» Duplicate Code and Ceremony in Java » Managed Chaos by Naresh Jain

Duplicate Code and Ceremony in Java

How would you kill this duplication in a strongly typed, static language like Java?

private int calculateAveragePreviousPercentageComplete() {
    int result = 0;
    for (StudentActivityByAlbum activity : activities)
        result += activity.getPreviousPercentageCompleted();
    return result / activities.size();
}
 
private int calculateAverageCurrentPercentageComplete() {
    int result = 0;
    for (StudentActivityByAlbum activity : activities)
        result += activity.getPercentageCompleted();
    return result / activities.size();
}
 
private int calculateAverageProgressPercentage() {
    int result = 0;
    for (StudentActivityByAlbum activity : activities)
        result += activity.getProgressPercentage();
    return result / activities.size();
}

Here is my horrible solution:

private int calculateAveragePreviousPercentageComplete() {
    return new Average(activities) {
        public int value(StudentActivityByAlbum activity) {
            return activity.getPreviousPercentageCompleted();
        }
    }.result;
}
 
private int calculateAverageCurrentPercentageComplete() {
    return new Average(activities) {
        public int value(StudentActivityByAlbum activity) {
            return activity.getPercentageCompleted();
        }
    }.result;
}
 
private int calculateAverageProgressPercentage() {
    return new Average(activities) {
        public int value(StudentActivityByAlbum activity) {
            return activity.getProgressPercentage();
        }
    }.result;
}
 
private static abstract class Average {
    public int result;
 
    public Average(List<StudentActivityByAlbum> activities) {
        int total = 0;
        for (StudentActivityByAlbum activity : activities)
            total += value(activity);
        result = total / activities.size();
    }
 
    protected abstract int value(StudentActivityByAlbum activity);
}

if this were Ruby

@activities.inject(0.0){ |total, activity| total + activity.previous_percentage_completed? } / @activities.size
@activities.inject(0.0){ |total, activity| total + activity.percentage_completed? } / @activities.size
@activities.inject(0.0){ |total, activity| total + activity.progress_percentage? } / @activities.size

or even something more kewler

average_of :previous_percentage_completed?
average_of :percentage_completed?
average_of :progress_percentage?
 
def average_of(message)
	@activities.inject(0.0){ |total, activity| total + activity.send message } / @activities.size
end

This entry was posted on Thursday, July 21st, 2011 at 5:07 PM and is filed under Agile, Code Smells, Java, Programming, Programming Languages. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.