Initialized.

.gitignore

@@ -0,0 +1,29 @@
+### IntelliJ IDEA ###
+out/
+!**/src/main/**/out/
+!**/src/test/**/out/
+
+### Eclipse ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+bin/
+!**/src/main/**/bin/
+!**/src/test/**/bin/
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+
+### VS Code ###
+.vscode/
+
+### Mac OS ###
+.DS_Store

java-algorithm-interview.iml

@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+      <sourceFolder url="file://$MODULE_DIR$/test" isTestSource="true" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+    <orderEntry type="module-library" scope="TEST">
+      <library name="JUnit5.8.1">
+        <CLASSES>
+          <root url="jar://$MAVEN_REPOSITORY$/org/junit/jupiter/junit-jupiter/5.8.1/junit-jupiter-5.8.1.jar!/" />
+          <root url="jar://$MAVEN_REPOSITORY$/org/junit/jupiter/junit-jupiter-api/5.8.1/junit-jupiter-api-5.8.1.jar!/" />
+          <root url="jar://$MAVEN_REPOSITORY$/org/opentest4j/opentest4j/1.2.0/opentest4j-1.2.0.jar!/" />
+          <root url="jar://$MAVEN_REPOSITORY$/org/junit/platform/junit-platform-commons/1.8.1/junit-platform-commons-1.8.1.jar!/" />
+          <root url="jar://$MAVEN_REPOSITORY$/org/apiguardian/apiguardian-api/1.1.2/apiguardian-api-1.1.2.jar!/" />
+          <root url="jar://$MAVEN_REPOSITORY$/org/junit/jupiter/junit-jupiter-params/5.8.1/junit-jupiter-params-5.8.1.jar!/" />
+          <root url="jar://$MAVEN_REPOSITORY$/org/junit/jupiter/junit-jupiter-engine/5.8.1/junit-jupiter-engine-5.8.1.jar!/" />
+          <root url="jar://$MAVEN_REPOSITORY$/org/junit/platform/junit-platform-engine/1.8.1/junit-platform-engine-1.8.1.jar!/" />
+        </CLASSES>
+        <JAVADOC />
+        <SOURCES />
+      </library>
+    </orderEntry>
+    <orderEntry type="library" name="KotlinJavaRuntime" level="project" />
+  </component>
+</module>

src/ch02/GenericExample.java

@@ -0,0 +1,31 @@
+package ch02;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class GenericExample {
+    public static void main(String[] args) {
+        List listNames1 = new ArrayList();
+        listNames1.add("카리나");
+        listNames1.add("윈터");
+        listNames1.add("지젤");
+        listNames1.add("닝닝");
+        String name0 = (String) listNames1.get(0);
+
+        listNames1.add(34);
+        // String name4 = (String) listNames1.get(4); // 에러 발생
+
+        // ---
+
+        List<String> listNames2 = new ArrayList<String>();
+        listNames2.add("카리나");
+        listNames2.add("윈터");
+        listNames2.add("지젤");
+        listNames2.add("닝닝");
+        // listNames2.add(34); // 에러 발생
+
+        for (String name : listNames2) {
+            System.out.println(name);
+        }
+    }
+}

src/ch02/LambdaExpressionExample.java

@@ -0,0 +1,23 @@
+package ch02;
+
+public class LambdaExpressionExample {
+    @FunctionalInterface
+    interface MathInterface {
+        double getPiValue();
+    }
+
+    public static void main(String[] args) {
+        MathInterface math1 = new MathInterface() {
+            @Override
+            public double getPiValue() {
+                return 3.141592;
+            }
+        };
+        System.out.println("Pi: " + math1.getPiValue());
+
+        // ---
+
+        MathInterface math2 = () -> 3.141592;
+        System.out.println("Pi: " + math2.getPiValue());
+    }
+}

src/ch02/LambdaExpressionSortExample.java

@@ -0,0 +1,56 @@
+package ch02;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.List;
+
+public class LambdaExpressionSortExample {
+    static class Member {
+        String name;
+        int age;
+
+        public Member(String name, int age) {
+            this.name = name;
+            this.age = age;
+        }
+
+        @Override
+        public String toString() {
+            return "Member{" +
+                    "name='" + name + '\'' +
+                    ", age=" + age +
+                    '}';
+        }
+    }
+
+    public static void main(String[] args) {
+        // 리스트에 데이터 삽입
+        List<Member> members1 = new ArrayList<>();
+        members1.add(new Member("윈터", 23));
+        members1.add(new Member("카리나", 24));
+        members1.add(new Member("닝닝", 22));
+
+        // 정렬을 익명 클래스로 구현
+        Collections.sort(members1, new Comparator<Member>() {
+            @Override
+            public int compare(Member o1, Member o2) {
+                return o2.age - o1.age;
+            }
+        });
+
+        System.out.println(members1);
+
+        // ---
+
+        List<Member> members2 = new ArrayList<>();
+        members2.add(new Member("윈터", 23));
+        members2.add(new Member("카리나", 24));
+        members2.add(new Member("닝닝", 22));
+
+        // 정렬을 람다 표현식으로 구현
+        members2.sort((o1, o2) -> o2.age - o1.age);
+
+        System.out.println(members2);
+    }
+}

