Filter Null dan Empty data
contoh filter data null dan empty di java 8 menggunakan Stream.filter(). filter() adalah method yang ada di class Stream. untuk kasus kali ini saya akan menggunakan sample data seperti ini
"Google", "Yahoo", "Reddit", null, ""Filter String null
untuk menghilangkan semua null bisa ikuti code berikut:
List<String> data = new ArrayList<>(Arrays.asList("Google", "Yahoo", "Reddit", null, ""));
data.stream()
.filter(Objects::nonNull)
.forEach(System.out::println);List<String> data = new ArrayList<>(Arrays.asList("Google", "Yahoo", "Reddit", null, ""));
List<String> data2 = data.stream()
.filter(Objects::nonNull)
.collect(Collectors.toList());
System.out.println(data2);result
[Google, Yahoo, Reddit, ]
Filter null dan String null
untuk menghilangkan semua null dan string kosong bisa ikuti code berikut:
List<String> data = new ArrayList<>(Arrays.asList("Google", "Yahoo", "Reddit", null, ""));
data.stream()
.filter(Objects::nonNull)
.filter(s -> !s.isEmpty())
.forEach(System.out::println);List<String> data = new ArrayList<>(Arrays.asList("Google", "Yahoo", "Reddit", null, ""));
List<String> data3 = data.stream()
.filter(Objects::nonNull)
.filter(s -> !s.isEmpty())
.collect(Collectors.toList());
System.out.println(data3);result
Google Yahoo Reddit
Filter dan collect
untuk melakukan filter String di bawah dari 6 bisa ikuti code berikut
List<String> data = new ArrayList<>(Arrays.asList("Google", "Yahoo", "Reddit", null, ""));
List<String> data3 = data.stream()
.filter(Objects::nonNull)
.filter(s -> !s.isEmpty())
.filter(s -> s.length() >= 6)
.collect(Collectors.toList());
System.out.println(data3);result
[Google, Reddit]
Filter number
untuk melakukan filter Number bisa ikuti code berikut
List<String> numbers = Arrays.asList("1", "2", "3", "4", "5", "6");
System.out.println("original list: " + numbers);
List<Integer> even = numbers.stream()
.map(s -> Integer.valueOf(s))
.filter(number -> number % 2 == 0)
.collect(Collectors.toList());
System.out.println("processed list, only even numbers: " + even);result
original list: [1, 2, 3, 4, 5, 6] processed list, only even numbers: [2, 4, 6]
Filter number with pojo
pojo java
public class Employee {
private int id;
private String name;
private int age;
private long salary;
private String gender;
private String deptName;
private String city;
private int yearOfJoining;
public Employee(int id, String name, int age, long salary, String gender, String deptName, String city,
int yearOfJoining) {
this.id = id;
this.name = name;
this.age = age;
this.salary = salary;
this.gender = gender;
this.deptName = deptName;
this.city = city;
this.yearOfJoining = yearOfJoining;
}
public long getSalary() {
return salary;
}
public int getExperience() {
return Calendar.getInstance().get(Calendar.YEAR) - yearOfJoining;
}
public String getDeptName() {
return deptName;
}
public int getAge() {
return age;
}
public String getGender() {
return gender;
}
public String getOrganization() {
return deptName;
}
@Override
public String toString() {
return "Employee{" +
"id=" + id +
", name='" + name + '\'' +
", age=" + age +
", salary=" + salary +
", gender='" + gender + '\'' +
", deptName='" + deptName + '\'' +
", city='" + city + '\'' +
", yearOfJoining=" + yearOfJoining +
'}';
}untuk melakukan filter nilai tertinggi bisa ikuti code berikut
List<Employee> employees = Arrays.asList(
