package com.pse;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.DoubleSummaryStatistics;
import java.util.List;
import java.util.Optional;
import java.util.stream.Collectors;
/**
* @author shailesh
*/
public class Java8Test {
static List<Employee> employeeList = new ArrayList<Employee>();
static {
employeeList.add(new Employee(111, "Jiya Brein", 32, "Female", "HR", 2011, 25000.0));
employeeList.add(new Employee(122, "Paul Niksui", 25, "Male", "Sales And Marketing", 2015, 13500.0));
employeeList.add(new Employee(133, "Martin Theron", 29, "Male", "Infrastructure", 2012, 18000.0));
employeeList.add(new Employee(144, "Murali Gowda", 28, "Male", "Product Development", 2014, 32500.0));
employeeList.add(new Employee(155, "Nima Roy", 27, "Female", "HR", 2013, 22700.0));
employeeList.add(new Employee(166, "Iqbal Hussain", 43, "Male", "Security And Transport", 2016, 10500.0));
employeeList.add(new Employee(177, "Manu Sharma", 35, "Male", "Account And Finance", 2010, 27000.0));
employeeList.add(new Employee(188, "Wang Liu", 31, "Male", "Product Development", 2015, 34500.0));
employeeList.add(new Employee(199, "Amelia Zoe", 24, "Female", "Sales And Marketing", 2016, 11500.0));
employeeList.add(new Employee(200, "Jaden Dough", 38, "Male", "Security And Transport", 2015, 11000.5));
employeeList.add(new Employee(211, "Jasna Kaur", 27, "Female", "Infrastructure", 2014, 15700.0));
employeeList.add(new Employee(222, "Nitin Joshi", 25, "Male", "Product Development", 2016, 28200.0));
employeeList.add(new Employee(233, "Jyothi Reddy", 27, "Female", "Account And Finance", 2013, 21300.0));
employeeList.add(new Employee(244, "Nicolus Den", 24, "Male", "Sales And Marketing", 2017, 10700.5));
employeeList.add(new Employee(255, "Ali Baig", 23, "Male", "Infrastructure", 2018, 12700.0));
employeeList.add(new Employee(266, "Sanvi Pandey", 26, "Female", "Product Development", 2015, 28900.0));
employeeList.add(new Employee(277, "Anuj Chettiar", 31, "Male", "Product Development", 2012, 35700.0));
}
public static void main(String[] args) {
// Query 3.1 : How many male and female employees are there in the organization?
employeeList.stream().collect(Collectors.groupingBy(Employee::getGender, Collectors.counting())).entrySet()
.forEach(System.out::println);
System.out.println();
// Query 3.2 : Print the name of all departments in the organization?
employeeList.stream().map(Employee::getDepartment).distinct().forEach(System.out::println);
System.out.println();
// Query 3.3 : What is the average age of male and female employees?
employeeList.stream()
.collect(Collectors.groupingBy(Employee::getGender, Collectors.averagingInt(Employee::getAge)))
.entrySet().forEach(System.out::println);
System.out.println();
// Query 3.4 : Get the details of highest paid employee in the organization?
Optional<Employee> employee = employeeList.stream()
.collect(Collectors.maxBy(Comparator.comparingDouble(Employee::getSalary)));
System.out.println(employee);
// Or
Optional<Employee> employee2 = employeeList.stream().max(Comparator.comparingDouble(Employee::getSalary));
System.out.println(employee2);
System.out.println();
// Query 3.5 : Get the names of all employees who have joined after 2015?
employeeList.stream().filter(e -> e.getYearOfJoining() > 2015).map(Employee::getName)
.forEach(System.out::println);
System.out.println();
// Query 3.6 : Count the number of employees in each department?
employeeList.stream().collect(Collectors.groupingBy(Employee::getDepartment, Collectors.counting())).entrySet()
.forEach(System.out::println);
System.out.println();
// Query 3.7 : What is the average salary of each department?
employeeList.stream()
.collect(
Collectors.groupingBy(Employee::getDepartment, Collectors.averagingDouble(Employee::getSalary)))
.entrySet().forEach(System.out::println);
System.out.println();
// Query 3.8 : Get the details of youngest male employee in the product
// development department?
Optional<Employee> youngestMaleEmployeeInProductDevelopmentWrapper = employeeList.stream()
.filter(e -> e.getGender().equals("Male") && e.getDepartment().equals("Product Development"))
.min(Comparator.comparingInt(Employee::getAge));
System.out.println(youngestMaleEmployeeInProductDevelopmentWrapper);
// Or
Optional<Employee> youngestMaleEmployeeInProductDevelopmentWrapper2 = employeeList.stream()
.filter(e -> e.getGender().equals("Male") && e.getDepartment().equals("Product Development"))
.collect(Collectors.minBy(Comparator.comparingInt(Employee::getAge)));
System.out.println(youngestMaleEmployeeInProductDevelopmentWrapper2);
System.out.println();
// Query 3.9 : Who has the most working experience in the organization?
