MergingCustomObjects.java

package StreamExamples;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.stream.Stream;

import StudentClass.Student;

public class MergingCustomObjects 
{
	public static void main(String[] args)
	{
		
        Stream<Student> stream1 = Stream.of(new Student(1,"Ram"),new Student(2,"Arjun"),new Student(3,"Kavi"),new Student(4,"Sanju"),new Student(5,"Ajay"));
        Stream<Student> stream2 = Stream.of(new Student(6,"Raguram"),new Student(7,"Arun"),new Student(8,"KavinKumar"),new Student(9,"Sam"),new Student(10,"Akash"));
		Stream.concat(stream1, stream2)
                .filter(distinctByKey(Student::getName)).forEach(e->System.out.print(e+" "));
	
	}
	
	public static <T> Predicate<T> distinctByKey(Function<? super T, Object> keyExtractor)
    {
        Map<Object, Boolean> map = new ConcurrentHashMap<>();
        return t -> map.putIfAbsent(keyExtractor.apply(t), Boolean.TRUE) == null;
    }
}