toString method
A string representation of this object.
Some classes have a default textual representation,
often paired with a static parse function (like int.parse).
These classes will provide the textual representation as
their string representation.
Other classes have no meaningful textual representation
that a program will care about.
Such classes will typically override toString to provide
useful information when inspecting the object,
mainly for debugging or logging.
Implementation
@override
String toString() => 'PerformanceGradesPerCourseData[name=$name, courseId=$courseId, numEnrollments=$numEnrollments, numPassed=$numPassed, avgGrade=$avgGrade]';