src/ch02/SteamAPIExample.java

@@ -0,0 +1,74 @@
+package ch02;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.stream.Collectors;
+
+public class SteamAPIExample {
+    static class Member {
+        String name;
+        int age;
+
+        public Member(String name, int age) {
+            this.name = name;
+            this.age = age;
+        }
+    }
+
+    public static void main(String[] args) {
+        List<Member> members1 = new ArrayList<>();
+        members1.add(new Member("카리나", 24));
+        members1.add(new Member("윈터", 23));
+        members1.add(new Member("지젤", 24));
+        members1.add(new Member("닝닝", 22));
+
+        // 스트림 API를 사용하지 않은 예전 방식
+        List<String> chosenMembers = new ArrayList<>();
+        // 나이가 24세인 멤버의 이름을 chosenMembers 리스트에 삽입
+        for (Member member : members1) {
+            if (member.age == 24)
+                chosenMembers.add(member.name);
+        }
+        // chosenMembers 정렬
+        Collections.sort(chosenMembers);
+        // chosenMembers 출력
+        for (String name : chosenMembers) {
+            System.out.println(name);
+        }
+
+        // ---
+
+        List<Member> members2 = new ArrayList<>();
+        members2.add(new Member("카리나", 24));
+        members2.add(new Member("윈터", 23));
+        members2.add(new Member("지젤", 24));
+        members2.add(new Member("닝닝", 22));
+
+        members2.stream()                       // 스트림 API
+                .filter(m -> m.age == 24)       // 24세 필터링
+                .map(m -> m.name)               // 이름 매핑
+                .sorted()                       // 정렬
+                .collect(Collectors.toList())   // 리스트로 취합(아래 출력시 생략 가능)
+                .forEach(System.out::println);  // 메소드 참조로 출력
+
+        // ---
+
+        // 숫자 리스트
+        List<Double> numbers1 = Arrays.asList(49.1, 25.5, 9.9);
+        // 람다 표현식
+        numbers1.stream()                               // 스트림 API
+                .map(n -> Math.round(n))                // 반올림 처리
+                .forEach(n -> System.out.println(n));   // 순회하며 출력
+
+        // ---
+
+        // 숫자 리스트
+        List<Double> numbers2 = Arrays.asList(49.1, 25.5, 9.9);
+        // 메소드 참조
+        numbers2.stream()                       // 스트림 API
+                .map(Math::round)               // 반올림 처리
+                .forEach(System.out::println);  // 순회하며 출력
+    }
+}

src/ch03/Array.kt

@@ -0,0 +1,6 @@
+package ch03
+
+fun main() {
+    val arr: Array<Int> = arrayOf(5, 1, 3)
+    println(arr.max())
+}

src/ch03/JavaConditionExample.java

@@ -0,0 +1,27 @@
+package ch03;
+
+public class JavaConditionExample {
+    public String getTypeOfDayWithSwitchStatement(int dayOfWeek) {
+        String typeOfDay;
+        switch (dayOfWeek) {
+            case 1:
+                typeOfDay = "한 주의 시작";
+                break;
+            case 2:
+            case 3:
+            case 4:
+                typeOfDay = "주중";
+                break;
+            case 5:
+                typeOfDay = "한 주의 끝";
+                break;
+            case 6:
+            case 7:
+                typeOfDay = "주말";
+                break;
+            default:
+                throw new IllegalArgumentException("잘못된 날: " + dayOfWeek);
+        }
+        return typeOfDay;
+    }
+}

src/ch03/KotlinConditionExample.kt

@@ -0,0 +1,12 @@
+package ch03
+
+fun getTypeOfDayWithSwitchStatement(dayOfWeek: Int): String {
+    val typeOfDay: String = when (dayOfWeek) {
+        1 -> "한 주의 시작"
+        2, 3, 4 -> "주중"
+        5 -> "한 주의 끝"
+        6, 7 -> "주말"
+        else -> throw IllegalArgumentException("잘못된 날: $dayOfWeek")
+    }
+    return typeOfDay
+}