是否偶数
public static boolean isOdd(int data){
if(data%2==0)
return true;
else
return false;
}
创建一个直角三角形类实现IShape接口
class RTriangle implements IShape{
double a,b;
public RTriangle(double a, double b) {
super();
this.a = a;
this.b = b;
}
public double getArea() {
return 0.5*a*b;
}
public double getPerimeter() {
return a+b+Math.sqrt(a*a+b*b);
}
}
判断一个数列是否已排好序
public static boolean isSorted(int[] list)
{
if(list[0]==1) return true;
for (int i=1;i {
if (list[i]>list[i+1])
{
return false;
}
}
return true;
}
编写Matrix类,使用二维数组实现矩阵,实现两个矩阵的乘法。
class Matrix
{
int row, column;
int[][] matrix;
static Scanner reader = new Scanner(System.in);
public static Matrix inputMatrix()
{
int i, j;
Matrix a = new Matrix();
a.row = reader.nextInt();
a.column = reader.nextInt();
a.matrix = new int[a.row][a.column];
for(i = 0 ; i < a.row; i ++)
{
for( j = 0 ; j < a.column ; j ++)
{
a.matrix[i][j] = reader.nextInt();
}
}
return a;
}
public Matrix multiply(Matrix mat)
{
int i, j, k;
Matrix c = new Matrix();
c.row = this.matrix.length;
c.column = mat.matrix[0].length;
c.matrix = new int[c.row][c.column];
for ( i = 0; i < c.row; i ++ )
{
for ( j = 0; j < c.column; j ++ )
{
for( k = 0; k < mat.matrix.length; k ++)
{
c.matrix[i][j] += this.matrix[i][k] * mat.matrix[k][j];
}
}
}
return c;
}
}
jmu-Java-03面向对象基础-覆盖与equals
public boolean equals(Object obj) {
if(this == obj)
return true;
if(obj == null)
return false;
if(!super.equals(obj))
return false;
DecimalFormat df = new DecimalFormat("#.##");
Employee other = (Employee) obj;
if(company == null&&other.company == null)
return df.format(salary).equals(df.format(other.salary));
else if(company == null || other.company == null)
return false;
return company.equals(other.company)
&& df.format(salary).equals(df.format(other.salary));
}
图书和音像租赁
class Media {
String name;
double dailyRent;
void getDailyRent() {
}
}
class Book extends Media {
double price;
Book(String name,double price){
this.name=name;
this.price=price;
getDailyRent();
}
void getDailyRent() {
this.dailyRent=price*0.01;
}
}
class DVD extends Media {
DVD(String name){
this.name=name;
getDailyRent();
}
void getDailyRent() {
dailyRent=1;
}
}
class MediaShop {
static double calculateRent(Media[] medias, int days) {
int i;
double rent=0;
for(i=0;i
rent=rent+medias[i].dailyRent;
}
return rent*days;
}
}
设计门票(抽象类)
abstract class Ticket {
int number;
public Ticket(int number){
this.number = number;
}
abstract public int getPrice();
abstract public String toString();
}
class WalkupTicket extends Ticket {
int price;
public WalkupTicket(int number){
super(number);
this.price = 50;
}
public int getPrice(){
return this.price;
}
public String toString(){
return "Number:" + this.number + ",Price:" + this.price;
}
}
class AdvanceTicket extends Ticket {
int leadTime;
int price;
AdvanceTicket(int number,int leadTime){
super(number);
this.leadTime=leadTime;
if(leadTime>10)
this.price = 30;
else
this.price = 40;
}
public int getPrice(){
return this.price;
}
public String toString(){
return "Number:"+this.number+",Price:"+this.price;
}
}
class StudentAdvanceTicket extends AdvanceTicket {
int height;
int price;
public StudentAdvanceTicket(int number,int leadTime,int height) {
super(number,leadTime);
this.height=height;
if(height>120) {
if(leadTime>10)this.price=20;
else this.price=30;
}else {
if(leadTime>10)this.price=10;
else this.price=15;
}
}
public int getPrice() {
return this.price;
}
public String toString() {
return "Number:"+this.number+",Price:"+this.price;
}
}
TDVector
public TDVector()
{
x = 0;
y = 0;
}
public TDVector(double x, double y)
{
this.x = x;
this.y = y;
}
public TDVector(TDVector b)
{
this.x = b.x;
this.y = b.y;
}
public TDVector add(TDVector c)
{
TDVector a = new TDVector();
a.x = this.x + c.x;
a.y = this.y + c.y;
return a;
}
public void setY(double y)
{
this.y = y;
}