Optional<Employee> mostWorkingExperienceEmployee = employeeList.stream()
.min(Comparator.comparingInt(Employee::getYearOfJoining));
System.out.println(mostWorkingExperienceEmployee);
// OR
Optional<Employee> mostWorkingExperienceEmployee2 = employeeList.stream()
.sorted(Comparator.comparingInt(Employee::getYearOfJoining)).findFirst();
System.out.println(mostWorkingExperienceEmployee2);
System.out.println();
// Query 3.10 : How many male and female employees are there in the sales and
// marketing team?
employeeList.stream().filter(e -> e.getDepartment().equals("Sales And Marketing"))
.collect(Collectors.groupingBy(Employee::getGender, Collectors.counting())).entrySet()
.forEach(System.out::println);
System.out.println();
// Query 3.11 : What is the average salary of male and female employees?
employeeList.stream()
.collect(Collectors.groupingBy(Employee::getGender, Collectors.averagingDouble(Employee::getSalary)))
.entrySet().forEach(System.out::println);
System.out.println();
// Query 3.12 : List down the names of all employees in each department?
employeeList.stream().collect(Collectors.groupingBy(Employee::getDepartment)).entrySet().forEach(e -> {
System.out.println(e.getKey());
for (Employee emp : e.getValue()) {
System.out.println(emp);
}
});
System.out.println();
// Query 3.13 : What is the average salary and total salary of the whole
// organization?
DoubleSummaryStatistics doubleSummaryStatics = employeeList.stream()
.collect(Collectors.summarizingDouble(Employee::getSalary));
System.out.println(doubleSummaryStatics.getAverage());
System.out.println(doubleSummaryStatics.getSum());
System.out.println();
// Query 3.14 : Separate the employees who are younger or equal to 25 years from
// those employees who are older than 25 years.
employeeList.stream().collect(Collectors.partitioningBy(e -> e.getAge() > 25)).entrySet()
.forEach(System.out::println);
System.out.println();
// Query 3.15 : Who is the oldest employee in the organization? What is his age
// and which department he belongs to?
employeeList.stream().max(Comparator.comparingInt(Employee::getAge)).ifPresent(System.out::println);
//Query 3.16 : Sort employee in descending order based on salary employeeList.stream() .sorted(Comparator.comparingLong(Employee::getSalary).reversed()) .collect(toList());
//Query 3.17 : Find 10th highest salary employee employeeList.stream() .sorted(Comparator.comparingLong(Employee::getSalary).reversed()) .skip(9) .limit(1) .collect(toList());
//Find max number in the list of integers
List<Integer> numbers = Arrays.asList(3, 2, 2, 3, 7, 3, 5);
Integer maxObj = numbers.stream().collect(Collectors.maxBy(Comparator.naturalOrder())).get();
System.out.println(maxObj);
//OR
Integer i = numbers.stream().sorted(Comparator.reverseOrder()).findFirst().get();
System.out.println(i);
//How do you find the frequency of element in an array
List<String> listOfStrings = Arrays.asList("Pen", "Eraser", "Note Book", "Pen", "Pencil", "Pen", "Note Book", "Pencil");
Map<String, Long> elementCountMap = listOfStrings.stream()
.collect(Collectors.groupingBy(Function.identity(), Collectors.counting()));
//Or
IntStream.of( 1, 2, 3, 2, 1, 2, 3, 4, 2, 2, 2 )
.boxed()
.collect( Collectors.groupingBy( Function.identity(), Collectors.counting() ) ).entrySet().forEach(System.out::println);
//Sum number in a list
List<Integer> integers = Arrays.asList(1, 2, 3, 4, 5);
Integer sum = integers.stream().mapToInt(Integer::intValue).sum();
//OR
integers.stream().collect(Collectors.summingInt(Integer::intValue));
//Or
integers.stream().reduce(0, Integer::sum);
//Find only duplicate numbers
List<Integer> numbers = Arrays.asList(new Integer[]{1,2,1,3,4,4});
numbers.stream().filter(i -> Collections.frequency(numbers, i) >1)
.collect(Collectors.toSet()).forEach(System.out::println);
//OR
List<Integer> duplicates = IntStream.of( 1, 2, 3, 2, 1, 2, 3, 4, 2, 2, 2 )
.boxed()
.collect( Collectors.groupingBy( Function.identity(), Collectors.counting() ) )
.entrySet()
.stream()
.filter( p -> p.getValue() > 1 )
.map( Map.Entry::getKey )
.collect( Collectors.toList() );
System.out.println(duplicates);
//Find distinct numbers in an array
int[] distinctArr = Arrays.stream(new int[] { 1, 2, 3, 2, 1, 2, 3, 4, 2, 2, 2 }).distinct().toArray();
Arrays.stream(distinctArr).forEach(System.out::println);
//Find distinct numbers in a list
Arrays.asList(new Integer[] { 1, 2, 3, 2, 1, 2, 3, 4, 2, 2, 2 }).stream()
.distinct().forEach(System.out::println);
//Sort a map based on value
Map<String, Integer> wordCounts = new HashMap<>();
wordCounts.put("USA", 100);
wordCounts.put("jobs", 200);
wordCounts.put("software", 50);
wordCounts.put("technology", 70);
wordCounts.put("opportunity", 200);
Map<String, Integer> sortedByCount = wordCounts.entrySet()
.stream()
.sorted(Map.Entry.comparingByValue())
.collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, (e1, e2) -> e1, LinkedHashMap::new));
}
}
class Employee {
int id;
String name;
int age;
String gender;
String department;
int yearOfJoining;
double salary;
public Employee(int id, String name, int age, String gender, String department, int yearOfJoining, double salary) {
this.id = id;
this.name = name;
this.age = age;
this.gender = gender;
this.department = department;
this.yearOfJoining = yearOfJoining;
this.salary = salary;
}
public int getId() {
return id;
}
public String getName() {
return name;
}
public int getAge() {
return age;
}
public String getGender() {
return gender;
}
public String getDepartment() {
return department;
}
public int getYearOfJoining() {
return yearOfJoining;
}
public double getSalary() {
return salary;
}
@Override
public String toString() {
return "Id : " + id + ", Name : " + name + ", age : " + age + ", Gender : " + gender + ", Department : "
+ department + ", Year Of Joining : " + yearOfJoining + ", Salary : " + salary;
}
}
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