Java 8 Distinct by property

Question

In Java 8 how can I filter a collection using the Stream API by checking the distinctness of a property of each object?

For example I have a list of

Answer 1

You can use the distinct(HashingStrategy) method in Eclipse Collections.

List persons = ...;
MutableList distinct =
    ListIterate.distinct(persons, HashingStrategies.fromFunction(Person::getName));

If you can refactor persons to implement an Eclipse Collections interface, you can call the method directly on the list.

MutableList persons = ...;
MutableList distinct =
    persons.distinct(HashingStrategies.fromFunction(Person::getName));

HashingStrategy is simply a strategy interface that allows you to define custom implementations of equals and hashcode.

public interface HashingStrategy
{
    int computeHashCode(E object);
    boolean equals(E object1, E object2);
}

Note: I am a committer for Eclipse Collections.