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237 lines (211 loc) · 7.64 KB
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import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.*;
class Student {
private String name;
private int id;
private double grade;
public Student() {
name = "";
id = 0;
grade = 0.0;
}
public Student(String name, int id, double grade) {
this.name = name;
this.id = id;
this.grade = grade;
}
public String getName() {
return name;
}
public int getId() {
return id;
}
public double getGrade() {
return grade;
}
public void setName(String name) {
this.name = name;
}
public void setId(int id) {
this.id = id;
}
public void setGrade(double grade) {
this.grade = grade;
}
public String toString() {
return "Name=" + name + ", id=" + id + ", grade=" + grade + "]";
}
}
class StudentIO {
public static ArrayList<Student> readStudentData(String filename) {
ArrayList<Student> students = new ArrayList<>();
try {
Scanner scanner = new Scanner(new File(filename));
while (scanner.hasNextLine()) {
String fullname = scanner.next();
String id = scanner.next();
String grade = scanner.next();
students.add(new Student(fullname, Integer.parseInt(id), Double.parseDouble(grade)));
}
scanner.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
}
return students;
}
public void writeStudentData(String filename, ArrayList<Student> students) {
try {
PrintWriter writer = new PrintWriter(new File(filename));
for (Student student : students) {
writer.println(student.getName() + "\t" + student.getId() + "\t" + student.getGrade());
}
// calculate the average grade
double sum = 0;
for (Student student : students) {
sum += student.getGrade();
}
double average = sum / students.size();
writer.println("Average grade: " + average);
writer.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
}
class StudentManager {
public static void addStudent(ArrayList<Student> students) {
try {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter student name: ");
String name = scanner.next();
System.out.print("Enter student id: ");
String id = scanner.next();
System.out.print("Enter student grade: ");
String grade = scanner.next();
students.add(new Student(name, Integer.parseInt(id), Double.parseDouble(grade)));
scanner.close();
} catch (InputMismatchException e) {
System.out.println("Invalid input");
}
}
public static void deleteStudent(ArrayList<Student> students) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter student id: ");
int id = scanner.nextInt();
for (int i = 0; i < students.size(); i++) {
if (students.get(i).getId() == id) {
students.remove(i);
break;
}
}
scanner.close();
}
public static void updateStudent(ArrayList<Student> students) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter student id: ");
int id = scanner.nextInt();
for (Student student : students) {
if (student.getId() == id) {
System.out.print("Enter student name: ");
String name = scanner.next();
System.out.print("Enter student grade: ");
String grade = scanner.next();
student.setName(name);
student.setGrade(Double.parseDouble(grade));
break;
}
}
scanner.close();
}
public static void displayStudent(ArrayList<Student> students) {
for (Student student : students) {
System.out.println(student);
}
}
public static void sortStudentByName(ArrayList<Student> students) {
students.sort(new Comparator<Student>() {
@Override
public int compare(Student s1, Student s2) {
return s1.getName().compareTo(s2.getName());
}
});
}
public static void searchStudent(ArrayList<Student> students) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter student name: ");
String name = scanner.nextLine();
for (Student student : students) {
if (student.getName().equals(name)) {
System.out.println(student);
}
}
scanner.close();
}
}
class GradeManager {
public static void highestGrade(ArrayList<Student> students) {
double highest = 0;
for (Student student : students) {
if (student.getGrade() > highest) {
highest = student.getGrade();
}
}
System.out.println("Highest grade: " + highest);
}
public static void lowestGrade(ArrayList<Student> students) {
double lowest = 10.0;
for (Student student : students) {
if (student.getGrade() < lowest) {
lowest = student.getGrade();
}
}
System.out.println("Lowest grade: " + lowest);
}
public static void medianGrade(ArrayList<Student> students) {
ArrayList<Double> grades = new ArrayList<>();
for (Student student : students) {
grades.add(student.getGrade());
}
Collections.sort(grades);
int middle = grades.size() / 2;
if (grades.size() % 2 == 1) {
System.out.println("Median grade: " + grades.get(middle));
} else {
System.out.println("Median grade: " + (grades.get(middle - 1) + grades.get(middle)) / 2.0);
}
}
}
public class Exercise4 {
public static void main(String[] args) {
ArrayList<Student> students = StudentIO.readStudentData("src/Week5/grade.txt");
StudentIO studentIO = new StudentIO();
Scanner scanner = new Scanner(System.in);
while (true) {
System.out.println("1. Add student 2. Delete student 3. Update student");
System.out.println("4. Display student 5. Sort student by name 6. Search student");
System.out.println("7. Highest grade 8. Lowest grade 9. Median grade");
System.out.println(" 10. Exit");
System.out.print("Enter your choice: ");
int choice = scanner.nextInt();
switch (choice) {
case 1 -> StudentManager.addStudent(students);
case 2 -> StudentManager.deleteStudent(students);
case 3 -> StudentManager.updateStudent(students);
case 4 -> StudentManager.displayStudent(students);
case 5 -> StudentManager.sortStudentByName(students);
case 6 -> StudentManager.searchStudent(students);
case 7 -> GradeManager.highestGrade(students);
case 8 -> GradeManager.lowestGrade(students);
case 9 -> GradeManager.medianGrade(students);
case 10 -> {
scanner.close();
studentIO.writeStudentData("src/Week5/studentoutput.txt", students);
System.exit(0);
}
default -> System.out.println("Invalid choice");
}
}
}
}