如何在java中匹配另一个类中的arraylist数据

我开发了一个添加学生的学生类，在主类中，我使用arraylist显示所有已添加的学生。现在我做了一个注册班，我想匹配已输入注册班的ID，它是否匹配已添加的学生。我有问题，谁能告诉我怎么做。。。把我的代码放在下面

这是面班-

import java.util.*;


public class StudentRecordSystem {

static ArrayList<Student> list = new ArrayList<Student>();

public static void main(String[] args) {
    // TODO Auto-generated method stub


    String option;
    String option1 = "a";//initializing the option a from the main menu
    String option2 = "b";//initializing the option b from the main menu
    String option3 = "c";//initializing the option c from the main menu
    String option4 = "d";//initializing the option d from the main menu
    String option5 = "e";//initializing the option e from the main menu
    String option6 = "f";//initializing the option f from the main menu
    String option7 = "g";//initializing the option g from the main menu
    for(int i=1; i<2; i++)
    {
        System.out.println("========== Main Menu ==========");
        System.out.println("a)Student Admin \nb)Course Admin \nc)Staff Admin \nd)Exit");//printing the main menu options
        System.out.println("Your option: ");//asking the user for option to choose
        Scanner inputOption = new Scanner(System.in);
        option = inputOption.nextLine();//Taking user option

        if(option.equals(option1))
        {
            for(int l=1; l<2; l++){


                System.out.println("========== Student Admin Menu ==========");
                System.out.println("a)Add new Student \nb)List Enrolment Details \nc)Enrol Student \nd)Assign Exemption To a Student \ne)Process Payment \nf)Generate Report \ng)Go Back");//printing the main menu options
                System.out.println("Your option: ");//asking the user for option to choose
                option = inputOption.nextLine();//Taking user option
                if(option.equals(option1))
                {
                    Student st = new Student();
                    list.add(st);
                    l--;//continues the loop
                }
                if(option.equals(option2))
                {
                    for (Student st : list) {
                        System.out.println(st.toString());
                    }
                    l--;//continues the loop
                }
                if(option.equals(option3))
                {
                    String[] courseName = {"Java Programming","Object Oriented Design","Software Testing","J2EE","Software Architecture","Design Patterns"};
                    Course c = new Course(courseName);
                    //c.getCourseName();
                    System.out.println(Arrays.toString(c.getCourseName()));
                }
                if(option.equals(option4))
                {
                    System.out.println("Will assign exemption to a  student");
                }
                if(option.equals(option5))
                {
                    System.out.println("Will process payment for the student");
                }
                if(option.equals(option6))
                {   
                    System.out.println("Will Generate Report");
                }
            }
            if(option.equals(option7))
            {
                i--;//continues the loop
            }

        }
        else if(option.equals(option2))
        {
            System.out.println("Will go to course class");
            i--;//continues the loop
        }
        else if(option.equals(option3))
        {
            System.out.println("Will go to staff class");
            i--;//continues the loop
        }
        else if(option.equals(option4))
        {
            System.out.println("Thank You For Using This Program");
            System.exit(0);
        }
        else
        {
            System.out.println("Error:  The selected option is not Recognised. Try Again...");//Error message if wrong option has been entered
            i--;//continues the loop
        }
    }

}

}

这是注册班-

import java.util.ArrayList;
import java.util.Scanner;


public class Enrollment {

private String studentId;
private Scanner scan;



public Enrollment()
{
    scan = new Scanner(System.in);

    System.out.println("Please Enter The Student ID:");
    studentId = scan.next();


}



}

---

在主创建选项中，用户希望按ID搜索学生。 并创建EnrollmentClass的对象，并将Arraylist传递给构造函数。

---

在Enrollment类构造函数中，您需要迭代每个arrayList，直到找到id。

在

Enrollment

类中为

studentId

添加

getter

public String getStudentId(){
    return studentId;
}

在主类中，在初始化

列表

后创建

注册

对象

Enrollment enroll = new Enrollment();

迭代

ArrayList

以查找匹配项：

boolean isfound = false;
for(int i = 0; i < list.size(); i++){
    if(list.get(i).getStudentId().equals(enroll.getStudentId()){
        isfound = true;
    }
}
if(isfound){
    System.out.println("Student record found!");
}
else{
     System.out.println("No match found!");
}

boolean isfound=false；
对于（int i=0；i

当注册对象被创建时？它应该有学生列表，对吗？@user3515895不是

注册

类应该是一个对象定义吗？在你的主类中进行搜索可以，但我也放了一个else语句来显示是否没有记录或是否没有找到记录。但它只是打印消息匹配，不打印else语句

boolean isfound = false;
for(int i = 0; i < list.size(); i++){
    if(list.get(i).getStudentId().equals(enroll.getStudentId()){
        isfound = true;
    }
}
if(isfound){
    System.out.println("Student record found!");
}
else{
     System.out.println("No match found!");
}