jmu-PTA Java答案汇总（上）
2023-12-16 04:47:18
目录
7-213 jmu-java-m01-System.out.printf入门
7-28 编写Java程序，求13-23+33-43+…+973-983+993-1003的值。
Java练习第二章
7-21 统计符合条件元素的个数
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int n = scan.nextInt();
//计算能被3整除的奇数和偶数
int s = 0;
int d = 0;
for (int i = 1; i <= n; i++) {
if(i % 3 == 0) {
if(i % 2 == 0) {
d++;
}
else
s++;
}
}
System.out.println(s + "," + d);
}
}7-210 sdut-array2-1-矩阵转置（I）
import java.util.Scanner;
public class Main{
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int N = scanner.nextInt();
int[][] arr = new int[N][N];
for (int i = 0; i < N; i++) {
for (int j = 0; j < N; j++) {
arr[i][j] = scanner.nextInt();
}
}
for (int i = 0; i < N; i++) {
for (int j = 0; j < N; j++) {
System.out.print(arr[j][i]);
if(j < N -1)
System.out.print(" ");
}
System.out.println();
}
}
}7-211 JAVA-输入输出入门
import java.io.*;
import java.util.Scanner;
class Main{
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int x = scan.nextInt();
double y = scan.nextDouble();
System.out.println(x + y);
System.out.println(Math.sqrt(x + y));
System.out.print(String.format("%.6f",Math.sqrt(x+y)));
}
}7-212 sdut-入门-三个整数和、积与平均值
import java.io.*;
import java.util.Scanner;
class Main {
public static void main(String[] args)throws IOException {
Scanner scan = new Scanner(System.in);
int a = scan.nextInt();
int b = scan.nextInt();
int c = scan.nextInt();
System.out.print((a + b + c)+" ");
System.out.print((a * b * c) + " ");
System.out.print(String.format("%.2f",((a+b+c)/3.0)));
}
}
7-213 jmu-java-m01-System.out.printf入门
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner s = new Scanner(System.in);
int a = s.nextInt();
double b = s.nextDouble();
int x1 = s.nextInt();
int x2 = s.nextInt();
int x3 = s.nextInt();
System.out.println(a+" "
+Integer.toOctalString(a)+" "
+Integer.toHexString(a));
System.out.println(String.format("%6.2f", b));
System.out.println(String.format("%5d",x1)+" "+String.format("%5d",x2)+" "+String.format("%5d",x3));
System.out.println(String.format("%5d",x2)+" "+String.format("%5d",x3)+" "+String.format("%5d",x1));
System.out.println(String.format("%5d",x3)+" "+String.format("%5d",x1)+" "+String.format("%5d",x2));
}
}7-214 jmu-java-m02-循环求和
import java.io.*;
import java.util.Scanner;
class Main{
public static void main(String[]args){
Scanner s = new Scanner(System.in);
int n = s.nextInt();
int[] arr = new int[n];
int sum1 = 0;
int sum2 = 0;
for (int i = 0; i < n; i++) {
arr[i] = s.nextInt();
if(arr[i] % 2 == 0) {
sum2+=arr[i];
}
else
sum1+=arr[i];
}
System.out.println("奇数和="+sum1+", 偶数和="+sum2);
}
}7-215 编程题：统计符合条件元素的个数
import java.io.*;
import java.util.Scanner;
class Main{
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int n = scan.nextInt();
int s = 0;
int d = 0;
for (int i = 1; i <= n; i++) {
if(i % 3 == 0) {
if(i % 2 ==0)
d++;
else
s++;
}
}
System.out.println(s + "," + d);
}
}
7-216 jmu-java-m02-数组基本操作
import java.util.Scanner;
import java.util.Arrays;
public class Main{
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int n = scan.nextInt();
int[] R = new int[n];
for (int i = 0; i < n; i++) {
R[i] = scan.nextInt();
}
//排序
Arrays.sort(R);
System.out.println(Arrays.toString(R));
//逆序
for (int i = R.length-1; i >= 0 ; i--) {
System.out.print(R[i]+" ");
}
System.out.println();
//平均半径
double mid= Arrays.stream(R).sum()/(double)n;
System.out.println("平均半径="+mid);
//总面积
double area = 0;
for (int x:R) {
area+=x*x*Math.PI;
}
System.out.println("总面积="+String.format("%.6f",area));
}
}7-22 整数数组比较-Java
import java.util.Arrays;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int n = scan.nextInt();
int[] A = new int[n];
for (int i = 0; i < n; i++) {
A[i] = scan.nextInt();
}
int[] B = A.clone();
Arrays.sort(B);
int ab = 0;
