前三次大作业博客总结
第1~3次大作业博客
前言
java语言和c语言真的很不同！c是面向过程，它更加注重程序的执行过程，需要程序员手动管理内存等资源。java是面向对象，它更注重于对象的概念，提供了更高级的特性如继承、封装、多态等，同时也有自动内存管理机制（垃圾回收），使得程序员可以更专注于业务逻辑而不用过多关注底层细节。另外，题目难度和代码的复杂度来说，java也远远大于c，我们需要摆脱c语言的思维，去转变思维进行面向对象的编程，重点是如何设计对象以及对象之间的交互，而不再像C那样只关注函数和数据。这需要习惯于思考更高层次的抽象和模块化思维。
第一次作业
1.知识点：多个类的使用，类的初始化，其中一个类可以调用另一个类的方法或者访问其属性，创建对象进行使用类，多个类之间的调用可以通过在一个类中创建另一个类的对象来实现，然后通过这些对象之间的方法调用或属性访问来进行交互。数据的保存和输出，可以使用数组、集合（如ArrayList或LinkedList）等数据结构，如何将输入的数据拆分转化并且保存留用，通过字符串的分割（如使用split方法）和类型转换来实现。对字符的处理，比对，判断
2.题量适中，难度适中
7-1 设计一个风扇Fan类
import java.util.*;
class Fan{
int SLOW=1,MEDIUE=2,FAST=3;
private int speed=1;
private boolean on=false;
private double radius=5;
private String color="white";
Fan()
{}
public Fan(int fanSpeed,boolean fanOn,double fanRadius,String fanColor)
{
this.speed=fanSpeed;
this.on=fanOn;
this.radius=fanRadius;
this.color=fanColor;
}
public String toString()
{
String s;
if(this.on==false) {
s="speed "+speed+"\n";
s=s+"color "+color+"\n";
s=s+"radius "+radius+"\n";
s=s+"fan is off";
}else {
s="speed "+speed+"\n";
s=s+"color "+color+"\n";
s=s+"radius "+radius+"\n";
s=s+"fan is on";
}
return s;
}
}
public class Main{
public static void main(String[] args) {
Fan fan1=new Fan();
Scanner input=new Scanner(System.in);
int fanSpeed=input.nextInt() ;
boolean fanOn=input.nextBoolean();
double fanRadius=input.nextDouble();
String fanColor=input.next();
Fan fan2=new Fan(fanSpeed, fanOn,fanRadius,fanColor);
System.out.println("-------\n"+ "Default\n"+ "-------");
System.out.println(fan1.toString());
System.out.println("-------\n"+ "My Fan\n"+ "-------");
System.out.println(fan2.toString());
}
}
7-2 类和对象的使用
import java.util.*;
class Student{
private String name;
private String sex;
private String studentID;
private int age;
private String major;
public Student()
{}
public Student(String name,String sex,String studentID,int age,String major)
{
this.name=name;
this.sex=sex;
this.studentID=studentID;
this.age=age;
this.major=major;
}
// public getter()
//{
//}
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 String getStudentID() {
return studentID;
}
public void setStudentID(String studentID) {
this.studentID = studentID;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getMajor() {
return major;
}
public void setMajor(String major) {
this.major = major;
}
public String toString()
{
return "姓名：" + name + "，性别：" + sex + "，学号：" + studentID + ",年龄：" + age + ",专业：" + major;
}
public void printInfo()
{
System.out.println(toString());
}
}
public class Main {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
String name = input.next();
String sex = input.next();
int age = input.nextInt();
String major = input.next();
String studentID = input.next();
Student student=new Student(name,sex,studentID,age,major);
student.printInfo();
}
}
7-3 成绩计算-1-类、数组的基本运用
import java.util.Scanner;
class Student {
private String id;
private String name;
private int chinese;
private int math;
private int physics;
Student ()
{}
public Student(String id, String name, int chinese, int math, int physics) {
this.id = id;
this.name = name;
this.chinese = chinese;
this.math = math;
this.physics = physics;
}
public int sum() {
return chinese + math + physics;
}
public double Average() {
return sum() / 3.0;
}
public String getName() {
return name;
}
