I have an objects class that holds the properties title, director, genre, rating. I have created an arraylist and have filled it with instances of this base class
ArrayList<Movie> movieCatalog
I am wanting to sort this ArrayList in alphabetical order by the title property and change their positions within the ArrayList. From my research I understand I need to use a Comparator class but I am confused about how to do this.
You can create a custom comparator and than call the Collections.sort(movieCatalog,comparator); method.
E.g.
public static final Comparator<movieCatalog> movieComparator = new Comparator<movieCatalog>() {
public int compare(movieCatalog a1, movieCatalog a2) {
return a1.name.compareTo(a2.name);
}
};
Collections.sort(movieCatakig,movieComparator);
Collection.sort, and put the movieCatalog, and movieComparator, the arraylist is sorted for you. See: docs.oracle.com/javase/tutorial/collections/interfaces/…
Your Movie class needs to implement Comparable<Movie>. Then you need to implement the compareTo method, which in this case can just call the String class compareTo method.
int compareTo(Movie other) {
return this.title.compareTo(other.title);
}
After that, if movies is an ArrayList of movies, you can simply do
Collections.sort(movies);
