java - 如何将我在不同类中创建的列表数组引用到另一个 2

Question

这是我创建数组列表的地方

package sample;


import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.scene.Node;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
import javafx.scene.control.TextField;
import javafx.scene.control.Button;
import javafx.event.ActionEvent;
import sample.Data.Students;
import java.io.IOException;
import java.util.ArrayList;

public class StudentEnrollment {

    public static ArrayList<Students> SDetails=new ArrayList<Students>();


    public static String StuID="";


    @FXML
    private Button studentenrollmentnextbtn;

    @FXML
    private TextField studentenrollmentname;

    @FXML
    private TextField studentenrollmentid;

    @FXML
    private TextField studentenrollmentage;

    @FXML
    private TextField studentenrollmentnum;

    public void StudentEnroll(ActionEvent m)throws IOException{

        Students s=new Students();
        s.setSname(studentenrollmentname.getText());
        s.setSid(studentenrollmentid.getText());
        StuID=studentenrollmentid.getText();
        s.setSage(Integer.parseInt(studentenrollmentage.getText()));
        s.setSnumber(Integer.parseInt(studentenrollmentnum.getText()));
        SDetails.add(s);


        Parent root= FXMLLoader.load(getClass().getResource("AdminEnterDetails.fxml"));
        Scene scene = new Scene(root);
        Stage stage= (Stage)((Node)m.getSource()).getScene().getWindow();
        stage.setScene(scene);
        stage.show();
    }

}

这是我的学生类(class)

package sample.Data;

public class Students {

    private String Sid;
    private String Sname;
    private int Sage;
    private int Snumber;


    public String getSid() {
        return Sid;
    }

    public void setSid(String sid) {
        Sid = sid;
    }

    public String getSname() {
        return Sname;
    }

    public void setSname(String sname) {
        Sname = sname;
    }

    public int getSage() {
        return Sage;
    }

    public void setSage(int sage) {
        Sage = sage;
    }

    public int getSnumber() {
        return Snumber;
    }

    public void setSnumber(int snumber) {
        Snumber = snumber;
    }

}

这是我想使用数组列表的地方，我想在这里使用它，因为，我想检查我的数组列表是否为空，如果为空我想显示一条错误消息，如果它不为空我想搜索我在该数组列表中输入的ID

public class StudentLogin {

    StudentEnrollment = new StudentEnrollment();
    ArrayList<Students> list = number.getList();

    @FXML
    private Label error;
    @FXML
    private TextField studentuserid;
    @FXML
    private Button studentloginbtn;


    public void ViewbyStudent(ActionEvent e) throws IOException {

        if()
        for(Students m:StudentEnrollment.SDetails)
            if(Objects.equals(m.getSid(),studentuserid.getText())){

                Parent root= FXMLLoader.load(getClass().getResource("ViewStudentDetails.fxml"));
                Scene scene = new Scene(root);
                Stage stage= (Stage)((Node)e.getSource()).getScene().getWindow();
                stage.setScene(scene);
                stage.show();

            }else{
                error.setText("Student ID you entered is incorrec,\n or ID couldn't be found,PLEASE TRY AGAIN");
            }

    }
}

Answer 1

StudentEnrollment.SDetails.isEmpty();