public String getId() {
return id;
}
public int getChinese() {
return chinese;
}
public int getPhysics() {
return physics;
}
public int getMath() {
return math;
}
}
public class Main {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
Student[] students = new Student[5];
int i;
for (i = 0; i < 5; i++) {
String[] in = input.nextLine().split(" ");
String id = in[0];
String name = in[1];
int chinese = Integer.parseInt(in[2]);
int math = Integer.parseInt(in[3]);
int physics = Integer.parseInt(in[4]);
students[i] = new Student(id, name, chinese, math, physics);
}
for (i = 0; i < 5; i++) {
int sum = students[i].sum();
double average= students[i].Average();
System.out.printf("%s %s %d %.2f\n",students[i].getId(), students[i].getName(), sum, average);
}
}
}
7-4 成绩计算-2-关联类
import java.util.Scanner;
class Grade{
private int day;
private int finall;
public Grade(int day,int finall)
{
this.day=day;
this.finall=finall;
}
public int test()
{
int test;
test=(int)(day*0.4+finall*0.6);
return test;
}
public int getday()
{
return day;
}
public int getfinall()
{
return finall;
}
}
class Student {
private String id;
private String name;
private Grade chinese;
private Grade math;
private Grade physics;
Student ()
{}
public Student(String id, String name ) {
this.id = id;
this.name = name;
//this.chinese = chinese;
//this.math = math;
//this.physics = physics;
}
public int getall()
{
return chinese.test()+math.test()+physics.test();
}
public double getavg()
{
double sum=chinese.test()+math.test()+physics.test();
return (double)(sum/3);
}
public double getavgday()
{
double sum=chinese.getday()+math.getday()+physics.getday();
return (double)(sum/3);
}
public double getavgfinall()
{
double sum=chinese.getfinall()+math.getfinall()+physics.getfinall();
return (double)(sum/3);
}
public String getName() {
return name;
}
public String getId() {
return id;
}
public Grade getchinese() {
return chinese;
}
public Grade getphysics() {
return physics;
}
public Grade getmath() {
return math;
}
public void setchinese(Grade chinese) {
this.chinese = chinese;
}
public void setphysics(Grade physics) {
this.physics = physics;
}
public void setmath(Grade math) {
this.math = math;
}
}
public class Main {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
Student[] students = new Student[3];
Grade[] grades=new Grade[3];
int i,count=0;
for(i=0;i<9;i++)
{
String id= input.next();
String name = input.next();
String project = input.next();
int day =input.nextInt();
int finall =input.nextInt();
int j=i%3;
if(j==0)
{
students[count]=new Student(id,name);
students[count].setchinese(new Grade(day,finall));
}
if(j==1)
{
students[count].setmath(new Grade(day,finall));
}
if(j==2)
{
students[count].setphysics(new Grade(day,finall));
count++;
}
}
for (i = 0; i < 3; i++) {
System.out.printf("%s %s %d %.2f %.2f %.2f\n",students[i].getId(), students[i].getName(), students[i].getall() , students[i].getavgday(),students[i].getavgfinall(),students[i].getavg());
}
}
}
7-5 答题判题程序-1
点击查看代码
import java.util.*;
class Question{
private int id;//编号
private String in;//内容
private String standardanswer;//标准答案
public Question(int id, String in, String standardanswer) {
this.id = id;
this.in = in;
this.standardanswer = standardanswer;
}
public void setid(int id)
{
this.id=id;
}
public void setin(String in)
