ClassRoll 和 Constructor 方法

Question

public class Exams {

private int score1 = 0;

private int score2 = 0;

private int score3 = 0;

 public void setScore1(int sc){
    score1 = sc;
}

public void setScore2(int sc){
    score2 = sc;
}

public void setScore3(int sc){
    score3 = sc;
}
public int getScore1(){
    return score1;
}

public int getScore2(){
    return score2;
}

public int getScore3(){
    return score3;
}

public String toString(){
    return String.format("%-10s %-10s %4.2f\n", score1, score2, score3);

}

}

public class Student {

private String fName;

private String lName;

private Exams scores;

Student(String fn, String ln) {
    fName = fn;
    lName = ln;
    scores = new scores();

}

public void setScore1(int sc) {
    scores.setScore1(sc);

}

public void setScore2(int sc) {
     scores.setScore2(sc);

}

public void setScore3(int sc) {
     scores.setScore3(sc);

}


public String toSring(){
    return String.format("%-10s %-10s %4.2f\n", fName, lName, scores);
}

public double getAverage(){

}

public int compareTo(Student s){
    String name1 = lName + "  " + fName;
    String name2 = s.lName + "  " + s.fName;

    return ((lName + "  " + fName).compareTo(s.lName + "  " + s.fName));
}

}

public class ClassRoll {

private ArrayList<Student> students = new ArrayList<Student>();
private String title;
private String filename = "data.txt";

ClassRoll(String f) {
    Scanner kb = new Scanner(System.in);
    String inpFileName = kb.next();
    File inpFile = new File(inpFileName);
    Student s = new Student(fName, lName);

}

void Remove() {
    Scanner kb = new Scanner(System.in);

    System.out.println("What is the Student's first name?");
    String fName = kb.next();

    System.out.println("What is the Student's last name?");
    String lName = kb.next();

    Student s = new Student(fName, lName);

    for (int i = 0; i < students.size(); i++) {
        if (s.compareTo(students.get(i)) == 0) {
            students.remove(i);

        } else {
            System.out.println("Error: Student is not in Class");
        }

    }

}

void Display() {

}

void Add() {
    Scanner kb = new Scanner(System.in);

    System.out.println("What is the Student's first name?");
    String fName = kb.next();

    System.out.println("What is the Student's last name?");
    String lName = kb.next();

    System.out.println("What is the Student's first score?");
    int score1 = kb.nextInt();

    System.out.println("What is the Student's second score?");
    int score2 = kb.nextInt();

    System.out.println("What is the Student's third score?");
    int score3 = kb.nextInt();

    Student s = new Student(fName, lName);

    for (int i = 0; i < students.size(); i++) {
        if (s.compareTo(students.get(i)) == 0) {
            System.out.println("Student already in class");
        } else {
            students.add(s);
        }
    }
}

void changeScore1() {
    Scanner kb = new Scanner(System.in);

    System.out.println("What is the Student's first name?");
    String fName = kb.next();

    System.out.println("What is the Student's last name?");
    String lName = kb.next();

    System.out.println("What is the Student's first score?");
    int score1 = kb.nextInt();

    Student s = new Student(fName, lName);

    for (int i = 0; i < students.size(); i++) {
        if (s.compareTo(students.get(i)) == 0) {
            s.setScore1(i);
        } else {
            System.out.println("Error: Student is not in Class");
        }

    }

}

void changeScore2() {
    Scanner kb = new Scanner(System.in);

    System.out.println("What is the Student's first name?");
    String fName = kb.next();

    System.out.println("What is the Student's last name?");
    String lName = kb.next();

    System.out.println("What is the Student's first score?");
    int score1 = kb.nextInt();

    Student s = new Student(fName, lName);

    for (int i = 0; i < students.size(); i++) {
        if (s.compareTo(students.get(i)) == 0) {
            s.setScore2(i);
        } else {
            System.out.println("Error: Student is not in Class");
        }

    }

}

void changeScore3() {
    Scanner kb = new Scanner(System.in);

    System.out.println("What is the Student's first name?");
    String fName = kb.next();

    System.out.println("What is the Student's last name?");
    String lName = kb.next();

    System.out.println("What is the Student's first score?");
    int score1 = kb.nextInt();

    Student s = new Student(fName, lName);

    for (int i = 0; i < students.size(); i++) {
        if (s.compareTo(students.get(i)) == 0) {
            s.setScore3(i);
        } else {
            System.out.println("Error: Student is not in Class");
        }

