diff --git a/firstClass/basicAssignments/.gitignore b/firstClass/basicAssignments/.gitignore
new file mode 100644
index 0000000..f68d109
--- /dev/null
+++ b/firstClass/basicAssignments/.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
\ No newline at end of file
diff --git a/firstClass/basicAssignments/.idea/misc.xml b/firstClass/basicAssignments/.idea/misc.xml
new file mode 100644
index 0000000..e0844bc
--- /dev/null
+++ b/firstClass/basicAssignments/.idea/misc.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_11" default="true" project-jdk-name="11" project-jdk-type="JavaSDK">
+    <output url="file://$PROJECT_DIR$/out" />
+  </component>
+</project>
\ No newline at end of file
diff --git a/firstClass/basicAssignments/.idea/modules.xml b/firstClass/basicAssignments/.idea/modules.xml
new file mode 100644
index 0000000..0a5f05a
--- /dev/null
+++ b/firstClass/basicAssignments/.idea/modules.xml
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectModuleManager">
+    <modules>
+      <module fileurl="file://$PROJECT_DIR$/basicAssignments.iml" filepath="$PROJECT_DIR$/basicAssignments.iml" />
+    </modules>
+  </component>
+</project>
\ No newline at end of file
diff --git a/firstClass/basicAssignments/.idea/workspace.xml b/firstClass/basicAssignments/.idea/workspace.xml
new file mode 100644
index 0000000..b35d216
--- /dev/null
+++ b/firstClass/basicAssignments/.idea/workspace.xml
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectId" id="2OQCXsl4f0NEz75qY8fDqsAgjMS" />
+</project>
\ No newline at end of file
diff --git a/firstClass/basicAssignments/basicAssignments.iml b/firstClass/basicAssignments/basicAssignments.iml
new file mode 100644
index 0000000..c90834f
--- /dev/null
+++ b/firstClass/basicAssignments/basicAssignments.iml
@@ -0,0 +1,11 @@
+<?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" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>
\ No newline at end of file
diff --git a/firstClass/basicAssignments/src/Main.java b/firstClass/basicAssignments/src/Main.java
new file mode 100644
index 0000000..3e59c38
--- /dev/null
+++ b/firstClass/basicAssignments/src/Main.java
@@ -0,0 +1,5 @@
+public class Main {
+    public static void main(String[] args) {
+        System.out.println("Hello world!");
+    }
+}
\ No newline at end of file
diff --git a/firstClass/basicAssignments/src/abstractMethod.java b/firstClass/basicAssignments/src/abstractMethod.java
new file mode 100644
index 0000000..20ef37c
--- /dev/null
+++ b/firstClass/basicAssignments/src/abstractMethod.java
@@ -0,0 +1,34 @@
+abstract class Food{ // 부모 클래스 추상화
+
+    abstract public void eat(String name); // 선언은 되어 있으나 구현은 하지 않은 상태
+    abstract public void hate(String food);
+
+    abstract public void count(int food);
+
+    }
+class Eggplant extends Food {		// 추상클래스 Food를 상속받은 자손 클래스
+    @Override
+    public void eat(String name) {			// 오버라이드
+        System.out.println(name + "이 음식을 먹습니다.");
+    }
+    @Override
+    public void hate(String food){
+        System.out.println("으! 아차! 이 음식은" + food + "였네요." );
+    }
+    @Override
+
+    public void count(int food){
+        System.out.println("맛있는건줄 알고 " + food + "개나 먹었어요.");
+    }
+}
+
+
+public class abstractMethod {
+    public static void main(String[] args) {
+        Eggplant eggplant = new Eggplant(); // 인스턴스
+        eggplant.eat("유진");
+        eggplant.hate("가지");
+        eggplant.count(3); // 오버 로딩 같은 food 지만 다른 타입으로 동작
+    }
+}
+
diff --git a/firstClass/basicAssignments/src/generic.java b/firstClass/basicAssignments/src/generic.java
new file mode 100644
index 0000000..05716a6
--- /dev/null
+++ b/firstClass/basicAssignments/src/generic.java
@@ -0,0 +1,29 @@
+class Test<T>{ // 제네릭 클래스 생성
+    private T value;
+
+    public T get() {
+        return value;
+    }
+    public void set(T value) {
+        this.value = value;
+    }
+
+}
+
+public class generic {
+
+    public static void main(String[] args) {
+        Test<String> StringGeneric = new Test<String>(); // 제네릭 인스턴스 타입을 다르게 생성
+        Test<Integer> IntGeneric = new Test<Integer>();
+
+        StringGeneric.set("어려운것 같아요");
+        String str = StringGeneric.get(); // String 형식
+
+        IntGeneric.set(20);
+        int val = IntGeneric.get(); // Int 형식
+
+        System.out.println("제네릭은 " + str);
+        System.out.println("한 이정도..." + val);
+    }
+
+}
\ No newline at end of file
diff --git a/firstClass/basicAssignments/src/interfaceJava.java b/firstClass/basicAssignments/src/interfaceJava.java
