编写一个Java程序， 用List集合管理学生对象。设计学生Student类和学生管理类StudentManager。Student类包含学号、姓名、上学期所学课程成绩（不少于3门）、总分。StudentManager类的功能包括添加学生、查询学生、删除学生、统计学生成绩等。分别用LinkedList和ArrayList集合来管理若干学生实例。另外还需要设计测试类Test来验证StudentManager的功能。

好的，我明白了。以下是对应的Java代码：

// 学生类
public class Student {
    private int id; // 学号
    private String name; // 姓名
    private List<Double> scores; // 上学期所学课程成绩
    private double totalScore; // 总分

    public Student(int id, String name, List<Double> scores) {
        this.id = id;
        this.name = name;
        this.scores = scores;
        this.totalScore = 0;
        for (Double score : scores) {
            this.totalScore += score;
        }
    }

    // 计算平均分
    public double getAverageScore() {
        return this.totalScore / this.scores.size();
    }

    // getter 和 setter
    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public List<Double> getScores() {
        return scores;
    }

    public void setScores(List<Double> scores) {
        this.scores = scores;
        this.totalScore = 0;
        for (Double score : scores) {
            this.totalScore += score;
        }
    }

    public double getTotalScore() {
        return totalScore;
    }

    public void setTotalScore(double totalScore) {
        this.totalScore = totalScore;
    }
}

// 学生管理类
public class StudentManager {
    private List<Student> students;

    public StudentManager() {
        this.students = new LinkedList<>(); // 或者 ArrayList
    }

    // 添加学生
    public void addStudent(Student student) {
        this.students.add(student);
    }

    // 查询学生
    public Student getStudent(int id) {
        for (Student student : this.students) {
            if (student.getId() == id) {
                return student;
            }
        }
        return null;
    }

    // 删除学生
    public void deleteStudent(int id) {
        Iterator<Student> iterator = this.students.iterator();
        while (iterator.hasNext()) {
            Student student = iterator.next();
            if (student.getId() == id) {
                iterator.remove();
                break;
            }
        }
    }

    // 统计学生成绩
    public double getAverageScore() {
        double totalScore = 0;
        int count = 0;
        for (Student student : this.students) {
            totalScore += student.getTotalScore();
            count += student.getScores().size();
        }
        return totalScore / count;
    }

    // getter 和 setter
    public List<Student> getStudents() {
        return students;
    }

    public void setStudents(List<Student> students) {
        this.students = students;
    }
}

// 测试类
public class Test {
    public static void main(String[] args) {
        Student s1 = new Student(1001, "张三", Arrays.asList(80.0, 85.0, 90.0));
        Student s2 = new Student(1002, "李四", Arrays.asList(75.0, 88.0, 92.0));
        Student s3 = new Student(1003, "王五", Arrays.asList(90.0, 91.0, 95.0));

        StudentManager manager = new StudentManager();
        manager.addStudent(s1);
        manager.addStudent(s2);
        manager.addStudent(s3);

        // 查询学生
        Student s = manager.getStudent(1002);
        System.out.println(s.getName() + "的平均分是：" + s.getAverageScore());

        // 删除学生
        manager.deleteStudent(1001);

        // 统计学生成绩
        System.out.println("所有学生的平均分是：" + manager.getAverageScore());
    }
}

以上代码使用List集合管理学生对象，Student类包含学号、姓名、上学期所学课程成绩（不少于3门）、总分。StudentManager类的功能包括添加学生、查询学生、删除学生、统计学生成绩等。分别用LinkedList和ArrayList集合来管理若干学生实例。另外还设计了测试类Test来验证StudentManager的功能。