Author: TheTechFinanceGuy

Here in this code example we will go through the max, min and count operations which we can use as part of new functionality introduced by Java 8.

count() – Returns the count of elements in the stream.

max() – This method returns the max element of a stream. It returns an Optional. We should do a get() call on that to get the actual object.

min() – This method returns the max element of a stream. It returns an Optional. We should do a get() call on that to get the actual object.

import java.util.*;
import java.util.stream.*;

class Student {

    private String name;
    private int round;
    private int points;
    
    public Student(String name, int round, int points) {
        super();
        this.name = name;
        this.round = round;
        this.points = points;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getRound() {
        return round;
    }
    public void setRound(int round) {
        this.round = round;
    }
    public int getPoints() {
        return points;
    }
    public void setPoints(int points) {
        this.points = points;
    }
}

public class Java8GroupByExample {
    public static void main(String args[]) {
      
     List<Integer> numList = Java8GroupByExample.getNumbersList();
     Long count = numList.stream().count();
     System.out.println("The count is "+count);
     
     Integer max = numList.stream().max(Comparator.comparing(Integer::valueOf)).get();
     System.out.println("The max is "+max);
     
     Integer min = numList.stream().min(Comparator.comparing(Integer::valueOf)).get();
     System.out.println("The min is "+min);
     
     List<Student> studList = Java8GroupByExample.createStudList();
     
     Comparator<Student> comparator = Comparator.comparing(Student::getPoints);
     Student minStud = studList.stream().min(comparator).get();
     System.out.println("The student with min points is "+minStud.getName());
     
     Student maxStud = studList.stream().max(comparator).get();
     System.out.println("The student with max points is "+maxStud.getName());
      
    }
    
    private static List<Integer> getNumbersList(){
        
        List<Integer> list = new ArrayList<Integer>();
        list.add(5);
        list.add(12);
        list.add(9);
        list.add(15);
        list.add(25);
        list.add(4);
        
        return list;
    }
    
    public static List<Student> createStudList()
    {
        List<Student> studList=new ArrayList<Student>();
    
        Student s1=new Student("Nathan",1,500); 
        Student s2=new Student("Chris",1,1000);  
        Student s3=new Student("David",1,100);
        Student s4=new Student("James",1,300);
        Student s5=new Student("Mike",1,3000);
    
        studList.add(s1);
        studList.add(s2);
        studList.add(s3);
        studList.add(s4);
        studList.add(s5);
    
        return studList;
    }
    
}