new file mode 100644
index 0000000..0f77ed6
--- /dev/null
+++ b/firstClass/basicAssignments/src/interfaceJava.java
@@ -0,0 +1,34 @@
+interface Animal {                  // Animal 인터페이스
+    public abstract void talk();
+
+}
+
+interface Feed {                    // Food 인터페이스
+    public abstract void food(String food);
+    public abstract void cnt(int cnt);
+}
+
+class Hamster implements Animal,Feed { // 인터페이스 다중 상속 가능
+    public String talk = "쥑쥑";
+
+    @Override                           // 인터페이스의 경우 모든 메서드를 무조건 호출
+    public void talk() {
+        System.out.println("햄스터는 " + this.talk);
+    }
+    @Override
+    public void food(String food) {
+        System.out.println("나는 " + food + "를 좋아해");
+    }
+    @Override
+    public void cnt(int cnt) {
+        System.out.println("오늘 " + cnt + "개 먹었어.쥑쥑");
+    }
+}
+public class interfaceJava {
+    public static void main(String[] args) {
+        Hamster hamster = new Hamster();
+        hamster.talk();
+        hamster.food("해바라기씨");
+        hamster.cnt(5);
+    }
+}
diff --git a/firstClass/moreAssignment/.gitignore b/firstClass/moreAssignment/.gitignore
new file mode 100644
index 0000000..f68d109
--- /dev/null
+++ b/firstClass/moreAssignment/.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
\ No newline at end of file
diff --git a/firstClass/moreAssignment/.idea/.gitignore b/firstClass/moreAssignment/.idea/.gitignore
new file mode 100644
index 0000000..13566b8
--- /dev/null
+++ b/firstClass/moreAssignment/.idea/.gitignore
@@ -0,0 +1,8 @@
+# Default ignored files
+/shelf/
+/workspace.xml
+# Editor-based HTTP Client requests
+/httpRequests/
+# Datasource local storage ignored files
+/dataSources/
+/dataSources.local.xml
diff --git a/firstClass/moreAssignment/.idea/jpa-buddy.xml b/firstClass/moreAssignment/.idea/jpa-buddy.xml
new file mode 100644
index 0000000..966d5f5
--- /dev/null
+++ b/firstClass/moreAssignment/.idea/jpa-buddy.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="JpaBuddyIdeaProjectConfig">
+    <option name="renamerInitialized" value="true" />
+  </component>
+</project>
\ No newline at end of file
diff --git a/firstClass/moreAssignment/.idea/misc.xml b/firstClass/moreAssignment/.idea/misc.xml
new file mode 100644
index 0000000..3950286
--- /dev/null
+++ b/firstClass/moreAssignment/.idea/misc.xml
@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_11" default="true" project-jdk-name="11" project-jdk-type="JavaSDK">
+    <output url="file://$PROJECT_DIR$/out" />
+  </component>
+  <component name="ProjectType">
+    <option name="id" value="jpab" />
+  </component>
+</project>
\ No newline at end of file
diff --git a/firstClass/moreAssignment/.idea/modules.xml b/firstClass/moreAssignment/.idea/modules.xml
new file mode 100644
index 0000000..b02988b
--- /dev/null
+++ b/firstClass/moreAssignment/.idea/modules.xml
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectModuleManager">
+    <modules>
+      <module fileurl="file://$PROJECT_DIR$/moreAssignment.iml" filepath="$PROJECT_DIR$/moreAssignment.iml" />
+    </modules>
+  </component>
+</project>
\ No newline at end of file
diff --git a/firstClass/moreAssignment/.idea/vcs.xml b/firstClass/moreAssignment/.idea/vcs.xml
new file mode 100644
index 0000000..b2bdec2
--- /dev/null
+++ b/firstClass/moreAssignment/.idea/vcs.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$/../.." vcs="Git" />
+  </component>
+</project>
\ No newline at end of file
diff --git a/firstClass/moreAssignment/moreAssignment.iml b/firstClass/moreAssignment/moreAssignment.iml
new file mode 100644
index 0000000..c90834f
--- /dev/null
+++ b/firstClass/moreAssignment/moreAssignment.iml
@@ -0,0 +1,11 @@
+<?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" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>
\ No newline at end of file
diff --git a/firstClass/moreAssignment/src/Bank.java b/firstClass/moreAssignment/src/Bank.java
new file mode 100644
index 0000000..2226d93
--- /dev/null
+++ b/firstClass/moreAssignment/src/Bank.java
@@ -0,0 +1,151 @@
+import java.util.Scanner;
+import java.util.Random;
+
+public class Bank {
+    private static Service[] accounts = new Service[20]; // 리스트 생성
+    private static int index = 0;
+
+    public static int checkAccountNumber(String accountNumber) {
+        for(int i=0; i<index; i++){
+            if(accounts[i].getAccountNumber().contentEquals(accountNumber)){        // 받은 계좌와, getAccountNumber()에서 가져온 계좌가 일치하는지 확인.
