过反编译工具,找出原因。
提示:所有的Java类都继承于java.lang.Object。
通过反编译工具反编译E2T2.class,Cricle.class。得到如下代码
class Circle {
double r;
Circle(double paramDouble) {
this.r = paramDouble;
}
double getArea() {
return Math.PI * this.r * this.r;
}
}
public class E2T2 {
public static void main(String[] paramArrayOfString) {
Circle circle = new Circle(1.0D);
System.out.println(circle);
}
}
使用了String[] paramArrayOfString做默认参数,而传入数据则是double 1.0,顾需要使用toString转格式
查阅java.lang.Object源代码,发现其中的toString()方法
public String toString() {
return getClass().getName() + "@" + Integer.toHexString(hashCode());
}
程序应该是调用父类的toString()完成的输出
(2)修改程序,让它打印对象c时,输出Circle类的对象c的面积吗?且保留2位小数。
已经知道程序的输出所调用的方法后,我们可以重写toString()方法完成输出,再使用String.format()保留小数
class Circle {
double r;
Circle(double r) {
this.r = r;
}
String getArea() {
return String.format("%.2f", Math.PI * r * r);
}
@Override //重写的方法
public String toString() {
return getClass().getName() + "@" + Integer.toHexString(hashCode()) +"\n圆的面积为:"+ getArea();
}
}
public class E2T2 {
public static void main(String[] args) {
Circle c = new Circle(1.0);
System.out.println(c);
}
}
程序输出结果为:
Circle@1b6d3586
圆的面积为:3.14
标签:java,String,两门,grade,子类,courseName,courseScore,int,课程 来源: https://blog.csdn.net/m0_46530662/article/details/118614695