// sample class to illustrate inheritance:  This class represents an undergraduate Student consisting of a name (first and last), major, gpa and hours earned.
// it has several constructors, accessors for all instance data, a private method to obtain the class rank, only used internally by toString, a toString and an equals
// plus mutators to change major and to add results of a new class to change gpa and hoursEarned
public class Student
{
	protected String firstName, lastName, major;
	protected double gpa;
	protected int hoursEarned;
	
	public Student()								// 0-arg constructor, no nothing about the student
	{
		firstName="unknown";
		lastName="unknown";
		major="unknown";
		gpa=0.0;
		hoursEarned=0;
	}
	
	public Student(String f, String l)				// assumed that this is a new student who has no major yet
	{
		firstName=f;
		lastName=l;
		major="unknown";
		gpa=0.0;
		hoursEarned=0;
	}

	public Student(String f, String l, String m)	// new student with no hours earned yet so no gpa
	{
		firstName=f;
		lastName=l;
		major=m;
		gpa=0.0;
		hoursEarned=0;
	}
	
	public Student(String f, String l, String m, double g, int h)	// student that we know all info on
	{
		firstName=f;
		lastName=l;
		major=m;
		gpa=g;
		hoursEarned=h;
	}
	
	public String getFirstName() { return firstName; }		// accessors for all 5 instance data
	public String getLastName() { return lastName; }
	public String getMajor() { return major; }
	public double getGpa() { return gpa; }
	public int getHours() { return hoursEarned; }
	
	public String toString()					// toString returns first and last name, major, gpa and class rank (freshman, sophomore, etc)
	{
		return firstName + " " + lastName + ": " + major + ", " + String.format("%5.3f", gpa)+ ", " + getRank();
	}
	
	private String getRank()					// private method only called internally to convert hours into class rank (String)
	{
		if(hoursEarned>=90) return "senior";
		else if(hoursEarned>=60) return "junior";
		else if(hoursEarned>=30) return "sophomore";
		else return "freshman";
	}
	
	public void changeMajor(String newm)		// mutator to change the major
	{
		major = newm;
	}
	
	public boolean equals(Student s)			// determine if this Student has the same info as the Student parameter s
	{
		return (firstName.equals(s.getFirstName())&&lastName.equals(s.getLastName())&&major.equals(s.getMajor())&&gpa==s.getGpa()&&hoursEarned==s.getHours());
	}
	
	public void newClass(char grade, int hours)	// add a new class' result to the student's hours and gpa
	{
		switch(grade) {							
			case 'A': gpa=(gpa*hoursEarned+hours*4)/(hoursEarned+hours); hoursEarned+=hours; break;
			case 'B': gpa=(gpa*hoursEarned+hours*3)/(hoursEarned+hours); hoursEarned+=hours; break;
			case 'C': gpa=(gpa*hoursEarned+hours*2)/(hoursEarned+hours); hoursEarned+=hours; break;
			case 'D': gpa=(gpa*hoursEarned+hours*1)/(hoursEarned+hours); hoursEarned+=hours; break;
			case 'F': gpa=(gpa*hoursEarned+hours*0)/(hoursEarned+hours); hoursEarned+=hours; break;
			default: System.out.println("Error, " + grade + " is not a legal grade");			// if not A, B, C, D, F, then illegal grade, do not change anything
		}
	}
}