Java I'；我不会让循环在每次循环后都取一个新值吗？

我试图解决一个问题，我试图让我的循环在每次循环后取一个新值。这个程序应该是罚款我的利息支付，本金支付和当前余额，这样做我的利息应该是少一点，每次我循环，但它只是循环第一个答案超过一个周期

    Enter Loan Amount:500
    Enter Annual Interest:50
    Total payment:4
    Enter Loan Length :1
    Interest PaymentPrincipal PaymentCurrent Balance
    Interest Payment Principal Payment Current Balance 62.5
    62.5
    62.5
    62.5

这是第一个答案正确，但其他三个答案不正确的输出

    Enter Loan Amount:500
    Enter Annual Interest:50
    Total payment:4
    Enter Loan Length :1
    Interest PaymentPrincipal PaymentCurrent Balance
    Interest Payment Principal Payment Current Balance 62.5
    62.5
    62.5
    62.5

第一次付款后应为余额的12.5%

    Enter Loan Amount:500
    Enter Annual Interest:50
    Total payment:4
    Enter Loan Length :1
    Interest PaymentPrincipal PaymentCurrent Balance
    Interest Payment Principal Payment Current Balance 62.5
    62.5
    62.5
    62.5

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        //variabled decleared
        double rate;
        double payment;
        int amt = 1;
       //input
       System.out.print("Enter Loan Amount:");
        double principal = input.nextDouble();
        System.out.print("Enter Annual Interest:");
        double interest = input.nextDouble();
        System.out.print("Total payment:");//12=monthly,4= quartely,2=semi-annually and 1=annually
        double period = input.nextDouble();
        System.out.print("Enter Loan Length :");
        int length = input.nextInt();

        //proces
        rate = interest / 100;
        double period_rate = rate / period;
          double n = period * length;
        payment = (principal*Math.pow((1+period_rate),n))/n;





        System.out.printf("\n"+"Interest Payment"+"     Principal Payment       "+"         Current Balance     ");

        for(int i=1; i<=n; i++){
        double principal_payment=0;
        double current_balance;
        double payment_interest;

        current_balance=(principal-principal_payment);
         payment_interest=(principal*period_rate);
        principal_payment=(payment-payment_interest);
        principal=current_balance;



         System.out.println(payment_interest+"");

         }

publicstaticvoidmain（字符串[]args）{
扫描仪输入=新扫描仪（System.in）；
//可变的减少
双倍费率；
双倍支付；
国际金额=1；
//输入
系统输出打印（“输入贷款金额：”）；
double principal=input.nextDouble（）；
系统输出打印（“输入年度利息：”）；
双兴趣=输入。nextDouble（）；
System.out.print（“总付款：”；//12=每月，4=四分之一，2=半年，1=每年
双周期=input.nextDouble（）；
System.out.print（“输入贷款长度：”）；
int length=input.nextInt（）；
//过程
利率=利息/100；
双周期利率=利率/周期；
双n=周期*长度；
付款=（本金*数学功率（（1+期间费率），n））/n；
System.out.printf（“\n”+“利息支付”+“本金支付”+“当期余额”）；
for（int i=1；i对于for的所有迭代，您都给出了相同的值。这就是为什么您总是得到相同的输出

    Enter Loan Amount:500
    Enter Annual Interest:50
    Total payment:4
    Enter Loan Length :1
    Interest PaymentPrincipal PaymentCurrent Balance
    Interest Payment Principal Payment Current Balance 62.5
    62.5
    62.5
    62.5

如果每次都需要新的值，可以提示用户为每次迭代提供新的输入，也可以在for之前这样做，将输入存储在数组中，并在循环中处理它们

    Enter Loan Amount:500
    Enter Annual Interest:50
    Total payment:4
    Enter Loan Length :1
    Interest PaymentPrincipal PaymentCurrent Balance
    Interest Payment Principal Payment Current Balance 62.5
    62.5
    62.5
    62.5

类似于以下伪代码：

    Enter Loan Amount:500
    Enter Annual Interest:50
    Total payment:4
    Enter Loan Length :1
    Interest PaymentPrincipal PaymentCurrent Balance
    Interest Payment Principal Payment Current Balance 62.5
    62.5
    62.5
    62.5

for(i = 0; i < N; i++)
{
    //read principal from user input
    //read payment from user input
    // ect...
    payment_interest=(principal*period_rate);
    ...


}

（i=0；i
{
//从用户输入读取主体
//从用户输入读取付款
//等等。。。
付款利息=（本金*期间利率）；
...
}

---

您可以看到如何从键盘上读取Double。请注意，在循环中，您只需向用户询问可能会变化的参数。

忘记编程。拿上铅笔和纸，在几个月内完成计算。然后将这些计算转换为代码。当您开始编程时，您会超越自己在了解问题所在之前，请先进行rt编码。

尝试更改行：

    Enter Loan Amount:500
    Enter Annual Interest:50
    Total payment:4
    Enter Loan Length :1
    Interest PaymentPrincipal PaymentCurrent Balance
    Interest Payment Principal Payment Current Balance 62.5
    62.5
    62.5
    62.5

本金=当前余额

    Enter Loan Amount:500
    Enter Annual Interest:50
    Total payment:4
    Enter Loan Length :1
    Interest PaymentPrincipal PaymentCurrent Balance
    Interest Payment Principal Payment Current Balance 62.5
    62.5
    62.5
    62.5

致：

    Enter Loan Amount:500
    Enter Annual Interest:50
    Total payment:4
    Enter Loan Length :1
    Interest PaymentPrincipal PaymentCurrent Balance
    Interest Payment Principal Payment Current Balance 62.5
    62.5
    62.5
    62.5

本金=本金-本金支付

    Enter Loan Amount:500
    Enter Annual Interest:50
    Total payment:4
    Enter Loan Length :1
    Interest PaymentPrincipal PaymentCurrent Balance
    Interest Payment Principal Payment Current Balance 62.5
    62.5
    62.5
    62.5

或者将循环更改为：

    Enter Loan Amount:500
    Enter Annual Interest:50
    Total payment:4
    Enter Loan Length :1
    Interest PaymentPrincipal PaymentCurrent Balance
    Interest Payment Principal Payment Current Balance 62.5
    62.5
    62.5
    62.5

double current_balance = principal;
    for (int i = 1; i <= n; i++)
    {
        double principal_payment = 0;

        double payment_interest;

        //current_balance = (principal - principal_payment);
        payment_interest = (current_balance * period_rate);
        principal_payment = (payment - payment_interest);
        current_balance = current_balance - principal_payment;



        System.out.println(payment_interest + "");

    }

双流_余额=本金；
对于（int i=1；i）你的循环中没有任何变化。每次都会得到相同的结果。任何帮助都可以。我对编程很陌生这里的原则是什么？声明在哪里？你在计算“当前_平衡”，但它是循环中的局部（在循环中声明）它的价值不在任何地方使用。你基本上需要做的是更新“主体”在循环中。我刚刚编辑了它。我想在每次循环后找到每次付款的利息。我很了解我的计算，因为我确实使用笔和纸，因为我是新的，我不擅长循环，我卡在那个区域。回到笔和纸，看看你做了什么。给你计算的每个值命名。注意你“循环”的位置在纸上计算，以及你从一个迭代到下一个迭代的值。循环没有什么特别的——这不是一个神奇的公式。你只需要做你在纸上做的事情。真的，你的代码为我工作：输入贷款金额：500输入年利息：50总付款：4输入贷款长度：1利息支付本金付款活期余额62.5 45.28427124023437525.916576385498047 4.127919673919678一个问题，你怎么把它转到。2f