int ba = 0;
int d = 0;
for (int i = 0; i < n; i++) {
if(A[i] > B[i]) {
ab++;
}
else if(A[i] < B[i]) {
ba++;
}
else
d++;
}
System.out.println(ab);
System.out.println(d);
System.out.println(ba);
}
}
7-23 求n以内所有能被3和5整除的正整数
import java.io.*;
import java.util.Scanner;
class Main{
public static void main(String[]args){
Scanner scan = new Scanner(System.in);
int n = scan.nextInt();
int key = 0;
for (int i = 1; i <= n; i++) {
if(i % 3 == 0 && i % 5 == 0) {
System.out.print(i+" ");
key++;
}
if(key == 10) {
System.out.println();
key -= 10;
}
}
}
}7-24 输出所有的水仙花数
import java.io.*;
class Main{
public static void main(String[]args){
for (int i = 100; i < 1000; i++) {
int a = i % 10;
int b = i / 10 % 10;
int c = i / 100;
if(a*a*a + b*b*b + c*c*c == i) {
System.out.println(i);
}
}
}
}7-25 编写一个程序解决爱因斯坦台阶问题
public class Main{
public static void main(String[]args){
int x = 1;
while(true) {
if(x % 2 == 1 && x % 3 == 2 && x % 4 ==3
&&x % 5 == 4 && x % 6 ==5 && x% 7 == 0) {
System.out.println(x);
break;
}
x++;
}
}
}7-26 判断一个数是否为回文数
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int n = scan.nextInt(); //n是要判断的数
int num = 1; //num有几位数
int key = 1; //key用于计算
int tmp = n;
while(tmp > 10) {
tmp /= 10;
num++;
key *= 10;
}
tmp = n;
while(tmp > 10) {
int a = tmp / key;
int b = tmp % 10;
if(a != b) {
System.out.println(n + " 不是回文数");
return;
}
tmp%=key;
tmp/=10;
key/=100;
}
System.out.println(n + " 是回文数");
}
}7-27 编写程序求1000之内的所有完全数。
class Main{
public static void main(String[] args) {
for (int i = 1; i < 1000; i++) {
int sum = 0;
for (int j = 1; j < i; j++) {
if(i % j == 0) {
sum += j;
}
}
if(sum == i) {
System.out.print(i+" ");
}
}
}
}7-28 编写Java程序，求13-23+33-43+…+973-983+993-1003的值。
class Main {
public static void main(String[] args) {
int sum = 0;
int k = 1;
for (int i = 13; i <= 1003; i+=10) {
sum += i * k;
k *= -1;
}
System.out.println(sum);
}
}7-29 用foreach求数组之和
import java.util.Scanner;
public class Main{
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int n = scan.nextInt();
int[] arr = new int[n];
for (int i = 0; i < n; i++) {
arr[i] = scan.nextInt();
}
int sum = 0;
for(int x:arr) {
sum+=x;
}
System.out.println(sum);
}
}
Java练习第三章
6-31 定义复数类Complex
class Complex {
double a;
double b;
public Complex(double a,double b) {
this.a = a;
this.b = b;
}
public Complex add(Complex c) {
Complex tmp = new Complex(this.a,this.b);
tmp.a+=c.a;
tmp.b+=c.b;
return tmp;
}
public Complex sub(Complex c) {
Complex tmp = new Complex(this.a,this.b);
tmp.a-=c.a;
tmp.b-=c.b;
return tmp;
}
public String getString() {
return "("+a+","+b+"i)";
}
}6-32 比较两个对象是否相等
class Bird {
String color;
int size;
public Bird(String color, int size) {
this.color = color;
this.size = size;
}
public String equals(Bird b) {
if(this.color == b.color && this.size == this.size)
return "同一只鸟";
return "不同一只鸟";
}
}6-33 利用静态变量实现自动编号
class Book {
String name;
double price;
int id;
public static int num = 0;
public Book() {
num++;
id=num;
}
public Book(String name, double price) {
this();
this.name = name;
this.price = price;
}
public String toString() {
return "编号：" +id+
"，书名：" + name +
"，价格：" + price;
}
}6-34 编写一个单例类
class SingleTest {
private static int bucket = 100;
private static SingleTest test = new SingleTest();
public static SingleTest getInstance() {
return test;
}
public void addobj() {
System.out.println("当前的储量是"+(++bucket));
}
public void delOjb() {
System.out.println("当前的储量是"+(--bucket));
}
}6-35 定义派生类Rectangle
class Rectangle extends Shape {
protected double width;
protected double height;
public Rectangle(double width, double height) {
this.width = width;
this.height = height;
}
public Rectangle(int id, String color, double width, double height) {
super(id, color);
this.width = width;
this.height = height;