public void setX(double x)
{
this.x = x;
}
public double getX()
{
return x;
}
public double getY()
{
return y;
}
Book类的设计
class Book
{
private String id;
private int price;
private String ren;
private int year;
public Book(String id,int price,String ren,int year)
{
this.id = id;
this.price = price;
this.ren = ren;
this.year = year;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public int getPrice() {
return price;
}
public void setPrice(int price) {
this.price = price;
}
public String getRen() {
return ren;
}
public void setRen(String ren) {
this.ren = ren;
}
public int getYear() {
return year;
}
public void setYear(int year) {
this.year = year;
}
}
模拟题: 重写父类方法equals
public boolean equals(Object ps)
{
Point p = (Point) ps;
return (this.xPos == p.xPos && this.yPos == p.yPos);
}
jmu-Java-03面向对象基础-Object
java.util.List
jmu-Java-06异常-finally
System.out.println("resource open success");
} catch (Exception e) {
System.out.println(e);
} finally {
try {
resource.close();
System.out.println("resource release success");
} catch (RuntimeException e) {
System.out.println(e);
}
}
租车服务
abstract class Vehicle{
abstract double getMoney();
}
class Truck extends Vehicle{
double load;
public Truck(double load) {
this.load=load;
}
public double getMoney() {
return 1000*this.load;
}
}
class Keche extends Vehicle{
int seat;
public Keche(int seat) {
this.seat=seat;
}
public double getMoney() {
return 50*this.seat;
}
}
class Car extends Vehicle{
int level;
int year;
public Car(int level,int year) {
this.level=level;
this.year=year;
}
public double getMoney() {
return 200*this.level/(Math.sqrt(this.year));
}
}
class CarRentCompany{
public static double rentVehicles(Vehicle[] vs) {
double sum=0;
for(int i=0;i
sum+=vs[i].getMoney();
}
return sum;
}
}
图书列表
import java.util.LinkedList;
class Book{
String _n;
int _p;
String _w;
int _no;
Book(String name, int price, String author, int edition){
this._n = name;
this._p = price;
this._w = author;
this._no = edition;
}
String get_n() {return this._n;}
String get_w() {return this._w;}
int get_p() {return this._p;}
int get_no() {return this._no;}
public String toString(){
String s = "name: "+_n+", price: "+_p+", author: "+_w+", edition: "+_no;
System.out.println("name: "+_n+", price: "+_p+", author: "+_w+", edition: "+_no);
return s;
}
public boolean equals(Book t) {
if(this.get_n().equalsIgnoreCase(t.get_n()) == true
&& this.get_w().equalsIgnoreCase(t.get_w()) == true
&& this.get_no()== t.get_no()) {
return true;
}
return false;
}
}
class BookList{
LinkedList
BookList(){
this.booklist = new LinkedList<>();
}
public void addBook(Book t) {
booklist.add(t);
}
public void searchBook(Book t) {
boolean ok = true;
for(int i = 0, len = booklist.size(); i < len; ++i) {
if( t.equals(booklist.get(i)) ) {
System.out.println("found: " + i);
ok = false;
break;
}
}
if(ok) {
System.out.println("not found");
}
}
}
jmu-Java-05集合-List中指定元素的删除
public static List
List
String s[]=line.split("\s+");
for(int i=0;i
a.add(s[i]);
}
return a;
}
public static void remove(List
for(int i=0;i
if(list.get(i).equals(str)) {
list.remove(i);
i=0;
}else {
i++;
}
}
}
jmu-Java-06异常-多种类型异常的捕获
catch(Exception e){
if (choice.equals("number"))
System.out.println ("number format exception");
if (choice.equals("illegal"))
System.out.println ("illegal argument exception");
if (choice.equals("except"))
System.out.println ("other exception");
System.out.println (e);
}
可排序的学生类
class Student implements Comparable
int no;
String name;
public Student() {
no = 0;
name = "";
}
public Student(int no, String name) {
this.no = no;
this.name = name;
}
public int getNo() {
return no;
}
public void setNo(int no) {
this.no = no;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int compareTo(Student t1) {
// TODO Auto-generated method stub
return this.getName().compareTo(t1.getName());
}
