Student

import java.text.DecimalFormat;
import java.util.Calendar;

public class Student {

    private static final int DEFAULT_VALUE_YOB = 2000;
    private static final double DEFAULT_VALUE_GRADE = 60;
    private static final int CURRENT_YEAR;

    static {
        // Set the current year value or just set is as final value 2020
        CURRENT_YEAR = Calendar.getInstance().get(Calendar.YEAR);
//      CURRENT_YEAR = 2020;
    }

    private final int id;
    private final String firstName;
    private final String lastName;

    private int YOB;
    private double grade;

    public Student(int id, String firstName, String lastName) {
        this.id = id;
        this.firstName = firstName;
        this.lastName = lastName;
        this.YOB = DEFAULT_VALUE_YOB;
        this.grade = DEFAULT_VALUE_GRADE;
    }

    // Method for manual testing purpose only. Should be replaced by test class StudentTest
    public static void main(String[] args) {
        Student student = new Student(1001, "SAMIR", "SALEM");
        student.setYOB(2002);
        student.setGrade(80);
        System.out.println(student); // Instead of using System.out.print() should use Logger class

        //todo Add other cases to test default value for YOB and grade
    }

    public int getId() {
        return id;
    }

    public String getFirstName() {
        return firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public int getYOB() {
        return YOB;
    }

    public void setYOB(int YOB) {
        boolean isYOBvalid = changeYOB(YOB);
        this.YOB = isYOBvalid ? YOB : DEFAULT_VALUE_YOB;
    }

    // In my opinion this method should be named: verifyYOB()
    private boolean changeYOB(int yob) {
        return (1940 <= YOB) && (YOB <= 2017);
    }

    public double getGrade() {
        return grade;
    }

    public void setGrade(double grade) {
        boolean isGradeValid = changeGrade(grade);
        this.grade = isGradeValid ? grade : DEFAULT_VALUE_GRADE;
    }

    // In my opinion this method should be named: verifyGrade()
    public boolean changeGrade(double g) {
        return (0 <= grade) && (grade <= 100);
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append("NAME=").append(this.firstName.toUpperCase());
        sb.append(" ").append(this.lastName.toUpperCase());
        sb.append(", ID=").append(this.id);
        sb.append(", age=").append(CURRENT_YEAR - this.YOB);
        sb.append(", grade=").append(removeTrailingZero(this.grade));
        return sb.toString();
    }

    private String removeTrailingZero(double grade) {
        DecimalFormat df = new DecimalFormat("###.#");
        return df.format(this.grade);
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        Student student = (Student) o;

        if (id != student.id) return false;
        if (YOB != student.YOB) return false;
        if (Double.compare(student.grade, grade) != 0) return false;
        if (!firstName.equals(student.firstName)) return false;
        return lastName.equals(student.lastName);
    }

    @Override
    public int hashCode() {
        int result;
        long temp;
        result = id;
        result = 31 * result + firstName.hashCode();
        result = 31 * result + lastName.hashCode();
        result = 31 * result + YOB;
        temp = Double.doubleToLongBits(grade);
        result = 31 * result + (int) (temp ^ (temp >>> 32));
        return result;
    }
}