首页 计算机与科学 Java 案例

# 需求

接口的应用案例：班级学生信息管理模块的开发

  • 请设计一个班级学生的信息管理模块：学生的数据有：姓名、性别、成绩
  • 功能一：要求打印出全班学生的信息
  • 功能二：要求打印出全班学生的平均成绩

注意！以上功能的业务实现是有多套方案的，如下：

  • 方案一：能打印出班级全部学生的信息；能打印班级全部学生的平均分
  • 方案二：能打印出班级全部学生的信息（包含男女人数）；能打印班级全部学生的平均分（要求是去掉最高分、最低分）

要求：系统可以支持灵活的切换这些实现方案

# 代码实现

# 学生类

描述学生相关信息

public class Student {
  private String name;
  private char sex;
  private double score;
  public Student() {
  }
  public Student(String name, char sex, double score) {
    this.name = name;
    this.sex = sex;
    this.score = score;
  }
  public String getName() {
    return name;
  }
  public void setName(String name) {
    this.name = name;
  }
  public char getSex() {
    return sex;
  }
  public void setSex(char sex) {
    this.sex = sex;
  }
  public double getScore() {
    return score;
  }
  public void setScore(double score) {
    this.score = score;
  }
}
# 接口
学生信息管理系统的两个功能
import java.util.ArrayList;
public interface StudentOperator {
  void printAllInfo(ArrayList<Student> students);
  void printAverageScore(ArrayList<Student> students);
}
# 实现类
方案一的实现类
import java.util.ArrayList;
public class StudentOperatorImpl1 implements StudentOperator {
  @Override
  public void printAllInfo(ArrayList<Student> students) {
    System.out.println("---------------全班学生信息---------------");
    for (int i = 0; i < students.size(); i++) {
      Student s = students.get(i);
      System.out.println("姓名：" + s.getName() + "，性别：" + s.getSex() + "，成绩：" + s.getScore());
    }
    System.out.println("----------------------------------------");
  }
  @Override
  public void printAverageScore(ArrayList<Student> students) {
    double allScore = 0.0;
    for (int i = 0; i < students.size(); i++) {
      Student s = students.get(i);
      allScore += s.getScore();
    }
    System.out.println("全班的平均分：" + allScore / students.size());
  }
}
方案二的实现类
import java.util.ArrayList;
public class StudentOperatorImpl2 implements StudentOperator {
  @Override
  public void printAllInfo(ArrayList<Student> students) {
    int girl_num = 0;
    int boy_num = 0;
    System.out.println("---------------全班学生信息---------------");
    for (int i = 0; i < students.size(); i++) {
      Student s = students.get(i);
      System.out.println("姓名：" + s.getName() + "，性别：" + s.getSex() + "，成绩：" + s.getScore());
      if (s.getSex() == '女') {
        girl_num++;
      } else {
        boy_num++;
      }
    }
    System.out.println("男生人数：" + boy_num + "，女生人数：" + girl_num);
    System.out.println("班级总人数：" + students.size());
    System.out.println("----------------------------------------");
  }
  @Override
  public void printAverageScore(ArrayList<Student> students) {
    double allScore = 0.0;
    double maxScore = students.get(0).getScore();
    double minScore = students.get(0).getScore();
    for (int i = 0; i < students.size(); i++) {
      Student s = students.get(i);
      allScore += s.getScore();
      if (s.getScore() > maxScore) maxScore = s.getScore();
      if (s.getScore() < minScore) minScore = s.getScore();
    }
    System.out.println("学生的最高分：" + maxScore + "，最低分：" + minScore);
    System.out.println("全班的平均分：" + (allScore - maxScore - minScore) / (students.size() - 2));
  }
}
# 班级管理类
import java.util.ArrayList;
public class ClassManager {
  private ArrayList<Student> students = new ArrayList<>();
  private StudentOperator op = new StudentOperatorImpl1();
  // private StudentOperator op = new StudentOperatorImpl2();
  public ClassManager() {
    students.add(new Student("呆呆", '女', 99));
    students.add(new Student("朱呆呆", '女', 96));
    students.add(new Student("朱朱", '男', 100));
    students.add(new Student("呆鸭", '女', 90));
    students.add(new Student("哈哈", '男', 80));
  }
  public void printInfo() {
    op.printAllInfo(students);
  }
  public  void printScore() {
    op.printAverageScore(students);
  }
}
# 测试类
public class Test {
  public static void main(String[] args) {
    ClassManager classManager = new ClassManager();
    classManager.printInfo();
    classManager.printScore();
  }
}