实验1中的Student类代码： StudentTest主类：

由于实际的代码未给出，但我可以根据描述概括出其实验1可能的实现方式：

### Student 类代码示例

public class Student {
    private String name;
    private int age;
    private double grade;
    private String id; // 可能的额外字段
    private String email; // 如果有5个参数，则这是另一个额外字段

    public Student(String name, int age, double grade) {
        this.name = name;
        this.age = age;
        this.grade = grade;
    }

    public Student(String name, int age, double grade, String id) {
        this(name, age, grade); // 调用三个参数的构造器
        this.id = id;
    }

    public Student(String name, int age, double grade, String id, String email) {
        this(name, age, grade, id); // 调用四个参数的构造器
        this.email = email;
    }

    // Getter 和 Setter 方法
    public void setName(String name) { ... }
    public String getName() { ... }
    
    public void setAge(int age) { ... }
    public int getAge() { ... }
    
    public void setGrade(double grade) { ... }
    public double getGrade() { ... }

    public String getId() { return id; }
    public void setId(String id) { this.id = id; }

    public String getEmail() { return email; }
    public void setEmail(String email) { this.email = email; }

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", grade=" + grade +
                (id != null ? ", id='" + id + '\'' : "") +
                (email != null ? ", email='" + email + '\'' : "") +
                '}';
    }
}

### StudentTest 主类代码示例

public class StudentTest {
    public static void main(String[] args) {
        Student student1 = new Student("Alice", 20, 3.8);
        System.out.println(student1);

        Student student2 = new Student("Bob", 22, 3.6, "B123");
        System.out.println(student2);

        Student student3 = new Student("Charlie", 21, 3.9, "C456", "charlie@example.com");
        System.out.println(student3);
    }
}

请注意这只是一个基于题目描述的例子，并非确切的答案。具体实现时应考虑更多细节。