如何打印学生信息？

Question

有没有一种方法可以打印我的学生提供的信息？ 我创建了一个包含有关课程的所有信息的服务类，我希望以一种非常简单的方式输入我的学生信息。

学生班：

public class student {

    //Fields
    private static String classNumber = "264";
    private static String className = "Transfiguration";
    private static String instructor = "Professor McGonagall";

    private int studentId;
    private String firstname;
    private String lastname;
    private String address;
    private String city;
    private String state;
    private String email;

    //Getters and setters

    static String getClassNumber(){
        return (classNumber);
    }
    static String getClassName(){
        return (className);
    }
    static String getInstructor(){
        return (instructor);
    }
    static void setClassName(String name){
        className = name;
    }

    int getStudentId(){
        return (studentId);
    }
    String getFirstName(){
        return (firstname);
    }
    String getLastName(){
        return (lastname);
    }
    String getAddress(){
        return (address);
    }
    String getCity(){
        return (city);
    }
    String getState(){
        return (state);
    }
    String getEmail(){
        return (email);
    }
    void setFirstName(String first) {
        this.firstname = first;
    }
    void setLastName(String last) {
        this.lastname = last;
    }
    void setAddress(String rua) {
        this.address = rua;
    }
    void setCity(String cidade) {
        this.city = cidade;
    }
    void setEmail(Sring correio) {
        this.email = correio;
     }
     //Contructors
    student(String la) {
        this.firstname = first;
        this.lastname = last;
        this.studentId += 1000;
    }
    student(String la, int id, String first, String last, String rua, String cidade, String correio) {

        this(la);

        this.address = rua;
        this.city = cidade;
        this.email = correio;

     }

    public String toString() {
        String data = "Course: " + classNumber + " " + className + 
                    "\t instructor: " + instructor + 
                    "\t Student Number: " + id + 
                    "\t Student Name: "  + firstname + " " + lastname + 
                    "\t Address: " + rua + cidade + 
                    "\t Email: " + correio;
        return (data);            
    }

}

学生测试课：

public class studentTest {
    public static void main (String [] args) {

        System.out.println("Course: " + student.getClassNumber() + student.getClassName());

        student a = new student("Kakashi", "Hatake", "W 69th st", "NY", "khsensei@ninja.com");
        student b = new student("Albus", "Dumbledore", "W 116th st", "NY", "princip-al@hogwarts.com" );
        student c = new student("Hyuk", "Jang", "321 Maple St", "NJ", "jh@actors.com");
        student d = new student("Michael", "Jackson", "543 thriller st", "NY", "mj@singer.com");
        student e = new student("Hamilton", "Alexander", "E 86th st", "NY", "justyouwait@broadway.com");

        String fname = a.firstname;
        System.out.println("First Name: " + fname);

        System.out.println(a.toString());
        System.out.println(b);
        System.out.println(c);
        System.out.println(d);
        System.out.println(e);
    }
}

我想做的是将所有信息打印在正确的位置，但是我一定忘记了一些非常严重的事情，我收到了错误消息。学生信息是否正确链接到第一堂课？

--

我收到的一些错误消息： “student.java:114: error: class studentTest is public, 应该在一个名为 studentTest.java 的文件中声明” - 对于这个，我之前尝试过，我可以将两个类放在同一个文件中，为什么不现在上班了吗？

有些符号找不到：

符号：变量优先 地点：班级学生 student.java:83：错误：找不到符号 this.lastname = last;

变量id、last、rua、cidade、和correio也会发生同样的情况。

构造函数也有错误 构造函数 student.student(String) 不适用 （实际参数列表和形式参数列表的长度不同） 构造函数 student.student(String, int, String, String, String, String) 不适用 student.java:124 错误：找不到适合学生的构造函数（字符串，字符串...）

Answer 1

我添加了 cmets 以更好地指出编译器抱怨的错误所在。这些都是非常常见的编译器消息，因此您应该花时间了解它们所指的内容并修复它们。你会一遍又一遍地看到它们。

public class student { //class names start with an uppercase letter

//Fields
private static String classNumber = "264";
private static String className = "Transfiguration";
private static String instructor = "Professor McGonagall";

private int studentId;
private String firstname;
private String lastname;
private String address;
private String city;
private String state;
private String email;

//Getters and setters

static String getClassNumber(){
    return (classNumber);
}
static String getClassName(){
    return (className);
}
static String getInstructor(){
    return (instructor);
}
static void setClassName(String name){
    className = name;
}

int getStudentId(){
    return (studentId);
}
String getFirstName(){
    return (firstname);
}
String getLastName(){
    return (lastname);
}
String getAddress(){
    return (address);
}
String getCity(){
    return (city);
}
String getState(){
    return (state);
}
String getEmail(){
    return (email);
}
void setFirstName(String first) {
    this.firstname = first;
}
void setLastName(String last) {
    this.lastname = last;
}
void setAddress(String rua) {
    this.address = rua;
}
void setCity(String cidade) {
    this.city = cidade;
}
void setEmail(Sring correio) { //You misspelled the type of the parameter
    this.email = correio;
 }
 //Contructors
student(String la) {
    this.firstname = first; //The parameter list to this constructor 
                            //only contains 'la', 'first' does not exist
    this.lastname = last; //The parameter list to this constructor 
                          //only contains 'la', 'last' does not exist
    this.studentId += 1000;
}
student(String la, int id, String first, String last, String rua, String cidade, String correio) {

    this(la);

    this.address = rua;
    this.city = cidade;
    this.email = correio;

 }

public String toString() {
    String data = "Course: " + classNumber + " " + className + 
                "\t instructor: " + instructor + 
                "\t Student Number: " + id + //id is the parameter in the 
                                             //constructor, not the private field name
                "\t Student Name: "  + firstname + " " + lastname + 
                "\t Address: " + rua + cidade + //rua and cidade are parameters in the 
                                             //constructor, not the private field names
                "\t Email: " + correio; //correio is the parameter in the 
                                        //constructor, not the private field name
    return (data);            
}

}

学生测试课：

public class studentTest { //classes start with a capital letter and belong in seprate files
public static void main (String [] args) {

    System.out.println("Course: " + student.getClassNumber() + student.getClassName());

    //Student's constructor requires 7 arguments of type String, int, String, String, String, String, String
    student a = new student("Kakashi", "Hatake", "W 69th st", "NY", "khsensei@ninja.com");
    student b = new student("Albus", "Dumbledore", "W 116th st", "NY", "princip-al@hogwarts.com" );
    student c = new student("Hyuk", "Jang", "321 Maple St", "NJ", "jh@actors.com");
    student d = new student("Michael", "Jackson", "543 thriller st", "NY", "mj@singer.com");
    student e = new student("Hamilton", "Alexander", "E 86th st", "NY", "justyouwait@broadway.com");

    String fname = a.firstname; //firstname is a private field
    System.out.println("First Name: " + fname);

    System.out.println(a.toString());
    System.out.println(b);
    System.out.println(c);
    System.out.println(d);
    System.out.println(e);
}
}

Answer 2

代码中的问题出在这一行：

String fname = a.firstname;

您实际上是在尝试访问私有字段：

String fname = a.getFirstName();

---

另一个问题是构造函数：

student(String la) {
        this.firstname = first;
        this.lastname = last;
        this.studentId += 1000;
    }

此上下文中不存在 first 和 last 变量。