Java ATM程序
我正在做一个atm程序，我很难弄清楚如何让它实际存入和取出。 余额自动以$ 0开始，但是我无法得到任何我输入的东西来实际添加或减去它我做错了什么？
public class ATM { static Scanner keyboard = new Scanner(System.in); static String acctNum, pwd, result; static double oldBalance, newBalance, deposit, withdraw; static int choose; public static void main(String[] args) { for (int run = 0; run < 3; run++) { System.out.println("Enter your account number"); acctNum = keyboard.nextLine(); System.out.println("Enter your account password"); pwd = keyboard.nextLine(); result = checkID(acctNum, pwd); if (!result.equals("ERROR")) { break; } else if (run == 2) {// you cannot try to log in anymore than 3 // times System.out.println("MAXIMUM TRIES EXCEEDED"); return; } } menu(); } public static String checkID(String acctNum, Object pwd) { String result = "ERROR"; String a = "44567-5 mypassword 520.36"; String b = "1234567-6 anotherpassword 48.20"; String c = "4321-0 betterpassword 96.74"; if (acctNum.equals("44567-5") && pwd.equals("mypassword")) { result = "520.36"; } else if (acctNum.equals("1234567-6") && pwd.equals("anotherpassword")) { result = "48.20"; } else if (acctNum.equals("4321-0") && pwd.equals("betterpassword")) { result = "96.74"; } System.out.println(result); return result; } public static int menu() { System.out .println("Choose one of the following: \n1.Display Balance\n2.Deposit\n3.Withdraw\n4.Log Out"); choose = keyboard.nextInt(); if (choose == 1) {// 1. Display Balance displayBalance(); menu(); return 1; } if (choose == 2) {// 2. Deposit deposit(); menu(); return 2; } if (choose == 3) {// 3. Withdraw withdraw(); menu(); return 3; } if (choose == 4) {// 4. Log out System.out.println("You are logged out."); return 4; } if (choose = 1) {// type in anything less than 1 and you will get a // system error System.out.println("System Error"); menu(); return 6; } return choose; } public static double deposit() { System.out.println("How much would you like to deposit?"); deposit = keyboard.nextInt(); System.out.println((deposit + oldBalance)==newBalance);// deposit money into balance return 2; } public static double displayBalance() { System.out.println("Total balance is: $" + oldBalance); oldBalance = 0.00; return 1; } public static double withdraw() { System.out.println("How much would you like to withdraw?"); withdraw = keyboard.nextInt(); System.out.println(newBalance + withdraw);// withdraw money from balance return 3; } }
一些观察：
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您的class级不应将oldBalance，deposit和withdraw声明为全局变量。 提款方法不应该访问存款变量，反之亦然。 尽可能多地限制变量的范围是一种很好的编程习惯。 因为在此方法之外并不真正需要“存放”变量，所以绝对没有理由将其变为全局变量。 关于“当前的平衡”，不能说同样的话。 这个类的所有方法都需要这个变量：deposit，withdraw，displayBalance等。因此，有一个很好的理由让它成为全局的（但是，如果你能用较小的范围解决问题，你应该这样做）。
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我不明白为什么
deposit()和withdrawal()需要返回任何东西。
deposit()和withdrawal()的最简单实现是简单地将用户输入添加到currentBalance并将其保存在currentBalance 。
public void deposit() { Scanner input = new Scanner(System.in); System.out.printn("Enter deposit amount: ); double amount = input.nextDouble(); System.out.println("Your deposit amount: " + amount); currentBalance += amount; System.out.println("Your new balance is: + currentBalance); } public void withdrawal() { Scanner input = new Scanner(System.in); System.out.printn("Enter withdrawal amount: ); double amount = input.nextDouble(); System.out.println("Your withdrawal amount: " + amount); currentBalance -= amount; System.out.println("Your new balance is: + currentBalance); }
你永远不会保存当前的余额。 ==运算符是比较运算符，而不是赋值运算符。 当你做这样的事情时：
System.out.println((deposit + oldBalance)==newBalance);
或者像这样：
System.out.println(newBalance + withdraw);
您所做的只是将值传递给println()方法，而不是更新应该保存余额的变量。 实际上，第一个应该打印为false （除非deposit和oldBalance都为零）。 如果你看一下我的代码示例， currentBalance += amount; 是currentBalance = currentBalance + amount;简写currentBalance = currentBalance + amount; 这意味着“将此amount添加到currentBalance并将其存储在currentBalance 。因为我正在重用currentBalance，所以我不再需要oldBalance变量。
完整运行代码