public int hashCode() {
// TODO Auto-generated method stub
return no;
}
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Student other = (Student) obj;
if (no != other.no)
return false;
return true;
}
public String toString()
{
//return "no="+this.no+"&name="+this.name;
return "no="+this.no+"&name="+this.name;
}
}
汽车类
class Car{
public int speed = 0;
public String status = "off";
public void start() {
status="on";
speed=0;
}
public void stop() {
if(speed==0)
status="off";
}
public void speedUp() {
if(status=="on" && speed<160)
speed+=10;
}
public void slowDown() {
if(status=="on" && speed>0)
speed-=10;
}
}
设计直线类
class Point
{
public double x;
public double y;
public Point(double _x,double _y)
{
this.x=_x;
this.y=_y;
}
}
class Line
{
Point p1,p2;
public Line(Point p1,Point p2)
{
this.p1=p1;
this.p2=p2;
}
public double getLength()
{
return Math.sqrt(Math.pow((p1.x-p2.x), 2)+Math.pow((p1.y-p2.y), 2));
}
}
学生数统计
class Student {
String name;
int sex;
int age;
static int maleCount = 0;
static int femaleCount = 0;
public Student(String name, int sex, int age) {
this.name = name;
this.sex = sex;
this.age = age;
if (this.sex == 1) {
maleCount++;
} else if (this.sex == 0) {
femaleCount++;
}
}
public static int getMaleCount() {
return maleCount;
}
public static int getFemaleCount() {
return femaleCount;
}
}
Person类
class Person{
private String name;
private String sex;
private int age;
public void setName(String name_) {
name = name_;
}
public void setSex(String sex_) {
sex =sex_;
}
public void setAge(int age_) {
age = age_;
}
public void print() {
System.out.println("name:"+name+"; "+"sex:"+sex+"; "+"age:"+age);
}
}
Person类2
class Person{
private String name;
private String sex;
private int age;
Person(String name,String sex,int age){
this.name=name;
this.sex=sex;
this.age=age;
}
public void print() {
System.out.println("name:"+name+"; sex:"+sex+"; age:"+age);
}
}
学生类
import java.util.Arrays;
import java.util.Comparator;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
final int N = 3; // 学生个数
Scanner cin = new Scanner(System.in);
Student[] stu = new Student[N];
for(int i = 0; i < N; i ++ ) {
stu[i] = new Student(cin.nextInt(), cin.next(), cin.nextInt());
}
Arrays.sort(stu, new Comparator
@Override
public int compare(Student o1, Student o2) {
// TODO Auto-generated method stub
return o2.getScore() - o1.getScore();
}
});
for(int i = 0; i < N; i ++) {
stu[i].print();
}
}
}
家具类
class Furniture {
public int height;
public int length;
public int width;
public Furniture(int _length, int _width, int _height) {
this.length = _length;
this.width = _width;
this.height = _height;
}
public int getHeight(){
return this.height;
}
public int getLength(){
return this.length;
}
public int getWidth(){
return this.width;
}
}
Shape类
abstract class Shape{
abstract double getPerimeter();
abstract double getArea();
}
class Square extends Shape{
double len;
Square(double len){
this.len=len;
}
@Override
double getPerimeter() {
// TODO Auto-generated method stub
return 4*len;
}
@Override
double getArea() {
// TODO Auto-generated method stub
return len*len;
}
}
class Rectangle extends Square{
double width;
Rectangle(double len,double width) {
super(len);
// TODO Auto-generated constructor stub
this.width=width;
}
@Override
double getPerimeter() {
// TODO Auto-generated method stub
return 2*(len+width);
}
@Override
double getArea() {
// TODO Auto-generated method stub
return len*width;
}
}
class Circle extends Shape{
double r;
double pi=3.142;
Circle(double r){this.r=r;}
@Override
double getPerimeter() {
// TODO Auto-generated method stub
return 2*pi*r;
}
@Override
double getArea() {
// TODO Auto-generated method stub
return pi*r*r;
}
}
学生、大学生、研究生类
class Student{
int no;
String name,sex;
Student(int no,String name,String sex){this.no=no;this.name=name;this.sex=sex;}
public int getNo() {
