배열의 평균값
문제 설명
제한 사항
입출력 예
입출력 예 설명
문제 풀이
class Solution {
public double solution(int[] numbers) {
double avg = 0;
double sum = 0;
for (int i = 0; i < numbers.length; i++) {
sum += numbers[i];
}
avg = sum / numbers.length;
return avg;
}
}다른 사람의 풀이
class Solution {
public double solution(int[] numbers) {
return Arrays.stream(numbers).average().orElse(0);웹 페이지 디자인
2-13 style.css
textarea {
width:100%;
}
input[type=submit] {
margin-top:10px;
}2-13 style 적용
<link rel="stylesheet" type="text/css" th:href="@{/style.css}">2-14 부트스트랩 적용
<link rel="stylesheet" type="text/css" th:href="@{/bootstrap.min.css}">
<div class="container my-3">
<table class="table">
<thead class="table-dark">
<tr>
<th>번호</th>
<th>제목</th>
<th>작성일시</th>
</tr>
</thead>
<tbody>
<tr th:each="question, loop : ${questionList}">
<td th:text="${loop.count}"></td>
<td>
<a th:href="@{|/question/detail/${question.id}|}"
th:text="${question.subject}"></a>
</td>
<td th:text="${#temporals.format(question.createDate,
'yyyy-MM-dd HH:mm')}"></td>
</tr>
</tbody>
</table>
</div>2-14 question_detail 수정하기
<link rel="stylesheet" type="text/css" th:href="@{/bootstrap.min.css}">
<div class="container my-3">
<!-- 질문 -->
<h2 class="border-bottom py-2" th:text="${question.subject}"></h2>
<div class="card my-3">
<div class="card-body">
<div class="card-text" style="white-space: pre-line;" th:text="${question.content}"></div>
<div class="d-flex justify-content-end">
<div class="badge bg-light text-dark p-2 text-start">
<div th:text="${#temporals.format(question.createDate, 'yyyy-MM-dd HH:mm')}"></div>
</div>
</div>
</div>
</div>
<!-- 답변의 갯수 표시 -->
<h5 class="border-bottom my-3 py-2"
th:text="|${#lists.size(question.answerList)}개의 답변이 있습니다.|"></h5>
<!-- 답변 반복 시작 -->
<div class="card my-3" th:each="answer : ${question.answerList}">
<div class="card-body">
<div class="card-text" style="white-space: pre-line;" th:text="${answer.content}"></div>
<div class="d-flex justify-content-end">
<div class="badge bg-light text-dark p-2 text-start">
<div th:text="${#temporals.format(answer.createDate, 'yyyy-MM-dd HH:mm')}"></div>
</div>
</div>
</div>
</div>
<!-- 답변 반복 끝 -->
<!-- 답변 작성 -->
<form th:action="@{|/answer/create/${question.id}|}" method="post" class="my-3">
<textarea name="content" id="content" rows="10" class="form-control"></textarea>
<input type="submit" value="답변등록" class="btn btn-primary my-2">
</form>
</div>2-15 layout 기본 틀
<!doctype html>
<html lang="ko">
<head>
<!-- Required meta tags -->
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1,
shrink-to-fit=no">
<!-- Bootstrap CSS -->
<link rel="stylesheet" type="text/css" th:href="@{/bootstrap.min.css}">
<!-- sbb CSS -->
<link rel="stylesheet" type="text/css" th:href="@{/style.css}">
<title>Hello, sbb!</title>
</head>
<body>
<!-- 기본 템플릿 안에 삽입될 내용 Start -->
<th:block layout:fragment="content"></th:block>
<!-- 기본 템플릿 안에 삽입될 내용 End -->
</body>
</html>2-15 question_list.html, question_detail.html 템플릿 상속
<html layout:decorate="~{layout}">
<div layout:fragment="content" class="container my-3">
</html>2-16 question_list.html 질문 등록 버튼
</table>
<a th:href="@{/question/create}" class="btn btn-primary">질문 등록하기</a>
</div>닫히는 테이블 밑에 추가하기
2-16 create 매핑
@GetMapping("/create")
public String questionCreate() {
return "question_form";
}2-16 question_form
<html layout:decorate="~{layout}">
<div layout:fragment="content" class="container">
<h5 class="my-3 border-bottom pb-2">질문등록</h5>
<form th:action="@{/question/create}" method="post">