import java.awt.Container; import java.awt.FlowLayout; import java.awt.GridLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.WindowEvent; import java.awt.event.WindowAdapter; import java.io.IOException; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JOptionPane; import javax.swing.JPanel; import javax.swing.JTextArea; import java.util.ArrayList; import java.util.Scanner; /** A simulation of an automatic teller machine */ public class ATM { static Scanner keyboard = new Scanner(System.in); static String acctNum, pwd, result; static double oldBalance, newBalance, deposit, withdraw,currentBalance; static int choose; public static void main(String[] args) { for (int run = 0; run < 3; run++) { System.out.println("Enter your account number"); acctNum = keyboard.nextLine(); System.out.println("Enter your account password"); pwd = keyboard.nextLine(); result = checkID(acctNum, pwd); if (!result.equals("ERROR")) { break; } else if (run == 2) {// you cannot try to log in anymore than 3 // times System.out.println("MAXIMUM TRIES EXCEEDED"); return; } } menu(); } public static String checkID(String acctNum, Object pwd) { String result = "ERROR"; String a = "44567-5 mypassword 520.36"; String b = "1234567-6 anotherpassword 48.20"; String c = "4321-0 betterpassword 96.74"; if (acctNum.equals("2345") && pwd.equals("2345")) { result = "520.36"; } else if (acctNum.equals("1234567-6") && pwd.equals("anotherpassword")) { result = "48.20"; } else if (acctNum.equals("4321-0") && pwd.equals("betterpassword")) { result = "96.74"; } System.out.println(result); return result; } public static int menu() { System.out.println("Choose one of the following: \n1.Display Balance\n2.Deposit\n3.Withdraw\n4.Log Out"); choose = keyboard.nextInt(); if (choose == 1) {// 1. Display Balance displayBalance(); menu(); return 1; } if (choose == 2) {// 2. Deposit deposit(); menu(); return 2; } if (choose == 3) {// 3. Withdraw withdraw(); menu(); return 3; } if (choose == 4) {// 4. Log out System.out.println("You are logged out."); return 4; } if (choose <= 5) {// type in anything greater than 4 and you will get a // system error System.out.println("System Error"); menu(); return 5; } if (choose >= 1) {// type in anything less than 1 and you will get a // system error System.out.println("System Error"); menu(); return 6; } return choose; } public static void deposit() { Scanner input = new Scanner(System.in); System.out.println("Enter deposit amount:"); double amount = input.nextDouble(); System.out.println("Your deposit amount: " + amount); currentBalance += amount; System.out.println("Your new balance is: " + currentBalance); } public static double displayBalance() { System.out.println("Total balance is: $" + currentBalance); oldBalance = 0.00; return 1; } public static void withdraw() { Scanner input = new Scanner(System.in); System.out.println("Enter withdrawal amount: "); double amount = input.nextDouble(); System.out.println("Your withdrawal amount: " + amount); currentBalance -= amount; System.out.println("Your new balance is: " + currentBalance); } }
package shraam.bank.atm; import java.util.HashMap; import java.util.Map; import java.util.Scanner; import java.util.logging.Level; public class CalculateMoneyAtm { static Integer initialtwothousandrupees = 0; static Integer initialhundressrupees = 0; static Integer initialfiftyrupees = 0; static Integer initialtenrupees = 0; static Integer twothousandrupees = 0; static Integer hundressrupees = 0; static Integer fiftyrupees = 0; static Integer tenrupees = 0; static Integer totalAmount = 0; public static void main(String[] args) { ATMStatus atmStatus = new ATMStatus(); getMoney(atmStatus); }//end of psvm public static void reRun(ATMStatus atmStatus) { MyLog.logit().info("Would u like to credit more money ? y/n"); System.out.println("Would u like to credit more money ? y/n "); Scanner input = new Scanner(System.in); String choice = input.nextLine(); if (choice.equals("y") || choice.equals("Y")) { getMoney(atmStatus); } if (choice.equals("n") || choice.equals("N")) { System.exit(1); } else { MyLog.logit().log(Level.SEVERE, "Invalid Input :"+choice); System.out.println("Invalid Input"); } reRun(atmStatus); } public static void getMoney(ATMStatus atmStatus) { twothousandrupees = 0; hundressrupees = 0; fiftyrupees = 0; tenrupees = 0; totalAmount = 0; Integer amountInt=0; System.out.println("Currency Avaialbe in ATM"); for (String key : atmStatus.getAvaialableMoney().keySet()) { System.out.println(atmStatus.getAvaialableMoney().get(key) + ":" + key + " Notes"); } for (String key : atmStatus.getAvaialableMoney().keySet()) { if (key.equals("2000")) initialtwothousandrupees = atmStatus.getAvaialableMoney().get(key); if (key.equals("100")) initialhundressrupees = atmStatus.getAvaialableMoney().get(key); if (key.equals("50")) initialfiftyrupees = atmStatus.getAvaialableMoney().get(key); if (key.equals("10")) initialtenrupees = atmStatus.getAvaialableMoney().get(key); } Scanner input = new Scanner(System.in); System.out.print("Enter Money > "); String amount = input.nextLine(); try { try{ amountInt = Integer.parseInt(amount); if(amountInt%10!