编写程序练习 List 集合的基本使用

编写程序练习 List 集合的基本使用

Student类：

public class Student {


    public String name;
    public double grade;
    
    public Student(String name,double grade) {
        this.name = name;
        this.grade = grade;
    }
    
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public double getGrade() {
        return grade;
    }
    public void setGrade(double grade) {
        this.grade = grade;
    }

    @Override
    public String toString() {
        return "学生信息-- 名字：" + name + ", 成绩：" + grade + "。\n";
    }
    
    
    
    
    
    
    
}

StudentManager类：

import java.util.ArrayList;


public class StudentManager {

    ArrayList<Student> list = new ArrayList<Student>();
    
    //添加学生
    public void addStudent(Student stu) {
        list.add(stu);
    }
    
    public Student queryStudent(String name) {
        int len = list.size();
        int i = 0;
        while(i<len) {
            Student stu = list.get(i);
            if(stu.getName().equals(name)) {
                return stu;  //结果返回指定名字的Student学生类实例对象
            }
            i++;
        }
        return null;  //表示没有查询到指定名字的学生           
    }
    
    public boolean removeStudent(String name) {
        int len = list.size();
        int i = 0;
        while(i<len) {
            Student stu = list.get(i);
            if(stu.getName().equals(name)) {
                list.remove(i);
                return true;  //删除成功
            }
            i++;
        }
        return false;  //表示删除失败    
    }
    
    public void statisticsStudentsGrade() {
        int len = list.size();
        double avg=0;
        double high=0;
        double low=list.get(0).getGrade();
        double total=0;
        double grade=0;
        
        int i = 0;
        while(i<len) {
            Student stu = list.get(i);
            grade = stu.getGrade();
            
            total += grade;
            if(grade>=high) {
                high = grade;
            }else if(grade<=low) {
                low = grade;
            }    
            i++;
        }
            
        System.out.println("学生共"+len+"人，最高分："+high
                +",最低分："+low+",平均分："+total/len);
        
    }
    
}

Test类：

public class Test {

    
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        StudentManager manager = new StudentManager();
        Student s1 = new Student("张三",100);
        Student s2 = new Student("李四",85);
        Student s3 = new Student("王五",96);
        
        
        manager.addStudent(s1);
        manager.addStudent(s2);
        manager.addStudent(s3);
        
        manager.statisticsStudentsGrade();
    }

}