diff --git a/Practice01/AuthMethod.java b/Practice01/AuthMethod.java
new file mode 100644
index 0000000..035616e
--- /dev/null
+++ b/Practice01/AuthMethod.java
@@ -0,0 +1,5 @@
+package Practice01;
+
+public class AuthMethod {
+ public enum authMethod{Fingerprint, Pattern, Pin, Face};
+}
diff --git a/Practice01/Company.java b/Practice01/Company.java
new file mode 100644
index 0000000..f12d9f9
--- /dev/null
+++ b/Practice01/Company.java
@@ -0,0 +1,5 @@
+package Practice01;
+
+public class Company {
+ public enum companyName {SAMSUNG, LG, APPLE}
+}
diff --git a/Practice01/Electronic.java b/Practice01/Electronic.java
new file mode 100644
index 0000000..adfbd7e
--- /dev/null
+++ b/Practice01/Electronic.java
@@ -0,0 +1,78 @@
+package Practice01;
+
+import java.util.Arrays;
+import java.util.Objects;
+
+public class Electronic {
+ private String productNo;
+ private String modelName;
+ private String dateOfMade;
+
+ private Company companyName;
+ private AuthMethod[] arrAuth;
+
+
+ @Override
+ public String toString() {
+ return "Electronic{" +
+ "productNo='" + productNo + '\'' +
+ ", modelName='" + modelName + '\'' +
+ ", dateOfMade='" + dateOfMade + '\'' +
+ '}';
+ }
+
+ public String getProductNo() {
+ return productNo;
+ }
+
+ public void setProductNo(String productNo) {
+ this.productNo = productNo;
+ }
+
+ public String getModelName() {
+ return modelName;
+ }
+
+ public void setModelName(String modelName) {
+ this.modelName = modelName;
+ }
+ public Company getCompanyName() {
+ return companyName;
+ }
+
+ public void setCompanyName(Company companyName) {
+ this.companyName = companyName;
+ }
+ public String getDateOfMade() {
+ return dateOfMade;
+ }
+
+ public void setDateOfMade(String dateOfMade) {
+ this.dateOfMade = dateOfMade;
+ }
+
+ public AuthMethod[] getArrAuth() {
+ return arrAuth;
+ }
+
+ public void setArrAuth(AuthMethod[] arrAuth) {
+ this.arrAuth = arrAuth;
+ }
+
+ @Override
+ public boolean equals(Object o) {
+ if (this == o) return true;
+ if (o == null || getClass() != o.getClass()) return false;
+ Electronic e = (Electronic) o;
+ return Objects.equals(productNo, e.productNo) &&
+ Objects.equals(modelName, e.modelName) &&
+ Objects.equals(dateOfMade, e.dateOfMade);
+ }
+
+ @Override
+ public int hashCode() {
+ int result=Objects.hash(productNo, modelName, dateOfMade);
+ result=31*result+ Arrays.hashCode(arrAuth);
+ return result;
+ }
+}
diff --git a/Practice01/User.java b/Practice01/User.java
new file mode 100644
index 0000000..a0ac22a
--- /dev/null
+++ b/Practice01/User.java
@@ -0,0 +1,101 @@
+package Practice01;
+
+import java.time.LocalTime;
+import java.util.ArrayList;
+import java.util.Objects;
+
+public class User {
+
+ String userId;
+ String userPassword;
+ String userPhoneNumber;
+ String userEmail;
+ String userBirthDate;
+
+ ArrayList<String> electronicDevices =new ArrayList<>();
+ LocalTime registertime=LocalTime.now();//현재 시간 출력
+
+
+
+ public String toString(){
+ return "[User info] Id: " + userId+"PassWord: "+userPassword+"PhoneNumber: "
+ +userPhoneNumber+"Email: "+userEmail+"BirthDate: "+userBirthDate+
+ "Registertime: "+registertime+"electronicDevices: "+electronicDevices;
+ }
+
+ public String getUserId() {
+ return userId;
+ }
+
+ public void setUserId(String userId) {