{
this.in=in;
}
public void setstandardanswer(String standardanswer)
{
this.standardanswer=standardanswer;
}
public int getid()
{
return id;
}
public String getin()
{
return in;
}
public String getstandardanswer()
{
return standardanswer;
}
public boolean judje(String answer)
{//判断
//int flag=0;
return(standardanswer.equals(answer));
// flag=1;
// return flag;
}
}
class Paper
{
private Question[] list;//题目列表
private int num;//题目数量
public Paper(int num) {
this.num=num;
this.list = new Question[num];
}
public Question getlist(int i)
{
return list[i];
}
public int getnum() {
return num;
}
/* public boolean judje2(int id,String answer)
{//判断
return(list[id-1].judje(answer));
//return flag;
} */
public boolean judje2(int id, String answer)
{//判断
if (list[id-1] != null) {
return list[id-1].judje(answer);
} else {
// 处理题目为空的情况，这里简单地返回false
return false;
}
}
public void save(int id,Question question)
{//保存题目
list[id-1]=question;
}
}
class Anspaper//答卷
{
private Paper papers;//试卷
private String[] answer;//答案列表
private boolean[] judje;//判题列表（t or f）
public Anspaper(Paper papers) {
this.papers = papers;
this.answer = new String[papers.getnum()];
this.judje = new boolean[papers.getnum()];
}
public void judje3()//判题
{int i=0;
for (i = 0; i < papers.getnum(); i++) {
judje[i] = papers.judje2(i + 1, answer[i]);
}
}
public void print()//输出
{
for (int i = 0; i < papers.getnum(); i++) {
System.out.println( papers.getlist(i).getin() +"~"+answer[i]
);
}
for (int i = 0; i < papers.getnum(); i++) {
if(i<papers.getnum()-1)
System.out.print((judje[i] ? "true" : "false")+" ");
if(i==papers.getnum()-1)
System.out.print((judje[i] ? "true" : "false"));
}
}
public void saveans(int id ,String answers)
{//保存答案
if(id==1)
answer[id-1]=answers;
if(id>1)
answer[id - 1] = answers.substring(3);
//answer[id-1]=answers;
}
public String getanswer(int i)
{
return answer[i];
}
}
public class Main{
public static void main(String[] args){
Scanner input=new Scanner(System.in);
int num=input.nextInt();
input.nextLine(); //
Paper papers=new Paper(num);
for(int i=0;i<num;i++)
{
String[] strings = input.nextLine().split("#");
int id = Integer.parseInt(strings[1].substring(2).trim());
String in = strings[2].substring(2);
String standardanswer = strings[3].substring(2);
papers.save(id, new Question(id,in.trim(), standardanswer.trim()));
}
Anspaper answerpaper=new Anspaper(papers);
while (input.hasNextLine()) {
String line = input.nextLine();
if (line.equals("end"))
break;
String[] answer = line.substring(3).split(" ");
for (int i = 0; i < answer.length; i++) {
answerpaper.saveans(i + 1, answer[i]);
}
}
/*while(input.hasNextLine())
{
String line=input.nextLine();
if(line.equals("end"))
break;
//String[] str=input.nextLine().split(" ");
String[] answer=line.substring(3).split(" ");
for (int i=0;i<answer.length;i++)
{
answerpaper.saveans(i+1,answer[i]);
}
}*/
answerpaper.judje3();
answerpaper.print();
input.close();
}
}
第二次作业
1.知识点:数据的排序，动态数组和链表的使用，类与对象的运用，对于乱序输入数据的处理，可以先将数据存储在数组或集合中，然后使用排序算法对其进行排序或者使用Map来进行存储。拆分可以使用字符串的split方法或者正则表达式来实现，将数据按照特定的规则进行分割。缺失数据的处理可以通过特定的标记或者占位符来表示缺失，并在程序中进行相应的处理。多行数据的处理可以使用循环结构逐行读取数据，并进行相应的处理。题目与分值的对应和统计可以使用Map或者其他数据结构来进行存储，循环多次进行判断输出等，map的运用，数据的遍历和使用
2.题量偏大，难度偏高
7-4 答题判题程序-2
点击查看代码
import java.util.*;
class Question {
private int id; // 编号
