Course.java

import java.util.concurrent.atomic.AtomicInteger;
import java.util.ArrayList;

public class Course {
    private static AtomicInteger nextId = new AtomicInteger();
    final int id;
    private ArrayList<Integer> availability = new ArrayList<Integer>(java.util.Arrays.asList(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11));
    private String code, title = null;
    private int credit=0, requiredSections=1;

    public Course(String code){
        constructor(code, null, 0, 1);
        id = nextId.incrementAndGet();
    }

    public Course(String code, String title){
        constructor(code, title, 0, 1);
        id = nextId.incrementAndGet();
    }

    public Course(String code, String title, int credit){
        constructor(code, title, credit, 1);
        id = nextId.incrementAndGet();
    }

    public Course(String code, String title, int credit, int requiredSections){
        constructor(code, title, credit, requiredSections);
        id = nextId.incrementAndGet();
    }

    private void constructor(String code, String title, int credit, int requiredSections){
        setCode(code);
        setTitle(title);
        setCredit(credit);
        setRequiredSections(requiredSections);
    }

    // setter methods
    public void setCredit(int arg){ credit = arg; }
    public void setRequiredSections(int arg){ requiredSections = arg; }
    public void setTitle(String arg){ title = arg; }
    public void addAvailability(int arg){ availability.add(arg); }
    public void setCode(String arg){
        if(!arg.equals(arg.split(" "))){
            String[] split = arg.split(" ");
            arg = "";
            for (String str : split)
                arg+=str;
        }
        code = arg.toUpperCase();
    }

    // getter methods
    public int getCredit(){ return credit; }
    public int getRequiredSections(){ return requiredSections; }
    public String getCode(){ return code; }
    public String getTitle(){ return title; }
    public ArrayList<Integer> getAvailability(){ return availability; }

    @Override
    public boolean equals(Object other) {
        if (!(other instanceof Course))
            return false;

        Course that = (Course) other;

        return this.code.equalsIgnoreCase(that.code);
    }

    public String toString(){
        String course = getCode() + " " + getTitle() + " " + getCredit();
        return course;
    }
}