- 学生类（Student）:属性：姓名、年龄、数学成绩、英语成绩；方法：构造函数（初始化姓名和年龄），设置成绩，求均分；子类（Newstudent）:属性：政治成绩；方法：构造函数，设置成绩（与父类的设置成绩构成重载），求均分；在main函数中定义子类的对象，调用其所有方法；
public class Test14 {
public static void main(String[] args) {
NewStudent a = new NewStudent("Zhang", 20);
a.setGrade(45, 35, 77);
System.out.println(a.getAvg());
}
}
class Student {
String name;
int age;
float mathGrade;
float engGrade;
Student(String name, int age) {
this.name = name;
this.age = age;
}
void setGrade(float mathGrade, float engGrade) {
this.mathGrade = mathGrade;
this.engGrade = engGrade;
}
float getAvg() {
return (mathGrade + engGrade) / 2;
}
}
class NewStudent extends Student {
float polGrade;
NewStudent(String name, int age) {
super(name, age);
}
void setGrade(float mathGrade, float engGrade, float polGrade) {
this.mathGrade = mathGrade;
this.engGrade = engGrade;
this.polGrade = polGrade;
}
float getAvg() {
return (mathGrade + engGrade + polGrade) / 3;
}
}
- 日期（Date）：属性：年，月，日；方法：设置日期，输出日期；子类（NewDate）：属性：时，秒，分；方法：设置日期（和父类构成重载），输出日期（和父类构成重写，但是要调用父类的输出日期函数）；在main函数中定义子类的对象，调用其所有方法；
public class Test15 {
public static void main(String[] args) {
NewDate a = new NewDate();
a.setDate(2020, 10, 19, 9, 40, 0);
a.outputDate();
}
}
class Date {
int year;
int month;
int day;
void setDate(int year, int month, int day) {
this.year = year;
this.month = month;
this.day = day;
}
void outputDate() {
System.out.printf("%d年%d月%d日", year, month, day);
}
}
class NewDate extends Date {
int hour;
int second;
int minute;
void setDate(int year, int month, int day, int hour, int minute, int second) {
this.year = year;
this.month = month;
this.day = day;
this.hour = hour;
this.second = second;
this.minute = minute;
}
void outputDate() {
super.outputDate();
System.out.printf("%d时%d分%d秒", hour, minute, second);
}
}
- 父类（Data）：属性：int a, 方法：求绝对值，求阶乘；子类（Newdata）:属性 int n, 方法：求1-n的绝对值和，求1-n的阶乘和；在main函数中定义子类的对象，调用其所有方法；
public class Test16 {
public static void main(String[] args) {
NewData a = new NewData();
a.n = 2;
System.out.println(a.getA());
System.out.println(a.getFactorial());
}
}
class Data {
int a;
int getA() {
if (a < 0) return -a;
else return a;
}
int getFactorial() {
int result = 1;
if (a == 0) return 1;
else {
for (int i = 1; i <= a; ++i) {
result *= i;
}
}
return -1;
}
}
class NewData extends Data {
int n;
int getA() {
int result = 0;
int m = n;
if (n < 0) m = -n;
for (int i = 1; i <= m; ++i) {
result += i;
}
return result;
}
int getFactorial() {
int result = 0;
if (n < 0) return -1;
for (int i = 1; i <= n; ++i) {
int temp = 1;
for (int j = 1; j <= i; ++j) {
temp *= j;
}
result += temp;
}
return result;
}
}
- 父类（Employee）：属性：姓名、工号、工资；方法：构造函数（初始化姓名、工号），设置工资，输出信息（姓名，工号，工资）；输出等级（工资>5000, 为C，否则为D）；子类（Leader）：属性：等级；方法：设置等级，输出信息（姓名，工号，等级和工资），计算工资（等级为A的，工资+5000；等级为B的，工资增加2000）；在main函数中定义子类的对象，调用其所有方法；
public class Test17 {
public static void main(String[] args) {
Leader a = new Leader("Zhang", 123);
a.setPay(5000);
a.setLevel('A');
a.outputInf();
a.calPay();
}
}
class Employee {
String name;
int id;
float pay;
Employee(String name, int id) {
this.id = id;
this.name = name;
}
void setPay(float pay) {
this.pay = pay;
}
void outputInf() {
System.out.printf("姓名：%s 工号：%d 工资：%f", name, id, pay);
}
void outputLevel() {
if (pay > 5000) System.out.println('C');
else System.out.println('D');
}
}
class Leader extends Employee {
char level;
Leader(String name, int id) {
super(name, id);
}
void setLevel(char level) {
this.level = level;
}
void outputInf() {
System.out.printf("姓名：%s 工号：%d 等级：%c 工资：%f", name, id, level, pay);
}
void calPay() {
if (level == 'A') pay += 5000;
if (level == 'B') pay += 2000;
}
}