+ this.userId = userId;
+ }
+
+ public String getUserPassword() {
+ return userPassword;
+ }
+
+ public void setUserPassword(String userPassword) {
+ this.userPassword = userPassword;
+ }
+
+ public String getUserPhoneNumber() {
+ return userPhoneNumber;
+ }
+
+ public void setUserPhoneNumber(String userPhoneNumber) {
+ this.userPhoneNumber = userPhoneNumber;
+ }
+
+ public String getUserEmail() {
+ return userEmail;
+ }
+
+ public void setUserEmail(String userEmail) {
+ this.userEmail = userEmail;
+ }
+
+ public String getUserBirthDate() {
+ return userBirthDate;
+ }
+
+ public void setUserBirthDate(String userBirthDate) {
+ this.userBirthDate = userBirthDate;
+ }
+
+ public ArrayList<String> getElectronicDevices() {
+ return electronicDevices;
+ }
+
+ public void setElectronicDevices(ArrayList<String> electronicDevices) {
+ this.electronicDevices = electronicDevices;
+ }
+
+ public LocalTime getRegistertime() {
+ return registertime;
+ }
+
+ public void setRegistertime(LocalTime registertime) {
+ this.registertime = registertime;
+ }
+
+ @Override
+ public int hashCode(){
+ return Objects.hash(electronicDevices, registertime, userBirthDate, userEmail, userId, userPassword,
+ userPhoneNumber);
+ }
+
+ @Override
+ public boolean equals(Object o) {
+ if (this == o) return true;
+ if (o == null || getClass() != o.getClass()) return false;
+ User u = (User) o;
+ return Objects.equals(electronicDevices, u.electronicDevices) &&
+ Objects.equals(registertime, u.registertime)&&
+ Objects.equals(userBirthDate, u.userBirthDate)&&
+ Objects.equals(userEmail, u.userEmail)&&
+ Objects.equals(userId, u.userId)&&
+ Objects.equals(userPassword, u.userPassword)&&
+ Objects.equals(userPhoneNumber, u.userPhoneNumber) ;
+ }
+}
diff --git a/Practice02/Users.java b/Practice02/Users.java
new file mode 100644
index 0000000..60d503a
--- /dev/null
+++ b/Practice02/Users.java
@@ -0,0 +1,84 @@
+package Practice02;
+
+import Practice01.User;
+
+import java.util.Arrays;
+
+//실습2. 객체 배열 `User[] userList`를 필드로 있는 `Users` 클래스를 작성하시오.
+// - 필드 - User[] userList (생성된 User 객체들을 모두 저장)
+// - 메소드 - 생성자, getter(), setter(), hashCode(), equals(), toString()
+public class Users {
+ private static User[] userslist;
+ private static Users singleton;
+ private Users(){
+ userslist =new User[10];
+ }
+
+ public User[] getUserslist() {
+ return userslist;
+ }
+
+ public void setUserslist(User[] userslist) {
+ this.userslist = userslist;
+ }
+
+ @Override
+ public int hashCode() {
+ return Arrays.hashCode(userslist);
+ }
+
+ @Override
+ public boolean equals(Object o) {
+ if (this == o) return true;
+ if (o == null || getClass() != o.getClass()) return false;
+ Users u = (Users) o;
+ return Arrays.equals(userslist, u.userslist);
+ }
+
+ @Override
+ public String toString() {
+ String s="";
+ for(int i=0;i<userslist.length;i++){
+ s+=userslist[i];
+ }
+ return s;
+ }
+
+ //2-1 Users 클래스의 객체를 싱글톤으로 생성하는 함수를 작성(Double Checked Locking 방식)
+
+ public Users getInstance(){
+ if(singleton==null){
+ synchronized (Users.class) {
+ if (singleton == null) {
+ singleton = new Users();
+ }
+ }
+ }
+ return singleton;
+ }
+
+ //2-2 회원 아이디 userId를 통해 인자로 주어진 회원번호에 해당하는 회원을 반환하는 함수를 작성
+ public User findByUserId(String userId){
