我创建了一个三节课的课程。在第三个类中，我应该用“name”、“姓氏”、“code”和“age”值填充数组。但是，我的数组总是“null”，我无法填充它。谢谢大家的帮助。
头等舱：

import java.util.Scanner;

public class Main {
public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    String name, surname;
    int code, age, i=0, min=150;        

    System.out.println("How many teachers do you want to enter information?");
    i=in.nextInt();     

    for(int j=0; j<i; j++) 
    {
        System.out.println("Enter the teacher's name");
        name=in.next();
        System.out.println("Enter the teacher's surname");
        surname=in.next();
        System.out.println("Enter the teacher's code");
        code=in.nextInt();
        System.out.println("Enter the teacher's age");
        age=in.nextInt();

        Teacher d = new Teacher(name, surname, code, age);
        System.out.println(d.getCode());
        System.out.println(d.getSurname());
        System.out.println(d.getAge());

        University c = new University(name, surname, code, age);
        min=c.MinimumAge(age, min);

    }

    System.out.println(min);

}
}

二等舱：

public class Teacher
{
    protected String name;
    protected String surname;
    protected int code;
    protected int age;

    public Teacher(String name, String surname, int code, int age)
    {
        this.name=name;
        this.surname=surname;
        this.code=code;
        this.age=age;
    }

    public String getName()
    {
        return name;
    }

    public int getCode()
    {
        return code;
    }

    public String getSurname()
    {
        return surname;
    }

    public int getAge()
    {
        return age;
    }
}

第三类（我将“0”作为填充数组的位置，以便进行测试）：

public class University
{
    private Teacher[] array=new Teacher[4];;
    public University(String name, String surname, int code, int age)
    {
        array[0] = new Teacher(name, surname, code, age);
    }

    public int MinimumAge(int age, int min)
    {
        if (age<min)
            min=age;
        return min;
    }
}