private String in; // 内容
private String standardAnswer; // 标准答案
public Question(int id, String in, String standardAnswer) {
this.id = id;
this.in = in;
this.standardAnswer = standardAnswer;
}
public void setId(int id) {
this.id = id;
}
public void setIn(String in) {
this.in = in;
}
public void setStandardAnswer(String standardAnswer) {
this.standardAnswer = standardAnswer;
}
public int getId() {
return id;
}
public String getIn() {
return in;
}
public String getStandardAnswer() {
return standardAnswer;
}
public boolean judge(String answer) {
return standardAnswer.equals(answer);
}
}
class Paper {
int paperid;//试卷编号
private ArrayList<Question> list; // 题目列表
List<Score> Scores;
public Paper() {
this.list = new ArrayList<>();
}
public Paper(int paperid) {
this.paperid = paperid;
this.Scores =new ArrayList<>();
}//初始化和创建map
public void addQuestion(Question question) {
list.add(question);
}
public Question getQuestion(int i) {
return list.get(i);
}
public int getNumQuestions() {
return list.size();
}
public void addScore(Score score) {//将题目的序号和对应分数写入
Scores.add(score);
}
public List<Score> getScores() {
return Scores;
}
public boolean judgeQuestion(int id, String answer) {
if (id >= 1 && id <= list.size()) {
return list.get(id - 1).judge(answer);
} else {
return false; // 题目编号超出范围返回false
}
}
}
class AnswerPaper {
int ansid;//答卷编号
private Paper paper; // 试卷
// ArrayList<String> answers; // 答案列表
List<String> answers;//学生答案数组
public AnswerPaper(int ansid) {
this.ansid=ansid;
// this.paper = paper;
this.answers = new ArrayList<>();
}
public AnswerPaper(Paper paper) {
//this.ansid=ansid;
this.paper = paper;
this.answers = new ArrayList<>();
}
public void addAnswer(String answer) {
answers.add(answer);
}
public void judgeAnswers() {
for (int i = 0; i < paper.getNumQuestions(); i++) {
String answer = i <answers.size() ? answers.get(i) : "answer is null";
if(answer=="answer is null")
{ System.out.println("answer is null");
}
else
{
boolean result = paper.judgeQuestion(i + 1, answers.get(i));
System.out.println(paper.getQuestion(i).getIn()+ "~" + answers.get(i) + "~" + result);
}
}
}
public void printScore() {
int totalScore = 0;
for (int i = 0; i < paper.getNumQuestions(); i++) {
if (i < answers.size() && paper.judgeQuestion(i + 1, answers.get(i))) {
totalScore += 10; // 正确答案得10分
}
}
System.out.println(totalScore / 10 + " " + totalScore % 10 + " 0~" + totalScore); // 输出得分
}
}
class Score{
int num;//题号
int score;//分数
public Score(int num,int score) {//初始化
this.num = num;
this.score= score;
}
public int getNum()
{ return num;
}
public int getScore()
{ return score;
}
}
if (line.startsWith("#N:")) {
String[] parts = line.split(" ");
// String[] parts = line.split("#N:| #Q:| #A:");
int id = Integer.parseInt(parts[0].substring(3));
String in = parts[1].substring(3);
String standardAnswer = parts[2].substring(3);
question1.add(new Question(id, in, standardAnswer));
paper.addQuestion(new Question(id, in, standardAnswer));
}
第三次大作业
1.知识点：封装性，它通过将数据和方法封装在类的内部，只对外部提供有限的接口来实现。日期类的使用日期类的方法，可以通过Java提供的Date类或者更加强大和灵活的LocalDate类来实现，它们提供了丰富的日期操作方法，如获取年份、月份、日期等，以及日期间的比较和计算等功能。类与类之间的联系，通过这些对象之间的方法调用或者属性访问来进行交互。调用，删除信息，乱序混合输入，根据需求进行排序或者其他处理。运用正则表达式可以对输入数据进行格式验证，以确保输入数据符合特定的格式要求，并进行错误情况的处理。错误引用的处理，错误格式，乱序交错输入的拆分保存调用输入数据 ，储存数据，输入为空的情况处理，可以在程序中进行判断并给出相应的提示。分情况处理
