Java programming 자바 프로그래밍 실습 : 은행 계좌 ATM

Java programming 자바 프로그래밍 실습 : 은행 계좌 ATM

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2021-1 성균관대학교 소프트웨어학과 타메르 교수님의 자바 프로그래밍 실습 수업을 들으면서 수행한 예제입니다. 

 

Mini project (ATM)

구현해야할 것 

• BankAccount 클래스
  • String FullName
  • String Username
  • String Password
  • Double Balance
  • String LastOperation
  • constructor 만들어서 초기화
• main 메소드에서 BankAccount 객체 3개

BankAccount account1 = new BankAccount("Firuz", "firuz", "p@ssw@rd", 2000.0, "");
BankAccount account2 = new BankAccount("Kang Seong", "kang", "p@ssw@rd123", 34000.0, "");
BankAccount account3 = new BankAccount("SiHyein Ryu", "ryu", "p@ssw@rd1234", 10000.0, "");

• 로그인 기능 : 로그인 성공할 때까지 반복해서 username, password 입력 받기 

• 로그인 성공 후, 메인 메뉴 보여주기 - 사용자가 0 입력하기 전까지 반복 수행 

• 각 메뉴에 맞기 기능 구현하기 

 

(1) 계좌 확인

(2) 인출

인출하려는 돈이 계좌의 balance보다 큰 금액이면 "Withdrawal amount exceeded account balance" 출력

 

(3) 마지막 거래 정보 확인

 

(0) 작업 종료

 

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• BankAccount.java

public class BankAccount {
	public String fullName;
	public String username;
	public String password;
	public double balance;
	public String lastOperation;
	
	// constructor
	public BankAccount(String fullName, String username, String password, double balance, String lastOperation) {
		super();
		setFullName(fullName);
		setUsername(username);
		setPassword(password);
		setBalance(balance);
		setLastOperation(lastOperation);
		
	}
	
	// getter and setter for each data fields
	public String getFullName() {
		return fullName;
	}



	public void setFullName(String fullName) {
		this.fullName = fullName;
	}



	public String getUsername() {
		return username;
	}



	public void setUsername(String username) {
		this.username = username;
	}



	public String getPassword() {
		return password;
	}



	public void setPassword(String password) {
		this.password = password;
	}



	public double getBalance() {
		return balance;
	}



	public void setBalance(double balance) {
		this.balance = balance;
	}



	public String getLastOperation() {
		return lastOperation;
	}



	public void setLastOperation(String lastOperation) {
		this.lastOperation = lastOperation;
	}



	public static void main(String[] args) {
		
		ATM atm = new ATM();
		
		// create three BankAccount instance
		BankAccount account1 = new BankAccount("Firuz", "firuz", "p@ssw@rd", 2000.0, "");
		BankAccount account2 = new BankAccount("Kang Seong", "kang", "p@ssw@rd123", 34000.0, "");
		BankAccount account3 = new BankAccount("SiHyein Ryu", "ryu", "p@ssw@rd1234", 10000.0, "");
		
		// create BankAccount array
		BankAccount[] BankAccountList = {account1, account2, account3};

		atm.Login(BankAccountList);	

	}

}

 

• ATM.java

import java.util.Scanner;

public class ATM {
	
	public void CheckBalance(BankAccount account) {
		System.out.println("User: " + account.getUsername());
		System.out.println("Balance: " + account.getBalance());
		account.setLastOperation("Check balance");
	}
	
	public void WithdrawMoney(BankAccount account) {
		
		double amount;	
		Scanner input = new Scanner(System.in);
		System.out.print("Enter amount: ");
		amount = input.nextDouble();
		
		if (account.getBalance() >= amount) {
			account.setBalance(account.getBalance() - amount);
		}
		else {
			System.out.println("Withdrawal amount exceeded account balance.");
		}
		account.setLastOperation("Withdrawal");
		
//		input.close();
	}
	
	public void LastOperation(BankAccount account) {
		System.out.println("Name: " + account.getFullName());
		System.out.println("Current Balance: " + account.getBalance());
		System.out.println("Last Operation: " + account.getLastOperation());
	}

	public void Operation (BankAccount account) {
		
		int op = 10;

		Scanner input = new Scanner(System.in);
		
		// repeatedly asking and performing operations until user enters 0
		while (op != 0) {
			System.out.println("1. Check balance (Enter 1);\n"
					+ "2. Withdraw money (Enter 2);\n"
					+ "3. Last Operation (Enter 3);\n"
					+ "4. Exit (Enter 0);"
					);
					
			op = input.nextInt();
			
			// call correct method for operation number that user enters
			if (op == 1) {
				this.CheckBalance(account);
			}
			else if (op == 2) {
				this.WithdrawMoney(account);
			}
			else if (op == 3) {
				this.LastOperation(account);
			}
		}
		

		input.close();
		
		System.out.println("Thank you for banking with us!");		
		
	}
	
	public void Login(BankAccount[] List) {
		System.out.println("Login");
		
		String un;
		String pw;
		int i;
		int result;
		BankAccount currentUser = null;
		
		// 0 means success, -1 means failure
		result = -1;
		
		Scanner input = new Scanner(System.in);
		
		// repeat input user name and password until result is success
		while (result != 0) {

			System.out.print("Username:");
			un = input.next();
			System.out.print("Password: ");
			pw = input.next();
			
			// check user name and password if it is in the BankAccount list and is correct.
			for ( i=0 ; i<List.length; i++ ) {
				// if it's correct, set result as 0 (success) and break for loop
				if (List[i].getUsername().equals(un) && List[i].getPassword().equals(pw) ) {
					result = 0;
					break;
				}
				else {
					continue;
				}
			}
			
			// before escape while loop, if result is 0, set currentUser who log in.
			if (result == 0) {
				currentUser = List[i];
				break;
			}
		}	
		
		// if currentUser is not null, it means that login success.
		// then show operations for currentUser
		if ( currentUser != null ) {
			
			this.Operation(currentUser);
		}
		
		input.close();	
		
	}

}

withdraw 메소드에서 Scanner input을 close하면 2번 입력하고 작업 완료 후 에러가 난다. 왜지?