}
@Override
public void area() {
System.out.println(width * height);
}
}6-36 编写雇员工资支付程序。
class Manager extends Employee{
private int salary;
public Manager(String name, String type, int salary) {
super(name, type);
this.salary = salary;
}
@Override
public int getSalary() {
return salary;
}
}
class Salesman extends Employee {
private int salary;
private int salaryRaise;
public Salesman(String name, String type, int salary, int salaryRaise) {
super(name, type);
this.salary = salary;
this.salaryRaise = salaryRaise;
}
@Override
public int getSalary() {
return salary+salaryRaise;
}
}
class Worker extends Employee {
private int salary;
private int days;
public Worker(String name, String type, int salary, int days) {
super(name, type);
this.salary = salary;
this.days = days;
}
public int getSalary() {
return salary*days;
}
}6-37 图书和音像租赁
class Media {
double getDailyRent() {
return 0;
}
}
class Book extends Media {
String name;
double price;
public Book(String name, double price) {
this.name = name;
this.price = price;
}
double getDailyRent() {
return price*0.01;
}
}
class DVD extends Media {
String name;
public DVD(String name) {
this.name = name;
}
double getDailyRent() {
return 1.0;
}
}
class MediaShop extends Media {
static double calculateRent(Media[] medias, int days) {
double sum = 0;
for (int i = 0; i < medias.length; i++) {
sum+=medias[i].getDailyRent()*days;
}
return sum;
}
}6-38 定义商品类
class Goods {
private String id;
private String name;
private double price;
public Goods(String id, String name, double price) {
this.id = id;
this.name = name;
this.price = price;
}
@Override
public String toString() {
return id + "," + name + "," + price ;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public double getPrice() {
return price;
}
public void setPrice(double price) {
this.price = price;
}
}6-39 实现部门介绍功能需求说明（继承）
class Department {
private String sector;
private String name;
private int num;
private String work;
public Department(String sector, String name, int num, String work) {
this.sector = sector;
this.name = name;
this.num = num;
this.work = work;
}
public String printIntro() {
return "部门名称："+sector+"\n"
+"经理："+name+"\n"
+"员工人数："+num+"\n"
+"部门职责："+work+"\n";
}
}
class HR extends Department {
private int plan;
public HR(String sector, String name, int num, String work, int plan) {
super(sector, name, num, work);
this.plan = plan;
}
@Override
public String printIntro() {
return super.printIntro()+"招聘目标："+plan+"人";
}
}
class RD extends Department {
private int number;
public RD(String sector, String name, int num, String work, int number) {
super(sector, name, num, work);
this.number = number;
}
@Override
public String printIntro() {
return super.printIntro()+"研发项目数:"+number+"人";
}
}6-310 高速公路车辆收费系统（继承）
class Vehicle {
int length;
String plateNo;
public Vehicle(int length, String plateNo) {
this.length = length;
this.plateNo = plateNo;
}
public Vehicle(int length) {
this.length = length;
}
public String getString() {
return "车牌号："+plateNo+"\n"
+"车长："+length+"\n";
}
public double getRate() {
return 0;
}
}
class Bus extends Vehicle{
int passengers;
public Bus(int length, String plateNo, int passengers) {
super(length, plateNo);
this.passengers = passengers;
}
@Override
public String getString() {
return super.getString()+"核定载人数："+passengers;
}
@Override
public double getRate() {
if(length < 6000) {
return 0.6;
}
else {
return 0.9;
}
}
}
class Truck extends Vehicle {
double weight;
int numbersOfAxles;
public Truck(int length, String plateNo, double weight, int numbersOfAxles) {
super(length, plateNo);
this.weight = weight;
this.numbersOfAxles = numbersOfAxles;
}
@Override
public String getString() {
return super.getString()+"最大允许总重量："+weight
