CODEWITHSUNDEEP
javalambdapredicatefunctional-interface
Narendra
Narendra

Reputation: 161

Java 8 Predicate to select an element from list based on element properties

There is a List Employee Objects, each employee object has property start date. Task is to select only one employee who has the earliest start date. I am trying to use Java 8 Predicate for this. So basically how can I compare list elements with each other in predicate ? And how can I do the same thing using lambda with Functional interface ?

Upvotes: 1

Views: 1278

Answers (2)

gnzlrm
gnzlrm

Reputation: 302

Java Predicates are based on the mathematical concept of a Predicate, which is a function F(x) that returns true or false based on some properties of x. Given that the function cannot be redefined while traversing the collection, it isn't probably the to-go option for finding the minimum or maximum of some Collection.

A recommended way of doing so using Java 8 would be using the min function included on Java Streams.

Employee oldestEmployee = employees.stream().min(Comparator.comparing(Employee::getStartDate)).get()

Upvotes: 1

yevgeniy.batulin
yevgeniy.batulin

Reputation: 186

Supposing you have Employee:

class Employee {
   private LocalDate startDate;
}

Constructor and getter are omitted. You can find the employee with the earliest startDate as follows:

Optional<Employee> min = list.stream()
            .min(Comparator.comparing(Employee::getStartDate));

Upvotes: 2

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