Methods that return boolean values

Question

Okay, so my question is regarding boolean returns. For my Comp Sci homework, I have to make a course registration program using methods, and one of them is an add course method. Basically, you search for the class in a catalog, and if it matches you add it to the students schedule and return a boolean value of true. I did this, but for some reason it is giving me an error. Here is the code:

public static boolean addCourse(
    Course[] catalog,
    Course[] mySchedule,
    int myNumCourses,
    int dept,
    int courseNum)
{
    int j;
    int i;
    int k;
    int deptCat;
    int courseNumCat;
    Course courseAdd = null;
    char checkDay;
    int checkTime;



    if (mySchedule.length == myNumCourses) {
        return false;
    }
        for (i = 0 ; i < catalog.length ; i++) {
            Course course = catalog[i];
            deptCat = course.getDepartment();
            courseNumCat = course.getCourseNumber();
            if (deptCat == dept && courseNumCat == courseNum) {
                courseAdd = catalog[i];
                break;
            }
            else continue; }
        for (j = 0 ; j < myNumCourses ; j++) {
            if (mySchedule[j] == null) {
                mySchedule[j] = courseAdd;
                return true;
                }
                else continue;
                }

    for (k = 0 ; k < mySchedule.length ; k++) {
        Course course = mySchedule[k];
        if (course != null) {
            checkDay = course.getDay();
            checkTime = course.getPeriod();
            if (checkDay == courseAdd.getDay() && checkTime == courseAdd.getPeriod()) {
                return false;
            }
        }
        else continue;

    }







}

Why doesn't it recognize the boolean return values? Is it because I placed them inside a loop?

Answer 1

You need to place a return-statement at the end of your method, even if you might know it will never be reached (the compiler is not smart enough to know that, which explains the error).

For instance, even this will not compile:

public static boolean foo() {
    if (true)
        return true;
}

unless we add a final return statement. What you have is analogous.

Answer 2

There is nothing wrong with putting your return values in loops, however, the compiler sees no guarantee that this method will return a value and thus raises an error. At the very end of the method you need to return either true or false, whichever is most appropriate. All of your returns are within conditionals and therefor could fail to execute leaving your function with no return statement.