Java 银行账户计划
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原文地址: http://stackoverflow.com/questions/19275389/
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Bank Account Program
提问by Morgan
I am working on making a program to simulate bank transactions. I have to ask the user if they want to deposit, withdrawal, or transfer.
我正在制作一个程序来模拟银行交易。我必须询问用户是否要存款、取款或转账。
When I deposit a certain amount (for example 1000), it says my balance is 1000. Then I ask to withdrawal a number like 400 it says my balance is -400. After all that I thought maybe I have to check my balance and then it will give me the correct balance of what should be 600, but it says 0. For instance, see this transcript:
当我存入一定金额（例如 1000）时，它说我的余额是 1000。然后我要求提款 400 之类的数字，它说我的余额是 -400。毕竟我想也许我必须检查我的余额，然后它会给我应该是 600 的正确余额，但它显示 0。例如，请参阅此成绩单：
I was thinking because in my code (shown below) I made the balance = 0 but if I take the = 0 away and try to run the program it says it needs to be initialized.
我在想，因为在我的代码（如下所示）中，我设置了 balance = 0 但如果我把 = 0 拿走并尝试运行程序，它会说它需要初始化。
I am stuck and I want to figure it out. Please don't post the entire code corrected. I want to fix it myself and learn!
我被卡住了，我想弄清楚。请不要发布更正的整个代码。我想自己修好学习！
import java.util.Scanner;
public class BankTransactions {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int num;
do {
double balance = 0;
double amount;
System.out.println("Type Number");
System.out.println("1. Deposit");
System.out.println("2. Withdrawal");
System.out.println("3. Balance");
System.out.println("4. Exit");
num = scan.nextInt();
if (num == 1) {
System.out.println("Enter amount to deposit: ");
amount = scan.nextDouble();
// Add the amount to the balance
balance += amount;
System.out.println("Your balance is");
System.out.println(balance);
} else if (num == 2) {
System.out.println("Enter amount to withdrawal: ");
amount = scan.nextDouble();
// Remove the amount from the balance
balance -= amount;
System.out.println("Your balance is");
System.out.println(balance);
} else if (num == 3) {
System.out.println("Your Balance");
System.out.println(balance);
}
} while (num != 4);
System.out.println("Good Bye!");
}
}
采纳答案by luanjot
Every time the do{...} while{...} is executed, you are setting balance=0. You should take it out the loop.
每次执行 do{...} while{...} 时，您都设置 balance=0。你应该把它从循环中取出来。
double balance = 0;
do{
...
回答by Tom Swifty
You are initializing balance to 0 within the do loop, so it resets to zero each time around.
您在 do 循环中将 balance 初始化为 0，因此每次都会重置为零。
Move the line balance = 0 to above the while loop.
将行 balance = 0 移动到 while 循环上方。
回答by Bucket
Every time you run the loop you set balanceto 0. Move this to outside your doloop:
每次运行循环时都设置balance为0. 将其移至do循环之外：
double balance = 0;
double amount;
do {
/* code */
} while(num != 4);