return no;
}
public void setNo(int no) {
this.no = no;
}
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;
}
void attendClass(String className) {}
void print() {
System.out.println("no: "+no+"n"+
"name: "+name+"n"+
"sex: "+sex);
}
}
class CollegeStudent extends Student{
String major;
CollegeStudent(int no,String name,String sex,String major){
super(no,name,sex);
this.major=major;
}
public String getMajor() {
return major;
}
public void setMajor(String major) {
this.major = major;
}
void print() {
super.print();
System.out.println("major: "+major);
}
}
class GraduateStudent extends CollegeStudent{
String supervisor;
GraduateStudent(int no, String name, String sex, String major,String supervisor) {
super(no, name, sex, major);
// TODO Auto-generated constructor stub
this.supervisor=supervisor;
}
public String getSupervisor() {
return supervisor;
}
public void setSupervisor(String supervisor) {
this.supervisor = supervisor;
}
void doResearch() {System.out.println(name+" is doing research");}
void print() {
super.print();
System.out.println("supervisor: "+supervisor);
}
}
租车服务
abstract class Vehicle{
abstract double daycost();
}
class Truck extends Vehicle{
double load;
Truck(double load){this.load=load;}
@Override
double daycost() {
return load*1000;
}
}
class Keche extends Vehicle{
int seat;
Keche(int seat){this.seat=seat;}
@Override
double daycost() {
// TODO Auto-generated method stub
return (double)(seat*50.0);
}
}
class Car extends Vehicle{
int level;
int year;
Car(int level,int year){this.level=level;this.year=year;}
@Override
double daycost() {
// TODO Auto-generated method stub
return (double)(200*level)/Math.sqrt(year);
}
}
class CarRentCompany{
static double rentVehicles(Vehicle[] vs) {
double sum=0;
for(Vehicle a:vs) {
sum+=a.daycost();
}
return sum;
}
}
可定制排序的矩形
class Rectangle implements Comparable{
int length,width;
Rectangle(int a,int b){
this.length=a;
this.width=b;
}
public int getArea(){
return this.length*this.width;
}
@Override
public int compareTo(Object o) {
Rectangle a=(Rectangle) o;
if(a.getArea()>this.getArea())
return 1;
if(a.getArea()
return 0;
}
}
数群
import java.util.LinkedList;
import java.util.Scanner;
interface Integer{
public boolean contains(int a);
}
abstract class IntegerGroup implements Integer {
public boolean contains(int a) {
return true;
}
}
class Range extends IntegerGroup {
private int[] num;
public Range(int min,int max) {
num=new int[max-min+1];
int t=min;
for(int i=0;i
num[i]=t;
t++;
}
}
public boolean contains(int a) {
for(int i=0;i
if(num[i]==a)
return true;
}
return false;
}
}
class Enum extends IntegerGroup {
private int[] num;
public Enum(int[] a) {
num=new int[a.length];
System.arraycopy(a, 0, num, 0, a.length);
}
public boolean contains(int a) {
for(int i=0;i
if(num[i]==a)
return true;
}
return false;
}
}
class MultipleGroups{
LinkedList
public void add(IntegerGroup inter)
{
mu.add(inter);
}
public boolean contains(int a) {
for(int i=0;i
if(mu.get(i).contains(a)==true)
return true;
}
return false;
}
}
图书和音像租赁
import java.util.*;
public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
Media[] ms = new Media[n];
for (int i=0; i
String type = sc.next();
if (type.equals("book")) {
ms[i] = new Book(sc.next(), sc.nextDouble());
}else {
ms[i] = new DVD(sc.next());
}
}
double rent = MediaShop.calculateRent(ms, sc.nextInt());
System.out.printf("%.2f", rent);
}
}
abstract class Media{//根据题意Media时抽象类
abstract double getDailyRent();
}
class Book extends Media{//Book继承自Media
String name;
double price;
public Book(String name,double price) {
this.name=name;
this.price=price;
}
public double getDailyRent() {
return this.price*0.01;
}
}
class DVD extends Media{//DVD继承自Media
String name;
public DVD(String name) {
this.name=name;
}
public double getDailyRent() {
return 1;
}
}
class MediaShop{//MediaShop类
//提供静态方法!!!