new Employee(1, "John", 25, 5000, "Male", "IT", "London", 2010),
new Employee(2, "Jane", 30, 6000, "Female", "HR", "Paris", 2015),
new Employee(3, "Mike", 35, 7000, "Male", "Finance", "Berlin", 2020)
);
long highSalary = employees.stream()
.mapToLong(Employee::getSalary)
.max()
.orElse(0);
System.out.println(highSalary);result
7000
untuk melakukan filter nilai tertinggi kedua bisa ikuti code berikut
List<Employee> employees = Arrays.asList(
new Employee(1, "John", 25, 5000, "Male", "IT", "London", 2010),
new Employee(2, "Jane", 30, 6000, "Female", "HR", "Paris", 2015),
new Employee(3, "Mike", 35, 7000, "Male", "Finance", "Berlin", 2020)
);
long highSalary = employees.stream()
.mapToLong(Employee::getSalary)
.boxed()
.distinct()
.sorted(Comparator.reverseOrder())
.skip(1)
.findFirst()
.orElse(0L);
System.out.println(highSalary);result
6000
untuk melakukan mengurutkan nilai bisa ikuti code berikut
List<Employee> employees = Arrays.asList(
new Employee(1, "John", 25, 5000, "Male", "IT", "London", 2010),
new Employee(2, "Jane", 30, 6000, "Female", "HR", "Paris", 2015),
new Employee(3, "John", 20, 3000, "Female", "HR", "Paris", 2015),
new Employee(4, "Mike", 35, 7000, "Male", "Finance", "Berlin", 2020));
List<Employee> sortedEmployees = employees.stream()
.sorted(Comparator.comparingLong(Employee::getSalary))
.collect(Collectors.toList());
sortedEmployees.forEach(System.out::println);result
Employee{id=3, name='John', age=20, salary=3000, gender='Female', deptName='HR', city='Paris', yearOfJoining=2015} Employee{id=1, name='John', age=25, salary=5000, gender='Male', deptName='IT', city='London', yearOfJoining=2010} Employee{id=2, name='Jane', age=30, salary=6000, gender='Female', deptName='HR', city='Paris', yearOfJoining=2015} Employee
untuk melakukan menjumlahkan nilai bisa ikuti code berikut
List<Employee> employees = Arrays.asList(
new Employee(1, "John", 25, 5000, "Male", "IT", "London", 2010),
new Employee(2, "Jane", 30, 6000, "Female", "HR", "Paris", 2015),
new Employee(3, "John", 20, 3000, "Female", "HR", "Paris", 2015),
new Employee(4, "Mike", 35, 7000, "Male", "Finance", "Berlin", 2020));
long totalSalary = employees.stream()
.mapToLong(Employee::getSalary)
.sum();
System.out.println("Total salary: " + totalSalary);result
Total salary: 21000
untuk melakukan mencari nilai rata-rata bisa ikuti code berikut
List<Employee> employees = Arrays.asList(
new Employee(1, "John", 25, 5000, "Male", "IT", "London", 2010),
new Employee(2, "Jane", 30, 6000, "Female", "HR", "Paris", 2015),
new Employee(3, "John", 20, 3000, "Female", "HR", "Paris", 2015),
new Employee(4, "Mike", 35, 7000, "Male", "Finance", "Berlin", 2020));
double averageSalary = employees.stream()
.mapToLong(Employee::getSalary)
.average()
.orElse(0);
System.out.println("Average salary: " + averageSalary);result
Average salary: 5250.0
untuk mencari high experience bisa ikuti code berikut
List<Employee> employees = Arrays.asList(
new Employee(1, "John", 25, 5000, "Male", "IT", "London", 2010),
new Employee(2, "Jane", 30, 6000, "Female", "HR", "Paris", 2015),
new Employee(3, "John", 20, 3000, "Female", "HR", "Paris", 2009),
new Employee(4, "Mike", 35, 7000, "Male", "Finance", "Berlin", 2020));
int maxExperience = employees.stream()
.mapToInt(Employee::getExperience)
.max()
.orElse(0);
List<Employee> mostExperiencedEmployees = employees.stream()
