Stream filter(Predicate predicate) example
Description
Stream filter(Predicate<? super T> predicate)
returns a stream that match the given predicate.
Syntax
filter
has the following syntax.
Stream<T> filter(Predicate<? super T> predicate)
Example
import java.util.Arrays;
import java.util.List;
// www . ja v a2s . com
public class Main {
public static void main(String[] args) {
List<Integer> numberList = Arrays.asList(1,2,3,4,5);
numberList.stream()
.filter(n-> n % 2== 0)
.forEach(System.out::println);
}
}
The code above generates the following result.
Example 2
The following example shows how to use filter
.
import java.util.List;
import java.time.LocalDate;
import java.time.Month;
import java.util.Arrays;
//from w w w . ja v a 2s . c o m
public class Main {
public static void main(String[] args) {
List<Employee> persons = Employee.persons();
persons.stream()
.filter(Employee::isFemale)
.forEach(p -> p.setIncome(p.getIncome() * 1.10));
System.out.println("After increasing the income: " + persons);
}
}
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.