+ for(int i=0; i<userslist.length;i++){
+ if(userslist[i].getUserId()==userId){
+ return userslist[i];
+ }
+ }
+ return null;
+ }
+
+
+ //2-3 인자로 주어진 회원 정보를 깊은 복사 (deepCopy - '실제 값'을 새로운 메모리 공간에 복사하는 것) 하는 함수를 작성
+ public User copy(User user){
+ User copy =new User();
+ copy.setUserId(user.getUserId());
+ copy.setUserPassword(user.getUserPassword());
+ copy.setUserEmail(user.getUserEmail());
+ copy.setUserBirthDate(user.getUserBirthDate());
+ copy.setUserPhoneNumber(user.getUserPhoneNumber());
+ copy.setElectronicDevices(user.getElectronicDevices());
+ copy.setRegistertime(user.getRegistertime());
+
+ return copy;
+ }
+}
diff --git a/Practice03/Electronics.java b/Practice03/Electronics.java
new file mode 100644
index 0000000..c98be0c
--- /dev/null
+++ b/Practice03/Electronics.java
@@ -0,0 +1,92 @@
+package Practice03;
+
+import Practice01.AuthMethod;
+import Practice01.Company;
+import Practice01.Electronic;
+import Practice02.Users;
+
+import java.util.*;
+import java.util.Arrays;
+
+public class Electronics {
+//- 객체 배열 `Electronic[] electronicList`를 필드로 가지고 있는 `Electronics`클래스를 작성하시오.
+// - 필드 - Electronic[] electronicList (생성된 Electronic 객체들을 모두 저장)
+// - 메소드 - 생성자, getter(), setter(), hashCode(), equals(), toString()
+ private static Electronic[] electroniclist;
+ private Electronics singleton;
+ private Electronics(){
+
+ }
+
+ public Electronic[] getElectroniclist() {
+ return electroniclist;
+ }
+
+ public void setElectroniclist(Electronic[] electroniclist) {
+ this.electroniclist = electroniclist;
+ }
+ @Override
+ public int hashCode() {
+ return Arrays.hashCode(electroniclist);
+ }
+
+ @Override
+ public boolean equals(Object o) {
+ if (this == o) return true;
+ if (o == null || getClass() != o.getClass()) return false;
+ Electronics e = (Electronics) o;
+ return Arrays.equals(electroniclist, e.electroniclist);
+ }
+
+ @Override
+ public String toString() {
+
+ return Arrays.toString(electroniclist);
+ }
+
+ //3-1 Electronic 클래스의 객체를 싱글톤으로 생성하는 함수를 작성(Double Checked Locking 방식)
+
+ public Electronics getInstance(){
+ if(singleton==null){
+ synchronized (Users.class) {
+ if (singleton == null) {
+ singleton = new Electronics();
+ }
+ }
+ }
+ return singleton;
+ }
+
+ //3-2 전자제품 일련번호 productNo를 통해 인자로 주어진 일련번호에 해당하는 전자제품을 반환하는 함수를 작성
+ public static Electronic findByProductNo(String productNo){
+ for(int i=0; i<electroniclist.length;i++){
+ if(electroniclist[i].getProductNo()==productNo){
+ return electroniclist[i];
+ }
+ }
+ return null;
+ }
+
+ //3-3 전자제품들 중 인자로 주어진 제조 회사를 찾아서 하나의 배열에 반환하는 함수를 작성
+ public static List<Electronic> groupByCompanyName(Company company){
+ List<Electronic> groupByCompanyNamelist =new ArrayList<>();
+ for(int i=0; i<electroniclist.length;i++){
+ if(electroniclist[i].getCompanyName().equals(company)){
+ groupByCompanyNamelist.add(electroniclist[i]);
+ }
+ }
+ return groupByCompanyNamelist;
+ }
+
+ //3-4 전자제품들 중 인자로 주어진 인증 방법을 찾아서 하나의 배열에 반환하는 함수를 작성
+ public static List<Electronic> groupByAuthMethod(AuthMethod authMethod){
+
+ List<Electronic> groupByAuthMethodlist =new ArrayList<>();
+ for(int i=0; i<electroniclist.length;i++){
+ if(electroniclist[i].getArrAuth().equals(authMethod)){
+ groupByAuthMethodlist.add(electroniclist[i]);
+ }
+ }
+ return groupByAuthMethodlist ;
+ }
+}