How to sort a List<Object> alphabetically using Object name field

Answer 1

Try this:

List< Object> myList = x.getName;
myList.sort(Comparator.comparing(Object::getName));

Answer 2

This is assuming a list of YourClass instead of Object, as explained by amit.

You can use this bit from the Google Guava library:

Collections.sort(list, Ordering.natural()
  .onResultOf(new Function<String,YourClass>() {
  public String call(YourClass o) {
     return o.getName();
  }))
  .nullsLast();

The other answers which mention Comparator are not incorrect, since Ordering implements Comparator. This solution is, in my opinion, a little easier, though it may be harder if you're a beginner and not used to using libraries and/or "functional programming".

Copied shamelessly from this answer on my own question.

Answer 3

public class ObjectComparator implements Comparator<Object> {

    public int compare(Object obj1, Object obj2) {
        return obj1.getName().compareTo(obj2.getName());
    }

}

Please replace Object with your class which contains name field

Usage:

ObjectComparator comparator = new ObjectComparator();
Collections.sort(list, comparator);

Answer 4

You can use sortThisBy() from Eclipse Collections:

MutableList<Campaign> list = Lists.mutable.empty();
list.sortThisBy(Campaign::getName);

If you can't change the type of list from List:

List<Campaign> list = new ArrayList<>();
ListAdapter.adapt(list).sortThisBy(Campaign::getName);

Note: I am a contributor to Eclipse Collections.

Answer 5

@Victor's answer worked for me and reposting it here in Kotlin in case useful to someone else doing Android.

if (list!!.isNotEmpty()) {
   Collections.sort(
     list,
     Comparator { c1, c2 -> //You should ensure that list doesn't contain null values!
     c1.name!!.compareTo(c2.name!!)
   })
}

Answer 6

If you are using a List<Object> to hold objects of a subtype that has a name field (lets call the subtype NamedObject), you'll need to downcast the list elements in order to access the name. You have 3 options, the best of which is the first:

1. Don't use a List<Object> in the first place if you can help it - keep your named objects in a List<NamedObject>
2. Copy your List<Object> elements into a List<NamedObject>, downcasting in the process, do the sort, then copy them back
3. Do the downcasting in the Comparator

Option 3 would look like this:

Collections.sort(p, new Comparator<Object> () {
        int compare (final Object a, final Object b) {
                return ((NamedObject) a).getName().compareTo((NamedObject b).getName());
        }
}