<div class="mb-3">
<label for="subject" class="form-label">제목</label>
<input type="text" name="subject" id="subject" class="form-control">
</div>
<div class="mb-3">
<label for="content" class="form-label">내용</label>
<textarea name="content" id="content" class="form-control" rows="10"></textarea>
</div>
<input type="submit" value="저장하기" class="btn btn-primary my-2">
</form>
</div>
</html>2-16 Controller
@PostMapping("/create")
public String questionCreate(@RequestParam(value = "subject") String subject,
@RequestParam(value = "content") String content) {
this.questionService.create(subject, content);
return "redirect:/question/list";
}Get 매핑 해줬으니 Post 만들기
2-16 Service
public void create(String subject, String content) {
Question q = new Question();
q.setSubject(subject);
q.setContent(content);
q.setCreateDate(LocalDateTime.now());
this.questionRepository.save(q);
}Post니까 데이터 저장해야 하니 서비스에 create 만들기
2-16 Validation
implementation 'org.springframework.boot:spring-boot-starter-validation'2-16 QuestionForm
@Getter
@Setter
public class QuestionForm {
@NotEmpty(message = "제목은 필수항목입니다.")
@Size(max = 200)
private String subject;
@NotEmpty(message = "내용은 필수항목입니다.")
private String content;
}폼 써야하니까 폼 클래스 작성
2-16 Controller에 Form 추가
@PostMapping("/create")
public String questionCreate(@Valid QuestionForm questionForm,
BindingResult bindingResult) {
if (bindingResult.hasErrors()) {
return "question_form";
}
this.questionService.create(questionForm.getSubject(),
questionForm.getContent());
return "redirect:/question/list";
}2-16 question_form 템플릿 수정
<html layout:decorate="~{layout}">
<div layout:fragment="content" class="container">
<h5 class="my-3 border-bottom pb-2">질문등록</h5>
<form th:action="@{/question/create}" th:object="${questionForm}" method="post">
<div class="alert alert-danger" role="alert" th:if="${#fields.hasAnyErrors()}">
<div th:each="err : ${#fields.allErrors()}" th:text="${err}" />
</div>
<div class="mb-3">
<label for="subject" class="form-label">제목</label>
<input type="text" name="subject" id="subject" class="form-control">
</div>
<div class="mb-3">
<label for="content" class="form-label">내용</label>
<textarea name="content" id="content" class="form-control" rows="10"></textarea>
</div>
<input type="submit" value="저장하기" class="btn btn-primary my-2">
</form>
</div>
</html>form 안에 create, post 사이에 th:object 추가
그 밑에 div 추가
2-16 Controller th:object 한테 필요한 Form 추가하기
@GetMapping("/create")
public String questionCreate(QuestionForm questionForm) {
return "question_form";
}2-16 question_form 2차 수정
<html layout:decorate="~{layout}">
<div layout:fragment="content" class="container">
<h5 class="my-3 border-bottom pb-2">질문등록</h5>
<form th:action="@{/question/create}" th:object="${questionForm}" method="post">
<div class="alert alert-danger" role="alert" th:if="${#fields.hasAnyErrors()}">
<div th:each="err : ${#fields.allErrors()}" th:text="${err}" />
</div>
<div class="mb-3">
<label for="subject" class="form-label">제목</label>
<input type="text" th:field="*{subject}" class="form-control">
</div>
<div class="mb-3">
<label for="content" class="form-label">내용</label>
<textarea th:field="*{content}" class="form-control" rows="10"></textarea>
</div>
<input type="submit" value="저장하기" class="btn btn-primary my-2">
</form>
</div>
</html>name, subject 그리고 name, content 지우고 th:field 사용
2-16 AnswerForm
@Getter
@Setter
public class AnswerForm {
@NotEmpty(message = "내용은 필수항목입니다.")
