//Practicing JavaStreams

package test;

import java.io.IOException;

import java.nio.file.Files;

import java.nio.file.Paths;

import java.util.Arrays;

import java.util.HashMap;

import java.util.IntSummaryStatistics;

import java.util.List;

import java.util.Map;

import java.util.stream.Collectors;

import java.util.stream.IntStream;

import java.util.stream.Stream;

public class JavaStreams {

public static void main(String[] args) throws IOException{

//0. Integer Stream

IntStream

.range(1,10).

forEach(System.out::print);

System.out.println("\n");

//1. Integer Stream with skip

System.out.println(

IntStream

.range(5,11) //add 5+6+7+8+9+10

.skip(4) //skip first 4 elements

.sum());

System.out.println("\n");

//2. Integer Stream with skip

IntStream

.range(1,10)

.skip(5) //skip first 5 elements

.forEach(x -> System.out.print(x));

System.out.println("\n");

//3. Integer Stream with sum

System.out.println(

IntStream

.range(1,10)

.sum());

System.out.println();

//4. Stream.of, sorted and then findFirst item

Stream.of("Ava","Aneri","Alberto")

.sorted()

.findFirst()

.ifPresent(System.out::println);

System.out.println();

//5. Stream from Array, sort, filter and print

String[] names = {"Al", "Ankit", "Kushal", "Brunt", "Sarika", "amanda", "Hans", "Shivika", "xyz", "shamili"};

Arrays.stream(names) //same as Stream.of(names)

.filter(x -> x.startsWith("S"))

.sorted()

.forEach(System.out::println);

System.out.println();

//6. average of squares of an int array

Arrays.stream(new int[] {2,4,6,8,10})

.map(x->x*x)

.average()

.ifPresent(System.out::println);

System.out.println();

//7. Stream from List, filter and print

List<String> people = Arrays.asList("Al", "Ankit", "Kushal", "Brunt", "Sarika", "amanda", "Hans", "Shivika", "xyz", "shamili");

people

.stream()

.map(String::toLowerCase)

.filter(x -> x.startsWith("a"))

.forEach(System.out::println);

System.out.println();

//8. streams rows from text file, sort, filter and print with more than 15 character

Stream<String> cricketer = Files.lines(Paths.get("cricketer.txt")); //kindly provide your own file location

//for example :- Stream<String> rows1 = Files.lines(Paths.get("C:\\Users\\Aaditya Raj\\eclipse-workspace\\CodePractice\\bin\\test\\cricketer.txt));

cricketer

.sorted()

.filter(x -> x.length() > 15)

.forEach(System.out::println);

cricketer.close();

System.out.println();

//9. streams rows from text file, sort, filter and print substring

List<String> cricketer2 = (List<String>) Files.lines(Paths.get("cricketer.txt")) //kindly provide your own file location

.filter(x -> x.contains("ja"))

.collect(Collectors.toList());

cricketer2.forEach(x -> System.out.println(x));

System.out.println();

//10. Stream rows from CSV file and filter out which rows don't have 3 item array and count all which have 3 items in it.

Stream<String> rows1 = Files.lines(Paths.get("data.txt")); //kindly provide your own file location

int rowCount = (int) rows1

.map(x -> x.split(","))

.filter(x -> x.length == 4)

.count();

System.out.println(rowCount + "rows.");

rows1.close();

System.out.println();

//11. Stream rows from CSV file, and parse data from rows

Stream<String> rows2 = Files.lines(Paths.get("data.txt")); //kindly provide your own file location

rows2

.map(x -> x.split(", "))

.filter(x -> x.length == 4)

.filter(x -> Integer.parseInt(x[1]) > 3)

.forEach(x -> System.out.println(x[0]+ " " +x[1]+ " " +x[2]));

rows2.close();

System.out.println();

//12. Stream rows from CSV file, store fields in HashMap as key-value pair

Stream<String> rows3 = Files.lines(Paths.get("data.txt")); //kindly provide your own file location

Map<String, Integer> map = new HashMap<>();

map = rows3

.map(x -> x.split(", "))

.filter(x -> x.length == 4)

.filter(x -> Integer.parseInt(x[1]) > 3)

.collect(Collectors.toMap(x->x[0], x-> Integer.parseInt(x[1])));

rows3.close();

for(String key : map.keySet()) {

System.out.println(key + " " + map.get(key));

}

System.out.println();

//13. Reduction - sum

double total = Stream.of(7.3, 1.5, 4.8)

.reduce(0.0, (Double a, Double b) -> a+b);

System.out.println("Total = "+total);

System.out.println();

//14. Reduction - summary statistics

IntSummaryStatistics summary = IntStream.of(7, 2, 19, 88, 73, 4, 10)

.summaryStatistics();

System.out.println(summary);

}

}