调用对象方法没有得到预期的结果

Question

我有两个 .java 文件，一个是“蓝图”，另一个只包含主要方法。我遇到的问题是，我想打印与输入的数字相对应的字母。我让它对一个“学生”对象工作正常，但是当创建另一个“学生2”对象时，无论用户输入什么数字，每次都会打印字母“F”。请查看下面的代码以更好地理解。public class StudentRecordpublic String firstName;public String lastName;public int studentID;public int courseGradeOne;//create a constructor with no args.public StudentRecord(){}//end of constructor without args.public StudentRecord(String firstName, String lastName, int studentID, int courseGradeOne){    //initializing variables.    this.firstName = firstName;    this.lastName = lastName;    this.studentID = studentID;    this.courseGradeOne = courseGradeOne;}//end of constructor with args./*Setters & Getters for all 'fields'.*/public void setFirstName(String firstName){    firstName = firstName;}//end of setter firstName.public String getFirstName(){    return firstName;}//end of getter firstName.public void setLastName(String lastName){    lastName = lastName;}//end of setter lastName.public String getLastName(){    return lastName;}//end of getter lastName.public void setStudentID(int studentID){    studentID = studentID;}//end of setter studentID.public int getStudentID(){    return studentID;}//end of getStudentID.public void setCourseGradeOne(int courseGradeOne){    courseGradeOne = courseGradeOne;}//end of setter courseGradeOne.public int getCourseGradeOne(){    return courseGradeOne;}//end of getter courseGradeOne./*Decision statements to determine "letter grade".*/public char letterReturn(){    if(courseGradeOne >= 90)        return 'A';    else        if(courseGradeOne >= 80)            return 'B';        else            if(courseGradeOne >= 70)                return 'C';            else                if(courseGradeOne >= 60)                    return 'D';                else                    if(courseGradeOne >= 50)                        return 'E';                    else                        return 'F';}//end of letterReturn.

Answer 1

在 student2 的情况下，使用 getter/setter 方法会有所帮助

//creating student2 'object'.

StudentRecord student2 = new StudentRecord();

//ask information about student2.

System.out.println("What is your first name?");

String firstName = input.nextLine();

student2.setFirstName(firstName);

//print supplied information to user.

System.out.println("First Name: " + student2.getFirstName());

对其余部分做同样的事情，它应该可以解决。