Java Streams - Stream toArray(IntFunction generator) example

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Stream toArray(IntFunction<A[]> generator) returns an array containing the elements of this stream, using the provided generator function.

Syntax

toArray has the following syntax.

<A> A[] toArray(IntFunction<A[]> generator)

Example

The following example shows how to use toArray.

import java.util.List;
import java.time.LocalDate;
import java.time.Month;
import java.util.Arrays;
//w  w w.  j a  v a 2s . c o m
public class Main {
  public static void main(String[] args) {
    List<Employee> persons = Employee.persons();

    Employee[] men = persons.stream()
        .filter(p -> p.getGender() ==Gender.MALE)
        .toArray(Employee[]::new);

    System.out.println("After increasing the income: " + men);
  }
}
enum Gender {
  MALE, FEMALE
}

class Employee {
  private long id;
  private String name;
  private Gender gender;
  private LocalDate dob;
  private double income;

  public Employee(long id, String name, Gender gender, LocalDate dob,
      double income) {
    this.id = id;
    this.name = name;
    this.gender = gender;
    this.dob = dob;
    this.income = income;
  }

  public long getId() {
    return id;
  }

  public void setId(long id) {
    this.id = id;
  }

  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }

  public Gender getGender() {
    return gender;
  }

  public boolean isMale() {
    return this.gender == Gender.MALE;
  }

  public boolean isFemale() {
    return this.gender == Gender.FEMALE;
  }

  public void setGender(Gender gender) {
    this.gender = gender;
  }

  public LocalDate getDob() {
    return dob;
  }

  public void setDob(LocalDate dob) {
    this.dob = dob;
  }

  public double getIncome() {
    return income;
  }

  public void setIncome(double income) {
    this.income = income;
  }

  public static List<Employee> persons() {
    Employee ken = new Employee(1, "Jame", Gender.MALE, LocalDate.of(1970,
        Month.MAY, 4), 6123.0);
    Employee jeff = new Employee(2, "Jeff", Gender.MALE, LocalDate.of(1971,
        Month.JULY, 5), 7112.0);
    Employee donna = new Employee(3, "Jane", Gender.FEMALE, LocalDate.of(1972,
        Month.JULY, 9), 8712.0);
    Employee chris = new Employee(4, "Jodd", Gender.MALE, LocalDate.of(1973,
        Month.DECEMBER, 6), 1823.0);
    Employee laynie = new Employee(5, "Janey", Gender.FEMALE, LocalDate.of(1974,
        Month.DECEMBER, 3), 1234.0);
    Employee lee = new Employee(6, "Jason", Gender.MALE, LocalDate.of(1975, Month.MAY,
        8), 2412.0);

    // Create a list of persons
    List<Employee> persons = Arrays.asList(ken, jeff, donna, chris, laynie, lee);

    return persons;
  }

  @Override
  public String toString() {
    String str = String.format("(%s, %s, %s, %s, %.2f)", id, name, gender, dob,
        income);
    return str;
  }
}

The code above generates the following result.

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