Goyummy

import java.util.List; public class FunctionalProgrammingMagic { public static long sumOfSquares(List numbers) { if(numbers == null){ return 0; } return numbers.stream() .mapToLong(n -> n * n) .sum(); } } mapToLong은 LongStream을 만들어주는 map의 특별한 버전이다.

import java.util.List; import java.util.stream.Collectors; public class FunctionalProgrammingMagic { public static List getCourseNameCharacterCount(List courses) { if(courses == null){ return List.of(); } return courses.stream() .map(s -> s.length()) .collect(Collectors.toList()); /* return courses.stream() .map(String::length) .collect(Collectors.toList()); */ } } 's -> s.length()' 은 'String::l..

import java.util.stream.Collectors; import java.util.stream.IntStream; import java.util.List; public class FunctionalProgrammingMagic { public static List getCubesOfFirstNNumbers(int n) { // Write your code here return IntStream.range(1,n+1) .map(e -> e * e * e) .boxed() .collect(Collectors.toList()); } } map을 이용하여 세제곱을 구한다. IntStream으로는 배열을 만드는 collect()를 사용할 수 없으므로 Stream으로 만들어주는 boxed()를 사용한다.

import java.util.Arrays; import java.util.Collections; import java.util.List; import java.util.stream.Collectors; public class FunctionalProgrammingMagic { public static List filterOddNumbers(List numbers) { List nums = numbers.stream() .filter(n -> n % 2 != 0) .collect(Collectors.toList()); return nums; } } 음수도 필터링하기 위해 'n % 2 != 0'을 사용했다.

// 1-10 제곱해서 출력 IntStream.range(1,11).map(e -> e * e).forEach(p->System.out.println(p)) //배열 안의 문자열 모두 소문자로 바꾸기 List.of("Apple","Ant","Bat").stream().map(s->s.toLowerCase()).forEach(p -> System.out.println(p)) // 배열 안의 문자열 길이 출력하기 List.of("Apple","Ant","Bat").stream().map(s->s.length()).forEach(p -> System.out.println(p))

public class StringMagic { public String reverseWordsInSentence(String sentence) { if(sentence == null){ return "INVALID"; }else if(sentence == ""){ return ""; } String[] words = sentence.split(" "); StringBuilder reversedSentence = new StringBuilder(); for(String word:words){ StringBuilder reversedStr = new StringBuilder(word).reverse(); reversedSentence.append(reversedStr).append(" "); } retur..

public class MyString { public String str; public MyString(String str) { this.str = str; } public boolean isHexadecimalChar(char ch) { return (ch>= 'a' && ch ='A' && ch

import java.util.Arrays; public class StringMagic { public boolean areAnagrams(String str1, String str2) { if(str1 == null || str2 == null){ return false; }else if(str1.length() != str2.length()){ return false; } str1 = str1.toLowerCase(); str2 = str2.toLowerCase(); char[] charArray1 = str1.toCharArray(); char[] charArray2 = str2.toCharArray(); Arrays.sort(charArray1); Arrays.sort(charArray2); r..

package com.collection; import java.util.HashMap; import java.util.Map; public class MapRunner { public static void main(String[] args){ String str = "This is an awesome occasion." + "This has never happend before."; Map occurances = new HashMap(); char[] characters = str.toCharArray(); //String을 char로 쪼개서 배열에 넣기 for(char character:characters) { Integer integer = occurances.get(character); //Map..

import java.util.ArrayList; import java.util.List; public class NumberMagic { public List determineMultiples(int number, int limit) { int multiple = number; ArrayList resultArray = new ArrayList(); if(number