3、抽象类实现多态设计父类Student、子类小学生Pupil、中学生MiddleStudent、大学生Undergraduate。在文本框输入相关数据，点击按钮，分别输出：² 小学生的姓名、学生类型、平均成绩（语文、数学）；² 中学生的姓名、学生类型、平均成绩（语文、数学、英语）；² 大学生的姓名、学生类型、总学分（选修课和必修课）；² 总人数。（1）Student类（父类、抽象类）² 定义抽象属性Type（学生类型）、静态字段number（学生人数）；² 有参构造方法，设置姓名、年龄、统计学生人数；² 抽象方法total()求总分；² 成员方法getInfo()，输出学生姓名、年龄、根据学生类型求平均成绩。（2）子类Pupil、MiddleStudent、Undergraduate² 重写父类的抽象属性Type和抽象方法total()；² 定义有参构造方法，设置姓名、年龄、科目，调用父类的构造方法。

好的，我理解了你的问题。下面是对应的Java代码实现：

// Student类
public abstract class Student {
    protected String name;
    protected int age;
    protected String type;
    protected static int number = 0;
    
    public Student(String name, int age) {
        this.name = name;
        this.age = age;
        number++;
    }
    
    public abstract double total();
    
    public void getInfo() {
        System.out.println("姓名：" + this.name);
        System.out.println("年龄：" + this.age);
        System.out.println("类型：" + this.type);
    }
}

// Pupil类
public class Pupil extends Student {
    private double chineseScore;
    private double mathScore;
    
    public Pupil(String name, int age, double chineseScore, double mathScore) {
        super(name, age);
        this.type = "小学生";
        this.chineseScore = chineseScore;
        this.mathScore = mathScore;
    }
    
    @Override
    public double total() {
        return (this.chineseScore + this.mathScore) / 2;
    }
    
    @Override
    public void getInfo() {
        super.getInfo();
        System.out.println("平均成绩：" + this.total());
    }
}

// MiddleStudent类
public class MiddleStudent extends Student {
    private double chineseScore;
    private double mathScore;
    private double englishScore;
    
    public MiddleStudent(String name, int age, double chineseScore, double mathScore, double englishScore) {
        super(name, age);
        this.type = "中学生";
        this.chineseScore = chineseScore;
        this.mathScore = mathScore;
        this.englishScore = englishScore;
    }
    
    @Override
    public double total() {
        return (this.chineseScore + this.mathScore + this.englishScore) / 3;
    }
    
    @Override
    public void getInfo() {
        super.getInfo();
        System.out.println("平均成绩：" + this.total());
    }
}

// Undergraduate类
public class Undergraduate extends Student {
    private double requiredCredit;
    private double electiveCredit;
    
    public Undergraduate(String name, int age, double requiredCredit, double electiveCredit) {
        super(name, age);
        this.type = "大学生";
        this.requiredCredit = requiredCredit;
        this.electiveCredit = electiveCredit;
    }
    
    @Override
    public double total() {
        return this.requiredCredit + this.electiveCredit;
    }
    
    @Override
    public void getInfo() {
        super.getInfo();
        System.out.println("总学分：" + this.total());
    }
}

// 测试代码
public class Test {
    public static void main(String[] args) {
        Pupil pupil = new Pupil("Tom", 10, 90, 95);
        MiddleStudent middleStudent = new MiddleStudent("Jerry", 15, 85, 90, 95);
        Undergraduate undergraduate = new Undergraduate("Lucy", 20, 90, 20);
        
        pupil.getInfo();
        middleStudent.getInfo();
        undergraduate.getInfo();
        
        System.out.println("总人数：" + Student.number);
    }
}

以上代码实现了题目所要求的抽象类实现多态设计，可以根据输入的数据输出对应的学生信息，以及学生人数。