+                return i;
+            }
+        } return -1;
+    }
+
+    public static void getAccountList(){                                                // 계좌 리스트를 불러옴.
+        for(int i=0; i< index; i++) {
+            System.out.printf("%s%n", accounts[i].getAccountInfo());                    // for문으로 전체 리스트 호출
+        }
+    }
+
+    public static void createAccount() {                                                // 계좌를 생성하는 메서드
+        Random random = new Random();
+        Scanner scanner = new Scanner((System.in));
+        String accountNumber = (random.nextInt(90000) + 10000 ) + "-" + (random.nextInt(90000) + 10000 );   // 무작위 계좌
+        System.out.println("계좌번호: " + accountNumber);                                 // 계좌는 임의로 생성 후 바로 사용자에게 보여줌.
+        System.out.print("고객이름: ");                                                 // 나머지는 scanner을 통해 입력 받은 값 사용.
+        String name = scanner.nextLine();
+        System.out.print("비밀번호: ");
+        String password = scanner.nextLine();
+        int budget = 0;                                                                 // 입금이 되어있는 상태가 아니기 때문에 0으로 시작.
+        System.out.print("금액: "+budget);
+
+        accounts[index] = new Service(accountNumber, password, name, budget);
+        index ++;                                                                       // 새로운 계좌가 생길때마다 index++
+
+        System.out.println(accountNumber + "인 계좌 계설 완료!");
+
+    }
+
+    public static void findAccount() {
+        Scanner sc = new Scanner(System.in);
+        System.out.print("계좌번호를 입력해주세요.");
+        String accountNumber = sc.nextLine() ;
+
+        int index = checkAccountNumber(accountNumber);                                  // 함수를 통해 위에서 받은 accountNumber가 일치하는지 확인.
+        if (index == -1) {
+            System.out.println("계좌가 존재하지 않습니다.");
+        } else {
+            System.out.printf("계좌번호 %d%n", accounts[index].getBudget());
+        }
+
+
+    }
+
+    public static void moneyIn() {
+        Scanner scanner = new Scanner((System.in));
+
+        System.out.print(("계좌번호를 입력해주세요.: "));
+        String accountNumber = scanner.nextLine();
+        System.out.print("입금할 금액: ");
+        int money = scanner.nextInt();
+        int index = checkAccountNumber(accountNumber);                                      // 위 와 일치.
+        if (index == -1) {
+            System.out.println("계좌가 존재하지 않습니다.");
+        } else {
+            accounts[index].deposit(money);
+        }
+
+    }
+
+    public static void moneyOut() {
+        Scanner scanner = new Scanner((System.in));
+        System.out.print("계좌번호를 입력해주세요.");
+        String accountNumber = scanner.nextLine();
+        System.out.print("비밀번호 확인이 필요합니다.: ");
+        String password = scanner.nextLine();
+        int index = checkAccountNumber(accountNumber);
+        if (index == -1) {
+            System.out.println("계좌가 존재하지 않습니다.");
+        } else {
+            if (!accounts[index].getPassword().equals(password)) {                  // 계좌가 존재하기는 하나 출금을 위해 비밀번호 확인
+                System.out.println("비밀번호가 일치하지 않습니다.");
+
+            } else {
+                accounts[index].withdraw();
+            }
+        }
+
+    }
+
+    public static void changePassword(){
+        Scanner scanner = new Scanner((System.in));
+        System.out.print("계좌번호를 입력해주세요.");
+        String accountNumber = scanner.nextLine();
+        int index = checkAccountNumber(accountNumber);
+        if (index == -1) {
+            System.out.println("계좌가 존재하지 않습니다.");
+        } else {
+            System.out.print("이전 비밀번호를 입력해주세요.: ");                           // 일치할시만 통과
+            String password = scanner.nextLine();
+            if (!accounts[index].getPassword().equals(password)) {
+                System.out.println("비밀번호가 일치하지 않습니다.");
+            } else {
+                System.out.print("바꾸고 싶은 비밀번호를 입력해주세요.: ");
+                String afterPassword = scanner.nextLine();
+                accounts[index].setPassword(afterPassword);                             // 새로 받은 비밀번호를 this.password = password를 통해 재정의
+                System.out.println("비밀번호를 변경 했습니다.");
+            }
+        }
+    }
+
+    public static void main(String[] args) {
+        Scanner scan = new Scanner(System.in);
+        while (true){
+            System.out.println("1. 계좌 개설 2. 입금  3. 출금 4. 잔액 조회 5. 전체 계좌 조회 6. 비밀번호 변경");
+            System.out.println("원하는 메뉴를 선택해주세요.");
+
+            int num = scan.nextInt();
+            switch (num) {                                                              // 받은 번호의 case를 실행.
