[java] How to sort a List of objects by their date (java collections, List<Object>)

private List<Movie> movieItems = null;
public List<Movie> getMovieItems() {
    final int first = 0;
    if (movieItems == null) {
        getPagingInfo();
        movieItems = jpaController.findRange(new int[]{pagingInfo.getFirstItem(), pagingInfo.getFirstItem() + pagingInfo.getBatchSize()});
        Collections.sort(movieItems, new Comparator(){
           public int compare (Object o1, Object o2){
               Date d1 = movieItems.get(((Movie)o1).getMovieId()).getDate();
               Date d2 = movieItems.get(((Movie)o2).getMovieId()).getDate();
               if(d1.before(d2)){
                   movieItems.set(1, (Movie)o1);
                   movieItems.set(2, (Movie)o2);
               }
               return first;
           }
       });
    }
    return movieItems;
}

jpaController is bringing back 4 movies and is giving me the following

java.lang.ArrayIndexOutOfBoundsException: Array index out of range: 4 at java.util.Vector.get(Vector.java:694) at entitybeans.jsf.PeliculaController$1.compare(PeliculaController.java:260) at java.util.Arrays.mergeSort(Arrays.java:1270) at java.util.Arrays.sort(Arrays.java:1210) at java.util.Collections.sort(Collections.java:159) at entitybeans.jsf.PeliculaController.getPeliculaItems(PeliculaController.java:257) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at javax.el.BeanELResolver.getValue(BeanELResolver.java:302) at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:175) at com.sun.faces.el.FacesCompositeELResolver.getValue(FacesCompositeELResolver.java:72) at com.sun.el.parser.AstValue.getValue(AstValue.java:116) at com.sun.el.parser.AstValue.getValue(AstValue.java:163)....

You can use this:

Collections.sort(list, org.joda.time.DateTimeComparator.getInstance());

I'd add Commons NullComparator instead to avoid some problems...

In Java 8, it's now as simple as:

movieItems.sort(Comparator.comparing(Movie::getDate));

You're using Comparators incorrectly.

 Collections.sort(movieItems, new Comparator<Movie>(){
           public int compare (Movie m1, Movie m2){
               return m1.getDate().compareTo(m2.getDate());
           }
       });

Do not access or modify the collection in the Comparator. The comparator should be used only to determine which object is comes before another. The two objects that are to be compared are supplied as arguments.

Date itself is comparable, so, using generics:

class MovieComparator implements Comparator<Movie> {
    public int compare(Movie m1, Movie m2) {
       //possibly check for nulls to avoid NullPointerException
       return m1.getDate().compareTo(m2.getDate());
    }
}

And do not instantiate the comparator on each sort. Use:

private static final MovieComparator comparator = new MovieComparator();