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Author: basahota

qa/Java8CommonProgrammingQA.java

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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);
+
+    }
+
+
+}

qa/Student.java

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+package com.interview.qa;
+
+import java.util.List;
+import java.util.Objects;
+
+public class Student {
+
+    private int id;
+    private String firstName;
+    private int age;
+    private String gender;
+    private String dept;
+    private String city;
+    private int rank;
+    private List<String> contacts;
+
+    public Student(int id, String firstName, int age, String gender, String dept, String city, int rank, List<String> contacts) {
+        this.id = id;
+        this.firstName = firstName;
+        this.age = age;
+        this.gender = gender;
+        this.dept = dept;
+        this.city = city;
+        this.rank = rank;
+        this.contacts = contacts;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public void setFirstName(String firstName) {
+        this.firstName = firstName;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public void setAge(int age) {
+        this.age = age;
+    }
+
+    public String getGender() {
+        return gender;
+    }
+
+    public void setGender(String gender) {
+        this.gender = gender;
+    }
+
+    public String getDept() {
+        return dept;
+    }
+
+    public void setDept(String dept) {
+        this.dept = dept;
+    }
+
+    public String getCity() {
+        return city;
+    }
+
+    public void setCity(String city) {
+        this.city = city;
+    }
+
+    public int getRank() {
+        return rank;
+    }
+
+    public void setRank(int rank) {
+        this.rank = rank;
+    }
+
+    public List<String> getContacts() {
+        return contacts;
+    }
+
+    public void setContacts(List<String> contacts) {
+        this.contacts = contacts;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Student student = (Student) o;
+        return id == student.id && age == student.age && rank == student.rank && Objects.equals(firstName, student.firstName) && Objects.equals(gender, student.gender) && Objects.equals(dept, student.dept) && Objects.equals(city, student.city) && Objects.equals(contacts, student.contacts);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, firstName, age, gender, dept, city, rank, contacts);
+    }
+
+    @Override
+    public String toString() {
+        return "Student{" +
+                "id=" + id +
+                ", firstName='" + firstName + '\'' +
+                ", age=" + age +
+                ", gender='" + gender + '\'' +
+                ", dept='" + dept + '\'' +
+                ", city='" + city + '\'' +
+                ", rank=" + rank +
+                ", contacts=" + contacts +
+                '}';
+    }
+}