how can we write the Lambda expression statement
Collections.sort(list,(a1,a2) -> (a1.getName().compareTo(a2.getName())));
into method references?
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2 Answers
Collections.sort(list, Comparator.comparing(Item::getName));
Or better yet,
list.sort(Comparator.comparing(Item::getName));
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Remember, a lambda expression is basically the implementation of a single method defined by a functional interface.
Any method that has a matching signature (except method name), can be used by reference in place of a lambda expression.
In your case, it's the Comparator<? super T> interface and it's int compare(T o1, T o2) method, so any method that returns an int and takes two arguments of the type of the collection elements will do.
So, if your list is a List<Person>, any method like this will work, regardless of method name:
public static int xxx(Person p1, Person p2) { ... }
The method can have any visibility (public, private, ...) and doesn't have to be static.
