Untitled

import java.util.Objects;

public class StudentManagement {

    static Student[] students = new Student[100];
    static int index = 0;
    static int indexGroup = 0;
    static String[] gs = new String[100];

    /**
     *An abstract class that represents an algorithm.
     *
     * @author zhangtj
     *
     * @version 1.0
     */
    public static boolean sameGroup(Student s1, Student s2) {
        if (Objects.equals(s1.getGroup(), s2.getGroup())) {
            return true;
        } else {
            return false;
        }
    }

    /**
     *An abstract class that represents an algorithm.
     *
     * @author zhangtj
     *
     * @version 1.0
     */
    public static boolean groupExist(String s) {
        for (int i = 0; i < 100; i++) {
            if (Objects.equals(s, gs[i])) {
                return true;
            }
        }
        return false;
    }

    /**
     *An abstract class that represents an algorithm.
     *
     * @author zhangtj
     *
     * @version 1.0
     */
    public static boolean sameStudent(Student s1, Student s2) {
        return Objects.equals(s1.getName(), s2.getName())
                && Objects.equals(s1.getGroup(), s2.getGroup())
                && Objects.equals(s1.getId(), s2.getId())
                && Objects.equals(s1.getEmail(), s2.getEmail());
    }

    /**
     *An abstract class that represents an algorithm.
     *
     * @author zhangtj
     *
     * @version 1.0
     */
    public void addStudent(Student newStudent) {
        boolean check = false;
        for (int i = 0; i < index; i++) {
            if (sameStudent(newStudent, students[i])) {
                check = true;
            }
        }
        if (!check) {
            if (index < students.length) {
                students[index] = newStudent;
                index++;
            } else {
                System.out.println("No more room for student");
            }
        }
    }

    /**
     *An abstract class that represents an algorithm.
     *
     * @author zhangtj
     *
     * @version 1.0
     */
    public String studentsByGroup() {
        String str = "";
        for (int i = 0; i < index; i++) {
            if (!groupExist(students[i].getGroup())) {
                String newGroup = students[i].getGroup();
                gs[indexGroup] = newGroup;
                indexGroup++;
            }
        }
        for (int i = 0; i < indexGroup; i++) {
            str = str + gs[i] + "\n";
            for (int j = 0; j < index; j++) {
                if (Objects.equals(gs[i], students[j].getGroup())) {
                    str = str + students[j].getInfor() + "\n";
                }
            }

        }
        return str;
    }

    /**
     *An abstract class that represents an algorithm.
     *
     * @author zhangtj
     *
     * @version 1.0
     */
    public void removeStudent(String id) {
        String tempId = "";
        boolean check = false;
        for (int i = 0; i < index; i++) {
            if (Objects.equals(students[i].getId(), id)) {
                tempId = students[i].getGroup();
                for (int j = i; j < index - 1; j++) {
                    students[j] = students[j + 1];
                }
                students[index - 1] = null;
                index = index - 1;
            }
        }
        for (int i = 0; i < index; i++) {
            if (Objects.equals(students[i].getGroup(), tempId)) {
                check = true;
            }
        }
        if (!check && indexGroup > 0) {
            for (int i = 0; i < indexGroup - 1; i++) {
                gs[i] = gs[i + 1];
            }
            gs[indexGroup - 1] = null;
            indexGroup = indexGroup - 1;
        }
    }

    /**
     *An abstract class that represents an algorithm.
     *
     * @author zhangtj
     *
     * @version 1.0
     */
    public static void main(String[] args) {

    }
}