.filter(e -> e.getExperience() == maxExperience)
.collect(Collectors.toList());
mostExperiencedEmployees.forEach(System.out::println);result
Employee
untuk melakukan pengecekan karyawan yang di bidang HR bisa ikuti code berikut
List<Employee> employees = Arrays.asList(
new Employee(1, "John", 25, 5000, "Male", "IT", "London", 2010),
new Employee(2, "Jane", 30, 6000, "Female", "HR", "Paris", 2015),
new Employee(3, "John", 20, 3000, "Female", "HR", "Paris", 2009),
new Employee(4, "Mike", 35, 7000, "Male", "Finance", "Berlin", 2020));
boolean hasHREmployees = employees.stream()
.anyMatch(e -> "HR".equals(e.getDeptName()));
System.out.println("Are there any HR department employees? " + (hasHREmployees ? "Yes" : "No"));result
Are there any HR department employees? Yes
untuk mencari karyawang yang paling muda laki-laki bisa ikuti code berikut
List<Employee> employees = Arrays.asList(
new Employee(1, "John", 25, 5000, "Male", "IT", "London", 2010),
new Employee(2, "Jane", 30, 6000, "Female", "HR", "Paris", 2015),
new Employee(3, "John", 20, 3000, "Female", "HR", "Paris", 2009),
new Employee(4, "Mike", 35, 7000, "Male", "Finance", "Berlin", 2020));
Employee youngestFemale = employees.stream()
.filter(e -> "Male".equals(e.getGender()))
.min(java.util.Comparator.comparingInt(Employee::getAge))
.orElse(null);
System.out.println(youngestFemale);result
Employee
untuk melakukan count laki-laki dan perempuan di masing-masing department bisa ikuti code berikut
List<Employee> employees = Arrays.asList(
new Employee(1, "John", 25, 5000, "Male", "IT", "London", 2010),
new Employee(2, "Jane", 30, 6000, "Female", "HR", "Paris", 2015),
new Employee(3, "John", 20, 3000, "Female", "HR", "Paris", 2009),
new Employee(4, "Mike", 35, 7000, "Male", "Finance", "Berlin", 2020));
long malesInIT = employees.stream()
.filter(e -> "Male".equals(e.getGender()) && "IT".equals(e.getOrganization()))
.count();
long femalesInIT = employees.stream()
.filter(e -> "Female".equals(e.getGender()) && "IT".equals(e.getOrganization()))
.count();
long femalesInHR = employees.stream()
.filter(e -> "Female".equals(e.getGender()) && "HR".equals(e.getOrganization()))
.count();
System.out.println("Males in IT: " + malesInIT);
System.out.println("Females in IT: " + femalesInIT);
System.out.println("Females in HR: " + femalesInHR);result
Males in IT: 1 Females in IT: 0 Females in HR: 2
untuk melakukan group karyawan berdasarkan umur bisa ikuti code berikut
List<Employee> employees = Arrays.asList(
new Employee(1, "John", 25, 5000, "Male", "IT", "London", 2010),
new Employee(2, "Jane", 30, 6000, "Female", "HR", "Paris", 2015),
new Employee(3, "John", 20, 3000, "Female", "HR", "Paris", 2009),
new Employee(4, "Mike", 25, 7000, "Male", "Finance", "Berlin", 2020));
Map<Integer, List<Employee>> groupedByAge = employees.stream()
.collect(Collectors.groupingBy(Employee::getAge));
groupedByAge.forEach((age, empList) -> {
System.out.println("Age: " + age);
empList.forEach(System.out::println);
});result
Age: 20 Employee{id=3, name='John', age=20, salary=3000, gender='Female', deptName='HR', city='Paris', yearOfJoining=2009} Age: 25 Employee{id=1, name='John', age=25, salary=5000, gender='Male', deptName='IT', city='London', yearOfJoining=2010} Employee{id=4, name='Mike', age=25, salary=7000, gender='Male', deptName='Finance', city='Berlin', yearOfJoining=2020} Age: 30 Employee