Java 8 :Terminal operation sum, reduce, count, : map, array, Intermediate operations : filter,distinct,concat

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	package com.tvidushi.DONE;
	import java.util.ArrayList;
	import java.util.Arrays;
	import java.util.HashMap;
	import java.util.List;
	import java.util.Map;
	import java.util.regex.Pattern;
	import java.util.stream.Stream;
	public class _CommonOperation {
	public static List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
	/**
	* You are given a list of words & you have to count the number of elements
	* */
	public static void countElements(){
	System.out.print("Stream.of( __,__,__,).count() : "+Stream.of("abc","bca","bac","dca","efg").count());
	}
	/**
	* You are given a list of words & you have to count the number of elements of defined length
	* */
	public static void countElementsDefinedLength(){
	System.out.print("Stream.of( __,__,__,).filter().(Pattern.compile(---)).asPredicate()).count : ");
	System.out.print( Stream.of("abc","bca","bac","dca","efgUI")
	.filter(Pattern.compile("\\b\\w{3}\\b") //Predicate
	.asPredicate())
	.count());
	}
	/**
	* You are given a list of ethencity of people.
	* Find unique ethencities
	*/
	public static void countDistinctElements() {
	System.out.println("Count: ethicities listed list.stream().distinct().count()");
	List<String> list = Arrays.asList("white","white","hispanic",
	"asian","asian","african-american",
	"white","white","hispanic");
	System.out.println("Count: ethicities listed "+list.stream().distinct().count());
	}
	/**
	* You are given a list of ethencity of people.
	* Find unique ethencities
	*/
	public static void countElementInMultipleLists() {
	Stream<String> class_1 = Stream.of("Aradhya", "Abhinav", "Avinash","Supriya");
	Stream<String> class_2 = Stream.of("Anirudh", "Vinay", "Kiara","Abhinav","Supriya");
	System.out.println("Stream.concat(class_1, class_2)");
	Stream<String> commonNames = Stream.concat(class_1, class_2);
	commonNames.forEach(e->System.out.print(e+" "));
	}
	/**
	* You are given a list of ethencity of people.
	* Find unique ethencities
	*/
	public static void countDistinctElementInMultipleLists() {
	Stream<String> class_1 = Stream.of("Aradhya", "Abhinav", "Avinash","Supriya");
	Stream<String> class_2 = Stream.of("Anirudh", "Vinay", "Kiara","Abhinav","Supriya");
	System.out.println("Stream.concat(class_1, class_2).distinct()");
	Stream<String> commonNames = Stream.concat(class_1, class_2).distinct();
	commonNames.forEach(e->System.out.print(e+" "));
	}
	public static void sum_MapValues() {
	Map<String, Integer> num = new HashMap();
	num.put("1", 125);
	num.put("2", 125);
	System.out.println("num.values().stream().mapToInt(i -> i).sum())");
	System.out.println();
	System.out.println(" "+num.values().
	stream().
	mapToInt(i -> i).
	sum());
	}
	public static void sum_reduce() {
	System.out.println();
	System.out.println(
	numbers.stream()
	.reduce(0, (total, e) -> Integer.sum(total, e)));
	// .reduce(0, Integer::sum));
	}
	public static void sum_maptoint(String[] args) {
	//given the values, double the even numbers and total.
	System.out.println(
	numbers.stream()
	.filter(e -> e % 2 == 0)
	.mapToInt(e -> e * 2)
	.sum());
	}
	public static void example_3() {
	System.out.println("numbers.stream().reduce(0,(total,e)->Integer.sum(sum,e))");
	System.out.println(
	numbers.stream()
	.reduce(0, (total, e) -> Integer.sum(total, e)));
	}
	public static void concat_reduce() {
	System.out.println(
	numbers.stream()
	.map(String::valueOf)
	// .reduce("", (carry, str) -> carry.concat(str)));
	.reduce("", String::concat));
	}
	public static void sum_List() {
	List<Integer> list = new ArrayList<>(Arrays.asList(100,200,300));
	System.out.println("_________"+list.
	stream().
	mapToInt(i->i).sum());
	}
	public static void main(String[] args) {
	System.out.println();
	countElements();
	System.out.println();
	countElementsDefinedLength();
	System.out.println();
	countDistinctElements();
	System.out.println();
	countElementInMultipleLists() ;
	System.out.println();
	System.out.println();
	countDistinctElementInMultipleLists();
	System.out.println();
	concat_reduce();
	System.out.println();
	sum_List() ;
	}
	}

view raw _CommonOperation.java hosted with ❤ by GitHub

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