private String content;
}2-16 AnswerController
@PostMapping("/create/{id}")
public String createAnswer(Model model, @PathVariable("id") Integer id,
@Valid AnswerForm answerForm,
BindingResult bindingResult) {
Question question = this.questionService.getQuestion(id);
if (bindingResult.hasErrors()) {
model.addAttribute("question", question);
return "question_detail";
}
this.answerService.create(question, answerForm.getContent());
return String.format("redirect:/question/detail/%s", id);
}@Valid, BindResult 검증 진행
2-16 question_detail
<html layout:decorate="~{layout}">
<div layout:fragment="content" class="container my-3">
<!-- 질문 -->
<h2 class="border-bottom py-2" th:text="${question.subject}"></h2>
<div class="card my-3">
<div class="card-body">
<div class="card-text" style="white-space: pre-line;" th:text="${question.content}"></div>
<div class="d-flex justify-content-end">
<div class="badge bg-light text-dark p-2 text-start">
<div th:text="${#temporals.format(question.createDate, 'yyyy-MM-dd HH:mm')}"></div>
</div>
</div>
</div>
</div>
<!-- 답변의 갯수 표시 -->
<h5 class="border-bottom my-3 py-2"
th:text="|${#lists.size(question.answerList)}개의 답변이 있습니다.|"></h5>
<!-- 답변 반복 시작 -->
<div class="card my-3" th:each="answer : ${question.answerList}">
<div class="card-body">
<div class="card-text" style="white-space: pre-line;" th:text="${answer.content}"></div>
<div class="d-flex justify-content-end">
<div class="badge bg-light text-dark p-2 text-start">
<div th:text="${#temporals.format(answer.createDate, 'yyyy-MM-dd HH:mm')}"></div>
</div>
</div>
</div>
</div>
<!-- 답변 반복 끝 -->
<!-- 답변 작성 -->
<form th:action="@{|/answer/create/${question.id}|}" th:object="${answerForm}" method="post" class="my-3">
<div th:replace="~{form_errors :: formErrorsFragment}"></div>
<textarea th:field="*{content}" rows="10" class="form-control"></textarea>
<input type="submit" value="답변등록" class="btn btn-primary my-2">
</form>
</div>
</html>2-16 QuestioController
@GetMapping(value = "/detail/{id}")
public String detail(Model model, @PathVariable("id") Integer id,
AnswerForm answerForm) {
Question question = this.questionService.getQuestion(id);
model.addAttribute("question", question);
return "question_detail";
}AnswerForm 추가
2-16 Form Error
<div th:fragment="formErrorsFragment" class="alert alert-danger"
role="alert" th:if="${#fields.hasAnyErrors()}">
<div th:each="err : ${#fields.allErrors()}" th:text="${err}" />
</div>2-16 기존 템플릿에 form error 추가
<html layout:decorate="~{layout}">
<div layout:fragment="content" class="container">
<h5 class="my-3 border-bottom pb-2">질문등록</h5>
<form th:action="@{/question/create}" th:object="${questionForm}" method="post">
<div th:replace="~{form_errors :: formErrorsFragment}"></div>
<div class="mb-3">
<label for="subject" class="form-label">제목</label>
<input type="text" th:field="*{subject}" class="form-control">
</div>
<div class="mb-3">
<label for="content" class="form-label">내용</label>
<textarea th:field="*{content}" class="form-control" rows="10"></textarea>
</div>
<input type="submit" value="저장하기" class="btn btn-primary my-2">
</form>
</div>
</html>
코딩하는 곤쪽이