    }

}

public void sortAverage() {
    for (int i = 0; i < students.size() - 1; i++) {
        for (int j = i + 1; j < students.size(); j++) {
            Student s1 = (Student) students.get(i);
            Student s2 = (Student) students.get(j);
            if (s1.getAverage() < s2.getAverage()) {
                students.set(i, s2);
                students.set(j, s1);
            }
        }
    }
}

public void sortNames() {
    for (int i = 0; i < students.size() - 1; i++) {
        for (int j = i + 1; j < students.size(); j++) {
            Student s1 = (Student) students.get(i);
            Student s2 = (Student) students.get(j);
            if (s1.compareTo(s2) > 0) {
                students.set(i, s2);
                students.set(j, s1);
            }
        }
    }
}

public void save(){

}

}

我有一个包含几个不同课程的程序。在声明私有变量之后的 classroll 类中，我必须创建一个 classroll 构造函数“ClassRoll(String f)”，假设为.....

从输入文件 f 中读取班级卷数据，为每个学生创建学生对象并将它们添加到学生的 ArrayList 中。输入文件的第一行包含课程名称。每个学生的数据显示在一个单独的行中，由名字、姓氏、score1、score 2 和 score3 组成，至少用一个空格分隔。

我尽我最大的努力开始它，但我很困惑，不知道正确的制作方法。有人可以帮忙吗

谢谢

Answer 1

从输入文件f中读取班级卷数据，创建Student 每个学生的对象并将它们添加到 ArrayList 学生。

好的，所以基本上，我们必须从某个文件中获取学生的信息并将其添加到某个 ArrayList 中。好吧，让我们先创建一个 ArrayList 来存储东西。

ArrayList<Student> studentInfo = new ArrayList<Student>();

你已经有这个代码要从文件中读取：

Scanner kb = new Scanner(System.in);
String inpFileName = kb.next();
File inpFile = new File(inpFileName);

让我们继续……

输入文件的第一行包含课程标题。

所以kb.nextLine() 中的第一个元素是课程名称。这意味着我们必须从第二行开始添加学生数据，也就是跳过第一行。好吧....

每个学生的数据显示在单独的一行中，包括 名字、姓氏、score1、score 2 和 score3 以 at 分隔 至少一个空格。

所以基本上，如果我们设法从space 字符中分割行，我们就会得到数据。现在来实现这个：

让我们创建一个boolean 变量来检查它的第一行是否：

boolean firstLine = true; // True - because it starts from first line

是时候开始读行了......

String courseName = ""; //I'll just store in a string, use as you wish

while(kb.hasNextLine()){
    if(firstLine){
        courseName = kb.nextLine(); //Set courseName if its first line
        firstLine = false; // We have moved past first line
    }
    else{ // Otherwise get student data
        // Lets store the student data in a string. This is just one line.
        // Something like: "FirstName LastName score1 score2 score3"
        String studentData = kb.nextLine();

        // Now time to split up data (so we get names/scores separately)
        String[] stData = studentData.split("\\s"); //Remember they have spaces between them. \\s --> A pattern that matches one or more spaces
        //So we can use those to separate data

        // This is how String[] stData contains the student information:
        // stData[0] = first name of student
        // stData[1] = last name of student
        // stData[2] = score1
        // stData[3] = score2
        // stData[4] = score3
        // Use this data however you like

        //Now that we have separated data, lets add the student object to ArrayList since we got all details.
        studentInfo.add(new Student(stData[0], stData[1]);
        // This last line of code is probably not going to do the trick.
        // You may need to make changes to your code to do stuff
    }
}

无论如何，我已经告诉过你如何阅读问题以及如何继续。你有所有的字符串，名字，姓氏和分数。现在由您决定如何使用它们。虽然最后一行代码可能不适合你，但它提示继续。

休息一下，你应该先弄清楚自己，因为如果我做所有的功课就没有乐趣;）

Answer 2

您已将 SE 替换为 scire1,2,3

当您在 setter 方法中获得一个 var 时，需要将它放在您的类的属性中。

只需替换为以下代码：

public void setScore1(int sc){
       score1=sc;
    }

    public void setScore2(int sc){
        score2=sc;
    }

    public void setScore3(int sc){
        score3=sc;
    }