public static double calculateRent(Media[] medias, int days) {
double sum=0;
for(Media m:medias) {
if(m instanceof DVD) {
DVD d=(DVD)m;
sum+=d.getDailyRent()*days;
}else if(m instanceof Book) {
Book b=(Book)m;
sum+=b.getDailyRent()*days;
}
}
return sum;
}
}
动物体系
class Animal {
public String name;
public String color;
public Animal(String name, String color) {
super();
this.name = name;
this.color = color;
}
public void introduce() {
}
}
class Cat extends Animal {
public String eyeColor;
public Cat(String name, String color, String eyeColor) {
super(name, color);
this.eyeColor = eyeColor;
}
public void introduce() {
System.out.printf("My name is %s, my color is %s, my eyecolor is %sn", this.name, this.color, this.eyeColor);
}
public void catchMouse() {
System.out.println("catch mouse");
}
}
class Dog extends Animal {
public int IQ;
public Dog(String name, String color, int iQ) {
super(name, color);
IQ = iQ;
}
public void catchFrisbee() {
System.out.println("catch frisbee");
}
public void introduce() {
System.out.printf("My name is %s, my color is %s, my IQ is %dn", this.name, this.color, this.IQ);
}
}
class TestAnimal {
public static void introduce(Animal a) {
if (a instanceof Dog) {
Dog d = (Dog) a;
d.introduce();
} else if (a instanceof Cat) {
Cat c = (Cat) a;
c.introduce();
}
}
public static void action(Animal a) {
if (a instanceof Dog) {
Dog d = (Dog) a;
d.catchFrisbee();
} else if (a instanceof Cat) {
Cat c = (Cat) a;
c.catchMouse();
}
}
}
设计一个Duck类及其子类
import java.util.*;
public class Main {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner scanner=new Scanner(System.in);
Duck rduck = new RedheadDuck();
rduck.display();
rduck.quack();
rduck.swim();
rduck.fly();
Duck gduck = new MallardDuck();
gduck.display();
gduck.quack();
gduck.swim();
gduck.fly();
}
}
//Duck类的定义
abstract class Duck { //吧Duck写成抽象类更易实现
public void quack() {
System.out.println("我会呱呱呱");
}
public void swim() {
System.out.println("我会游泳");
}
public void fly() {
System.out.println("我会飞");
}
abstract public void display();
}
//RedheadDuck类的定义
class RedheadDuck extends Duck {
public void display() {
System.out.println("我是一只红头鸭");
}
}
//MallardDuck类的定义
class MallardDuck extends Duck {
public void display() {
System.out.println("我是一只绿头鸭");
}
}
图书类
class Book {
String name;
int price;
String author;
int edition;
public Book(String name, int price, String author, int edition) {
this.name = name;
this.price = price;
this.author = author;
this.edition = edition;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getPrice() {
return price;
}
public void setPrice(int price) {
this.price = price;
}
public String getAuthor() {
return author;
}
public void setAuthor(String author) {
this.author = author;
}
public int getEdition() {
return edition;
}
public void setEdition(int edition) {
this.edition = edition;
}
@Override
public String toString() {
return "name: " + this.name +
", price: " + this.price +
", author: " + this.author +
", edition: " + this.edition;
}
@Override
public boolean equals(Object o) {
//if (this == o) return true;
if (o == null) return false;
else {
boolean result = false;
if (o instanceof Book) {
Book book = (Book) o;
//当两个Book对象的名称(不关心大小写,无空格)、作者(不关心大小写,无空格)、版本号相同时,认为两者表示同一本书。注意此处无关价格
if (book.name.equalsIgnoreCase(this.name)&&book.author.equalsIgnoreCase(this.author)&&book.edition==this.edition)
result = true;
}
return result;
}
}
}
手机类
class CellPhone {
String model;
int memory;
int storage;
int price;
public CellPhone(String model, int memory, int storage, int price) {
this.model = model;
this.memory = memory;
this.storage = storage;
this.price = price;
}
public String getModel() {
return model;
}
public void setModel(String model) {
this.model = model;
}
public int getMemory() {
return memory;
}
public void setMemory(int memory) {
this.memory = memory;
}
public int getStorage() {
return storage;
}
public void setStorage(int storage) {
this.storage = storage;
}
public int getPrice() {
return price;
}
public void setPrice(int price) {
this.price = price;
}
public String toString()
{
return "CellPhone [model:"+model+", memory:"+memory+", storage:"+storage+", price:"+price+"]";
}
public boolean equals(Object o)
{
boolean result=false;
