package students;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Collections;

import java.util.List;

public class Student {

private String name;

private double gpa;

private List<String> courses;

private Student(String name, double gpa, List<String> courses) {

if (!isValidStudent(name, gpa)) throw new IllegalArgumentException();

this.name = name;

this.gpa = gpa;

this.courses = new ArrayList<>(courses);

}

private Student(String name, double gpa, String ... courses) {

// public Student() {} // Ouch, this would leave things not fully validated

if (!isValidStudent(name, gpa)) throw new IllegalArgumentException();

this.name = name;

this.gpa = gpa;

// asList creates a "view" on an array...

// this.courses = Arrays.asList(courses);

// List.of creates a truly immutable list structure, but if the

// elements within it are mutable objects...

this.courses = List.of(courses);

}

public static boolean isValidStudent(String name, double gpa) {

return ((name != null) && (gpa >= 0 && gpa <= 4.0));

}

// factory (or a builder) can support pooling (making a pool of shared objects)

// without changing the callers

// can also support returning subtypes, e.g. "VIPStudent"

public static Student of(String name, double gpa, String ... courses) {

return new Student(name, gpa, courses);

}

public String getName() {

return name;

}

public double getGpa() {

return gpa;

}

public Student withGpa(double gpa) {

if (isValidStudent(this.name, gpa)) {

return new Student(this.name, gpa, this.courses);

} else {

throw new IllegalArgumentException("bad gpa");

}

}

public List<String> getCourses() {

// return Collections.unmodifiableList(courses);

return courses;

}

@Override

public String toString() {

return "Student{" +

"name='" + name + '\'' +

", gpa=" + gpa +

", courses=" + courses +

'}';

}

}