2.题量大，难度高
7-3 答题判题程序-3
点击查看代码
class Student {//学生及答案
private String id;//学号
private String name;//姓名
int sheetNumber;//答卷编号
Map<Integer, String> answers;//答案
public Student(String id, int SheetNumber) {
this.id = id;
this.sheetNumber = sheetNumber;
//this.name = name;
answers = new HashMap<>();
}
public void addAnswer(int questionNumber, String answer) {
answers.put(questionNumber, answer);
}
public String getId() {
return id;
}
public String getName() {
return name;
}
public Map<Integer, String> getAnswers() {
return answers;
}
}
private static void processInput(String line) {//判断输入
if (line.startsWith("#N:")) {
processQuestion(line);
} else if (line.startsWith("#T:")) {
processTestPaper(line);
} else if (line.startsWith("#X:")) {
processStudent(line);
} else if (line.startsWith("#S:")) {
processAnswer(line);
} else if (line.startsWith("#D:")) {
processDeletedQuestion(line);
}
else
{
System.out.println("wrong format:"+line);
}
}
private static void processQuestion(String line) {//N
String lines = "^#N:(.*) #Q:(.*) #A:(.*)$";
Pattern pattern = Pattern.compile(lines);
Matcher matcher = pattern.matcher(line);
if(matcher.matches())
{
String[] parts = line.split("#");
String number = parts[1].substring(2);
number=number.trim();
String content = parts[2].substring(2);
content=content.trim();
String answer = parts[3].replace("A:", "");
answer=answer.trim();
Question a=new Question(Integer.parseInt(number), content, answer);
questions.add(a);
}
else
{ System.out.println("wrong format:"+line);
}
}
设计与分析
第一次大作业
主要是类与类之间的调用，相互联系和对字符的处理。不过一开始对类还并不熟悉，不能熟练运用。
第二次大作业
没有了题目个数，这就要用到动态数组及其相关函数。还新增了试卷，新增试卷类，建立试卷、题目、答卷之间的联系。还要把题目对应的分数一一对应计算
第三次大作业
主要是对错误情况的处理，多用正则表达式限制输入格式，要考虑多种情况，对输入的要求较高，注意细节，特别是内容为空的情况。新增了学生类，注意类之间的对应匹配。
踩坑心得
1.非零返回！！！！！真的害惨我了，每次都有非零返回，不同于编译错误，非零返回并不好找哪里出错了，也不好修改。但是大概率是输入的错误，所以要仔细检查输入的地方有没有可能输入为空，或者没进行输入就直接用了对应的变量，也就是变量还未初始化未赋值。
点击查看代码
> Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: Index 1 out of bounds for length 1
> at Main.processStudent(Main.java:148)
> at Main.processInput(Main.java:111)
> at Main.main(Main.java:99)
2.静态static
> Main.java:142: error: non-static variable testPapers cannot be referenced from a static context
> for (int paperNumber : testPapers.keySet()) {
> ^
> Main.java:143: error: non-static variable testPapers cannot be referenced from a static context
> TestPaper testPaper = testPapers.get(paperNumber);//创建遍历到的当前的试卷
> ^
> Main.java:156: error: non-static variable answerSheets cannot be referenced from a static context
> for(int paperNumber : answerSheets.keySet())
> ^
> Main.java:158: error: non-static variable testPapers cannot be referenced from a static context
> if(!testPapers.containsKey(paperNumber))
> ^
> Main.java:162: error: non-static variable testPapers cannot be referenced from a static context
> TestPaper testPaper = testPapers.get(paperNumber);//创建遍历到的当前的试卷
> ^
> Main.java:170: error: non-static variable answerSheets cannot be referenced from a static context
> List<Student> AnswerSheets = answerSheets.get(paperNumber);
> ^
> Main.java:180: error: non-static variable questions cannot be referenced from a static context
> for(Question question : questions)
> ^
> Main.java:208: error: non-static variable deletes cannot be referenced from a static context
> { if(!deletes.contains(question.getNumber()))