if(o==null) return false;
else
{
CellPhone cell=(CellPhone) o;
if(cell.model.equals(this.model)&&cell.memory==this.memory&&cell.storage==this.storage)
result=true;
}
return result;
}
}
可定制排序的矩形
class RectangleComparator implements Comparator{
@Override
public int compare(Object o1, Object o2) {
Rectangle r1=(Rectangle)o1;
Rectangle r2=(Rectangle)o2;
if (r1.getArea() < r2.getArea()) return 1;
else if (r1.getArea() > r2.getArea()) return -1;
else return 0;
}
}
教师类
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner cin=new Scanner(System.in);
Teacher t1=new Teacher(cin.nextInt(),
cin.next(),
cin.nextInt(),
cin.next());
Teacher t2=new Teacher(cin.nextInt(),
cin.next(),
cin.nextInt(),
cin.next());
System.out.println(t1);
System.out.println(t2);
System.out.println(t1.equals(t2));
}
}
class Teacher
{
int no;
String name;
int age;
String seminary;
public Teacher(int no, String name, int age, String seminary) {
this.no = no;
this.name = name;
this.age = age;
this.seminary = seminary;
}
public int getNo() {
return no;
}
public void setNo(int no) {
this.no = no;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getSeminary() {
return seminary;
}
public void setSeminary(String seminary) {
this.seminary = seminary;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Teacher teacher = (Teacher) o;
boolean result=false;
if(this.no==teacher.no&&this.age==teacher.age&&this.name.equals(teacher.name)&&this.seminary.equals(teacher.seminary))
result=true;
return result;
}
@Override
public String toString() {
return "no: "+no+", name:"+name+", age: "+age+", seminary: "+seminary;
}
}
家电类
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Truck truck=new Truck();
truck.get();
int sum=truck.getSum();
System.out.println(sum);
}
}
interface Appliance
{
int getWeight();
}
//该货车上的所有家电,用一个集合(数组或集合类)表示
//数组的话考虑用二维数组,同时储存家电的种类和数量
//采用集合类的方法,创建一个App类
class App implements Appliance
{
int weight;
public App(int weight)
{
this.weight=weight;
}
@Override
public int getWeight()
{
return 0;
}
}
class TV extends App implements Appliance
{
public TV(int w)
{
super(w);
}
@Override
public int getWeight(){
return weight;
}
}
class WashMachine extends App implements Appliance
{
public WashMachine(int w)
{
super(w);
}
@Override
public int getWeight(){
return weight;
}
}
class AirConditioner extends App implements Appliance
{
public AirConditioner(int w)
{
super(w);
}
@Override
public int getWeight(){
return weight;
}
}
class Truck
{
Scanner sc=new Scanner(System.in);
int sum;
int num=sc.nextInt();
App a[]=new App[num];
//获取所有家电
public void get()
{
for (int i = 0; i < num ; i++) {
int n=sc.nextInt();
int w=sc.nextInt();
switch (n){
case 1:{
a[i]=new TV(w);break;
}
case 2: {
a[i]=new WashMachine(w);break;
}
case 3:{
a[i]=new AirConditioner(w);break;
}
default:break;
}
}
}
public int getSum()
{
sum=0;
for (int i = 0; i < num; i++) {
sum += a[i].getWeight();
}
return sum;
}
}
成绩管理系统
class CourseManagementSystem{
int A[][]=new int[100][2];//用来存放学生的成绩数据,学号就是数组下标
int a,b,n=0;
int q=0,w=0,e=0,r=0,t=0;//用来统计五个分数段的人数
public void add(int no,int grade){
if(A[no][1]!=0)//说明之前已经存入了数据
System.out.println("the student already exists");
else
{ A[no][1]=grade;
n++;
if(grade<=59)
q++;
else if(grade<=69)
w++;
else if(grade<=79)
e++;
else if(grade<=89)
r++;
else if(grade<=100)
t++;}
}
public void delete(int no){
if(A[no][1]==0)System.out.println("no such student");//说明还没有存入数据
else
{int grade1=A[no][1];
A[no][1]=0;
n--;
if(grade1<=59)
q--;
else if(grade1<=69)
w--;
else if(grade1<=79)
e--;
else if(grade1<=89)
r--;
else if(grade1<=100)
t--;}
}
public int query(int no){
return A[no][1];
}
public void statistic( ){
System.out.println("[0-59] : "+q+"n[60-69] : "+w+"n[70-79] : "+e+"n[80-89] : "+r+"n[90-100] : "+t);
}
}
学生信息管理
class Student implements Comparable{
int no;
String name;
Student(int a,String b){
this.no=a;
this.name=b;
}
public String toString() {
return "no="+this.no+"&name="+this.name;
}
@Override
public int compareTo(Object o) {
// TODO Auto-generated method stub
Student a=(Student) o;
return this.name.compareTo(a.name);
}
public int hashCode() {
return this.no;
}
public boolean equals(Object o) {
Student s=(Student) o;
if(this.no==s.no)
return true;
return false;
}
}



