显示java中一系列对象的最高值和最低值

Question

我必须从给定的用户输入中找到得分最高的学生和得分最低的学生。但我只得到最高分的学生，不能从中得到最低分的学生。

public class Student{

    public String name;
    public String id;
    public int score;
    public static int n;

    public Student(String initName,String initID,int initScore){

        initName=name;
        initID=id;
        initScore=score;
    }

    public Student (){

    }



    public static void main(String[] args) {

        System.out.println("Enter the number of students:");
        Scanner s1=new Scanner(System.in);

      
        Student.n=Integer.parseInt(s1.nextLine().trim());

        System.out.println("Enter the student name,id and score.");
        Scanner s2=new Scanner(System.in);

        Student st1=new Student();
        Student min=new Student(" "," ",100);
        Student max=new Student(" "," ",0);
        for(int i=0;i<Student.n;i++){
            st1.name=s2.next();
            st1.id=s2.next();
            st1.score=s2.nextInt();

            if(max.score<st1.score){
                max.score=st1.score;
                max.name=st1.name;
                max.id=st1.id;
            }
            if(min.score>st1.score){
                min.name=st1.name;
                min.score=st1.score;
                min.id=st1.id;
            }
        }
        System.out.println("the highest scoring student: "+max.name);
        System.out.println("the lowest scoring student: "+min.name);
        
       
    }
}

Answer 1

        initScore=score;

请在构造函数中修正以上行。

其实所有的赋值都不对：

    public Student(String initName,String initID,int initScore){

        initName=name;
        initID=id;
        initScore=score;
    }

应该改成

    public Student(String initName, String initId, int initScore) {
        name = initName;
        id = initId;
        score = initScore;
    }

更好

    public Student(String name, String id, int score) {
        this.name = name;
        this.id = id;
        this.score = score;
    }

由于score 在初始构造中没有分配，它被分配了一个默认值0 并因此影响min 计算。 （因为它已经在 min 假设分数是积极的）

它适用于max 计算，因为获得的分数将大于或等于0，并最终将直接更新score（假设只允许正分数）。

Answer 2

我发现您的代码中有很多问题，而且您似乎并不真正知道如何编码，这让我想建议您先阅读一些 Java 教程。

现在到你的代码：

• Student类的实现就是漏洞百出，没有封装，构造函数出错，不知道n是干什么用的

  public class Student {
  
      private String name;
      private String id;
      private int score;
  
      public Student(String initName, String initID, int initScore){
          this.name = initName;
          this.id = initID;
          this.score = initScore;
      }
  
      // declare getters such as these two
      public String getName() {
          return this.name;
      }
  
      public int getScore() {
          return this.score;
      }
  }
  

• 你的main 方法也有很多错误：你有 2 个Scanners，你没有初始化足够多的学生，你的迭代完全错误

  public static void main(String[] args) {
      Scanner s1 = new Scanner(System.in);
      // get number of students
      System.out.println("Enter the number of students:");
      int numberOfStudents = s1.nextInt();
      // initialize array of students
      Student[] array = new Student[numberOfStudents];
      for(int i = 0; i < numberOfStudents; i++) {
          // get name of the student
          System.out.println("Enter the student name:");
          String name = s1.nextLine();
          // get id of student
          System.out.println("Enter the student id:");
          String id = s1.nextLine();
          // get score of student
          System.out.println("Enter the student score:");
          int score = s1.nextInt();
          array[i] = new Student(name, id, score);
      }
      // now you have students input
      // it's time to find your student
      // set the lowest and highest student to first student
      Student min = array[0];
      Student max = array[0];
      for(int i = 1; i < numberOfStudents; i++) {
          if(min.getScore() > array[i]) {
              min = array[i];
          } else if(max.getScore() < array[i]) {
              max = array[i];
          }
      }
      System.out.println("the highest scoring student: "+max.getName());
      System.out.println("the lowest scoring student: "+min.getName());
  }
  

Answer 3

再次仔细检查代码：

    public Student(String initName,String initID,int initScore){

    initName=name;
    initID=id;
    initScore=score;
}

你收到了吗...？越野车构造函数。 代码应该是

    public Student(String initName,String initID,int initScore){

    name = initName;
    id = initID;
    score = initScore;
}