+"\n"+"车轴数:"+numbersOfAxles;
}
@Override
public double getRate() {
if(numbersOfAxles == 2) {
if(length < 6000 && weight < 4500)
return 0.6;
else
return 0.9;
}
if (numbersOfAxles == 3)
return 1.02;
if(numbersOfAxles == 4)
return 1.315;
if(numbersOfAxles == 5 || numbersOfAxles == 6)
return 1.428;
else
return -1;
}
}6-311 模拟控制动物叫的功能（多态）
class Animal {
public void cry() {
System.out.println("动物叫......");
}
}
class Dog extends Animal {
@Override
public void cry() {
System.out.println("汪汪汪......");
}
}
class Cat extends Animal {
@Override
public void cry() {
System.out.println("喵喵喵......");
}
}
class Duck extends Animal {
@Override
public void cry() {
System.out.println("嘎嘎嘎......");
}
}
class Host {
public void letCry(Animal animal) {
animal.cry();
}
}6-312 使用多态实现图书馆计算罚金功能
class Book {
String name;
int borrowDays;
public Book(String name) {
this.name = name;
}
public int calFines(int borrowDays) {
return 0;
}
public String getName() {
return name;
}
}
class AdultBook extends Book {
public AdultBook(String name) {
super(name);
}
@Override
public int calFines(int borrowDays) {
int num = borrowDays - 21;
if(num <= 0)
return 0;
if(num <= 3)
return num * 2;
else
return (num - 3) * 5 + 3 * 2;
}
}
class KidBook extends Book {
public KidBook(String name) {
super(name);
}
public int calFines(int borrowDays) {
int num = borrowDays - 21;
if(num <= 0)
return 0;
else
return num;
}
}
class Disc extends Book {
public Disc(String name) {
super(name);
}
public int calFines(int borrowDays) {
int num = borrowDays - 14;
if(num <= 0)
return 0;
if(num <= 3)
return num * 5;
else
return (num - 3) * 10 + 3 * 5;
}
}
class Customer {
public double calTotalFines(Book books[], int borrowDays) {
int sum = 0;
for (int i = 0; i < books.length; i++) {
sum += books[i].calFines(borrowDays);
}
return sum;
}
}7-31 设计一个People类
public class Main {
public static void main(String[] args) {
/********* begin *********/
// 声明并实例化一Person对象p
Person p = new Person();
// 给p中的属性赋值
p.setName("张三");
p.setAge(18);
// 调用Person类中的talk()方法
p.talk();
/********* end *********/
}
}
// 在这里定义Person类
class Person {
private String name;
private int age;
public void talk() {
System.out.println("我是："+name+"，今年："+age+"岁");
}
public String getName() {
return name;
}
public int getAge() {
return age;
}
public void setName(String name) {
this.name = name;
}
public void setAge(int age) {
this.age = age;
}
}7-32 定义商品类，封装成员变量，输出对象
class Shop {
private String id;
private String name;
private double price;
public Shop(String id ,String name,double price) {
this.id=id;
this.name=name;
this.price=price;
}
public String toString() {
return id+","+name+","+price;
}
public String getId() {
return id;
}
public String getName() {
return name;
}
public double getPrice() {
return price;
}
public void setId(String id) {
this.id = id;
}
public void setName(String name) {
this.name = name;
}
public void setPrice(double price) {
this.price = price;
}
}
public class Main {
public static void main(String[] args) {
Shop s = new Shop("WJ002","记事本",5.5);
System.out.println(s.toString());
}
}7-33 单例类练习
class Printer {
String number;
double price;
private static Printer P = new Printer("惠普",3400);
private Printer(String number,double price) {
this.price=price;
this.number=number;
}
public static Printer getPrinter() {
return P;
}
public String toString() {
return "型号为："+number+",价格为："+price;
}
}
public class Main {
public static void main(String[] args) {
Printer P = Printer.getPrinter();
System.out.println(P.toString());
}
}
文章来源:https://blog.csdn.net/linsc_05/article/details/135023615
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本文来自互联网用户投稿，该文观点仅代表作者本人，不代表本站立场。本站仅提供信息存储空间服务，不拥有所有权，不承担相关法律责任。 如若内容造成侵权/违法违规/事实不符，请联系我的编程经验分享网邮箱：veading@qq.com进行投诉反馈，一经查实，立即删除！