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package com.interview.qa;

import java.util.*;

import java.util.stream.Collectors;

import java.util.stream.Stream;

public class Java8CommonProgrammingQA {

public static void main(String[] args) {

List<Student> studentList = Stream.of(

new Student(1, "Rohit", 30, "Male", "Mechanical Engineering", "Mumbai", 122, Arrays.asList("+912632632782", "+1673434729929")),

new Student(2, "Pulkit", 56, "Male", "Computer Engineering", "Delhi", 67, Arrays.asList("+912632632762", "+1673434723929")),

new Student(3, "Ankit", 25, "Female", "Mechanical Engineering", "Kerala", 164, Arrays.asList("+912632633882", "+1673434709929")),

new Student(4, "Satish Ray", 30, "Male", "Mechanical Engineering", "Kerala", 26, Arrays.asList("+9126325832782", "+1671434729929")),

new Student(5, "Roshan", 23, "Male", "Biotech Engineering", "Mumbai", 12, Arrays.asList("+012632632782")),

new Student(6, "Chetan", 24, "Male", "Mechanical Engineering", "Karnataka", 90, Arrays.asList("+9126254632782", "+16736784729929")),

new Student(7, "Arun", 26, "Male", "Electronics Engineering", "Karnataka", 324, Arrays.asList("+912632632782", "+1671234729929")),

new Student(8, "Nam", 31, "Male", "Computer Engineering", "Karnataka", 433, Arrays.asList("+9126326355782", "+1673434729929")),

new Student(9, "Sonu", 27, "Female", "Computer Engineering", "Karnataka", 7, Arrays.asList("+9126398932782", "+16563434729929", "+5673434729929")),

new Student(10, "Shubham", 26, "Male", "Instrumentation Engineering", "Mumbai", 98, Arrays.asList("+912632646482", "+16734323229929")))

.collect(Collectors.toList());

// 1. Find the list of students whose rank is in between 50 and 100

List<Student> students = studentList.stream().filter(student -> student.getRank() > 50 && student.getRank() < 100)

.collect(Collectors.toList());

// System.out.println(students);

//2. Find the Students who stays in Karnataka and sort them by their names

List<Student> studentsByCity = studentList.stream().filter(student -> student.getCity().equals("Karnataka"))

.sorted(Comparator.comparing(Student::getFirstName,Comparator.reverseOrder())).collect(Collectors.toList());

// System.out.println(studentsByCity);

// 3. Find all departments names

List<String> deptNames = studentList.stream()

.map(Student::getDept)

.distinct()

.collect(Collectors.toList());

Set<String> deptNamesInSet = studentList

.stream().map(Student::getDept)

.collect(Collectors.toSet());

//System.out.println(deptNames);

//System.out.println(deptNamesInSet);

//4. Find all the contact numbers

List<String> contacts = studentList.stream()

.flatMap(student -> student.getContacts().stream())

.distinct()

.collect(Collectors.toList());

System.out.println(contacts);

//one2one-> map

//one2many-> flatmap

//5. Group The Student By Department Names

Map<String, List<Student>> studentMap = studentList.stream()

.collect(Collectors.groupingBy(Student::getDept));

// System.out.println(studentMap);

//6. Find the department who is having maximum number of students

Map.Entry<String, Long> results = studentList.stream()

.collect(Collectors.groupingBy(Student::getDept, Collectors.counting()))

.entrySet().stream().max(Map.Entry.comparingByValue()).get();

System.out.println(results);

//7. Find the average age of male and female students

Map<String, Double> avgStudents = studentList.stream()

.collect(Collectors

.groupingBy(Student::getGender,

Collectors.averagingInt(Student::getAge)));

//System.out.println(avgStudents);

//8. Find the highest rank in each department

Map<String, Optional<Student>> stdMap = studentList.stream()

.collect(Collectors.groupingBy(Student::getDept,

Collectors.minBy(Comparator.comparing(Student::getRank))));

// System.out.println(stdMap);

//9 .Find the student who has second rank

Student student = studentList.stream()

.sorted(Comparator.comparing(Student::getRank))

.skip(2)

.findFirst().get();

System.out.println(student);

}

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