+                case 1 :
+                    System.out.println("계좌를 개설합니다.");
+                    createAccount();
+                    break;
+                case 2 :
+                    System.out.println("입금입니다.");
+                    moneyIn();
+                    break;
+                case 3 :
+                    System.out.println("출금 입니다.");
+                    moneyOut();
+                    break;
+                case 4:
+                    System.out.println("현재 잔액을 조회합니다.");
+                    findAccount();
+                    break;
+                case 5:
+                    System.out.println("전체 계좌 조회");
+                    getAccountList();
+                    break;
+                case 6:
+                    System.out.println(" 비밀번호를 바꿉니다.");
+                    changePassword();
+                    break;
+                default:
+                    System.out.println("정해진 숫자 값이 아닙니다.");
+
+            }
+        }
+    }
+}
diff --git a/firstClass/moreAssignment/src/Service.java b/firstClass/moreAssignment/src/Service.java
new file mode 100644
index 0000000..58c666a
--- /dev/null
+++ b/firstClass/moreAssignment/src/Service.java
@@ -0,0 +1,66 @@
+import java.util.Scanner;
+class Service{
+    private String accountNumber;
+    private String password;
+    private String name;
+    private int budget;
+
+    public Service(String accountNumber, String password, String name, int budget){   // Service 리스트 만들기 위한 요소
+        this.accountNumber = accountNumber;
+        this.password = password;
+        this.name = name;
+        this.budget = budget;
+    }
+    public void setBudget(int budget){this.budget = budget;}
+    public int getBudget(){ // 잔액
+        return budget;
+    }
+
+    public void setPassword(String password) { // 비밀번호 설정 현재 비밀번호를, 받은 비밀번호로 변경
+        this.password = password;
+    }
+
+    public String getPassword(){
+        return password;
+    }
+
+    public void deposit(int money) {
+        if (money <= 0) {                                   // 받은 금액이 0 이하 일 경우 입금 불가
+            System.out.println("금액이 0이거나 0보다 작습니다.");
+            return;
+        }
+        setBudget(budget+money);
+        System.out.println(money + "원을 출금했습니다. 현재 잔고는 "+ budget+"원 입니다.");
+    }
+
+    public void withdraw() {
+        Scanner sc = new Scanner(System.in);
+
+        while (true){
+            System.out.print("출금할 금액: ");
+            int money = sc.nextInt();
+
+            if (money > budget) {                                // 출금 금액이 현재 잔액보다 클 경우 출금 불가
+                System.out.println("출금 금액이 잔고보다 큽니다. 현재 잔고는 " + budget + "원 입니다.");
+                break;
+            }
+            else if (money <= 0) {
+                System.out.println("0 이하의 금액은 출금할 수 없습니다. 현재 잔고는 \" + budget + \"원 입니다.");
+                break;
+            } else {
+                setBudget(budget - money);
+                System.out.println(money + "원을 출금했습니다. 현재 잔고는 " + budget + "원 입니다.");
+                break;
+            }
+        }
+    }
+    public String getAccountNumber() {                      // 계좌 정보를 불러옴
+        return accountNumber;
+    }
+
+    public String getAccountInfo(){                        // 현재 있는 정보를 모두 불러옴.
+        return "계좌번호: " + accountNumber + ", 고객이름: " + name + ", 비밀번호: " + password + ", 잔액: " + budget;
+    }
+
+
+}
\ No newline at end of file