> ^
> Main.java:227: error: non-static variable students cannot be referenced from a static context
> String studentname = students.get(answerSheet.getId());
> ^
> Main.java:238: error: non-static variable deletes cannot be referenced from a static context
> if(answer.equals(question.answer)&&!deletes.contains(question.getNumber()))
> ^
> Main.java:322: error: non-static variable questions cannot be referenced from a static context
> questions.add(a);
> ^
> Main.java:346: error: non-static variable testPapers cannot be referenced from a static context
> testPapers.put(paperNumber, testPaper);
> ^
> Main.java:360: error: non-static variable students cannot be referenced from a static context
> students.put(IDname[0], IDname[1]);
> ^
> Main.java:373: error: incompatible types: int cannot be converted to String
> Student answerSheet=new Student(sheetNumber,studentID);
> ^
> Main.java:385: error: non-static variable answerSheets cannot be referenced from a static context
> if (answerSheets.containsKey(sheetNumber))
> ^
> Main.java:387: error: non-static variable answerSheets cannot be referenced from a static context
> answerSheets.get(sheetNumber).add(answerSheet);
> ^
> Main.java:392: error: non-static variable answerSheets cannot be referenced from a static context
> answerSheets.put(sheetNumber,list);
> ^
> Main.java:406: error: non-static variable deletes cannot be referenced from a static context
> deletes.add(Integer.parseInt(number[1]));
> ^
> Main.java:415: error: non-static variable students cannot be referenced from a static context
> for (Student student : students) {
> ^
> Main.java:416: error: non-static variable testPapers cannot be referenced from a static context
> for (TestPaper testPaper : testPapers) {
> ^
> Main.java:433: error: cannot find symbol
> if (deletedQuestions.contains("the question " + questionNumber + " invalid~0")) {
> ^
> symbol: variable deletedQuestions
> location: class Main
> Main.java:454: error: non-static variable questions cannot be referenced from a static context
> for (Question question : questions) {
> ^
> Main.java:463: error: non-static variable students cannot be referenced from a static context
> for (Student student : students) {
> ^
> Note: Some messages have been simplified; recompile with -Xdiags:verbose to get full output
3.类中的私有变量，是不能直接调用的，由于封闭性，需要调用相应的get函数
4.注释！！！很多时候没加注释真的忘了自己写的是什么，这样非常不利于后续的改进
改进建议：在编码中确实有很多地方可以改进，让我分享一些建议：
-
清晰的变量命名： 在编写代码时，使用清晰、具有象征性的变量名是非常重要的。这有助于他人理解代码，也方便自己在回顾代码时理解。例如，
ans可能不够清晰，可以考虑更具描述性的名称>answer -
代码重构： 定期进行代码重构是一个好习惯，可以通过将重复的代码提取为方法或者函数，提高代码的复用性和可维护性。此外，也可以根据需要进行代码结构的优化，使其更加简洁和清晰。
通过不断地改进和优化，可以使代码更加可读、可维护、可测试和可扩展，从而实现可持续的开发和改进。
总结
对本阶段的三次题目集进行综合性总结，我学到了很多关于编程和软件开发的重要知识和技能。以下是我的总结：
-
学习收获： 通过完成三次题目集，我深入了解了面向对象编程语言（java）的基础知识，包括字符和字符串操作、类与对象、算法等方面。我学会了如何解决问题、优化代码以及进行代码调试。这些都是我在软件开发中必不可少的技能。
-
进一步学习和研究： 尽管我在本阶段取得了一些进步，但我也意识到自己还有很多需要进一步学习和研究的地方。例如，我希望能够深入学习算法和数据结构，以提高自己的编程能力和解决问题的能力。此外，我还希望学习更多关于软件工程和系统设计方面的知识，以便能够更好地设计和开发复杂的软件系统。
-
改进建议：
-
教师： 希望教师能够提供更多的指导和支持。
-
作业： 建议作业设计能够更加渐变灵活，既能够巩固基础知识，又能够提高解决问题的能力。
-
实验： 希望实验内容能够更加贴近课程内容，能够帮助学生将理论知识应用到实际项目中。
-
课上及课下组织方式： 建议课堂教学能够更加互动和灵活，充分调动学生的学习积极性和主动性。
-
在未来，我希望能够进一步学习算法和数据结构，提高自己的编程水平。
总的来说，我认为本阶段的学习给我带来了很多启发和提高，我会继续努力学习，提高自己的专业水平。
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