=0) { System.out.println("Please enter amount in multiple of 10 "); reRun(atmStatus); } }catch(NumberFormatException ne){ MyLog.logit().log(Level.SEVERE, ne.getMessage()); } System.out.print("Required Amount : "); System.out.println(amount); totalAmount = ((initialtwothousandrupees * 2000) + (initialhundressrupees * 100) + (initialfiftyrupees * 50) + (initialtenrupees * 10)); System.out .println("Total Available amount in ATM : " + totalAmount); if (totalAmount < amountInt) { System.out .println("Total Avaialble amount is less in atm, Sorry for Inconvience"); reRun(atmStatus); } while (amountInt >= 2000 && initialtwothousandrupees > 0) { initialtwothousandrupees = initialtwothousandrupees - 1; twothousandrupees++; amountInt = amountInt - 2000; } while (amountInt >= 100 && initialhundressrupees > 0) { initialhundressrupees = initialhundressrupees - 1; hundressrupees++; amountInt = amountInt - 100; } while (amountInt >= 50 && initialfiftyrupees > 0) { initialfiftyrupees = initialfiftyrupees - 1; fiftyrupees++; amountInt = amountInt - 50; } while (amountInt >= 10 && initialtenrupees > 0) { initialtenrupees = initialtenrupees - 1; tenrupees++; amountInt = amountInt - 10; } if (amountInt > 0) { System.out.println("No avalable balance in this unit"); reRun(atmStatus); } else { System.out.println("Plz take your money in currency"); Map avaialableMoney = new HashMap(); System.out.println(" No of 2000:"+ twothousandrupees); System.out.println(" No of 100:"+ hundressrupees); System.out.println(" No of 50:"+ fiftyrupees); System.out.println(" No of 10:"+ tenrupees); avaialableMoney.put("2000", (initialtwothousandrupees)); avaialableMoney.put("100", (initialhundressrupees)); avaialableMoney.put("50", (initialfiftyrupees)); avaialableMoney.put("10", (initialtenrupees)); atmStatus.setAvaialableMoney(avaialableMoney); } //return amountInt; } catch (Exception e) { MyLog.logit().log(Level.SEVERE, e.getMessage()); } System.out.println("Take your Amount = "+(2000*twothousandrupees+100*hundressrupees+50*fiftyrupees+10*tenrupees)); reRun(atmStatus); }//end of getMoney } package shraam.bank.atm; import java.util.HashMap; import java.util.Map; import java.util.logging.Level; public class ATMStatus { public Map avaialableMoney=new HashMap(); public ATMStatus(){ MyLog.logit().log(Level.INFO, " ATMStatus Initialized"); avaialableMoney.put("2000", 10); avaialableMoney.put("100", 10); avaialableMoney.put("50", 10); avaialableMoney.put("10", 10); } public Map getAvaialableMoney() { return this.avaialableMoney; } public void setAvaialableMoney(Map avaialableMoney) { this.avaialableMoney = avaialableMoney; } } package shraam.bank.atm; import java.io.IOException; import java.util.logging.FileHandler; import java.util.logging.Logger; import java.util.logging.SimpleFormatter; public class MyLog { public static Logger logit() { Logger logger = Logger.getLogger("MyLog"); FileHandler fh; try { // This block configure the logger with handler and formatter fh = new FileHandler("C:/ArunTest/temp/MyLogFile.log"); logger.addHandler(fh); SimpleFormatter formatter = new SimpleFormatter(); fh.setFormatter(formatter); // the following statement is used to log any messages logger.info("My first log"); } catch (SecurityException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } return logger; } } // output: Nov 27, 2016 10:43:48 PM shraam.bank.atm.MyLog logit INFO: My first log Nov 27, 2016 10:43:48 PM shraam.bank.atm.ATMStatus SEVERE: ATMStatus Currency Avaialbe in ATM 10:100 Notes 10:2000 Notes 10:50 Notes 10:10 Notes Enter Money > 540 Required Amount : 540 Total Available amount in ATM : 21600 Plz take your money in currency No of 2000:0 No of 100:5 No of 50:0 No of 10:4 Take your Amount = 540 Nov 27, 2016 10:43:52 PM shraam.bank.atm.MyLog logit INFO: My first log Nov 27, 2016 10:43:52 PM shraam.bank.atm.CalculateMoneyAtm reRun INFO: Would u like to credit more money ? y/n Would u like to credit more money ? y/ny Currency Avaialbe in ATM 5:100 Notes 10:2000 Notes 10:50 Notes 6:10 Notes Enter Money > 2060 Required Amount : 2060 Total Available amount in ATM : 21060 Plz take your money in currency No of 2000:1 No of 100:0 No of 50:1 No of 10:1 Take your Amount = 2060 Nov 27, 2016 10:44:04 PM shraam.bank.atm.MyLog logit INFO: My first log Nov 27, 2016 10:44:04 PM shraam.bank.atm.CalculateMoneyAtm reRun INFO: Would u like to credit more money ? y/n Would u like to credit more money ? y/n