java - 添加将格式化值存储为数组下一行中的字符串的代码？

Question

我需要使用二维数组作为作业的一部分。

1. 我需要在行计数器的主方法开头声明变量以及提供 10 行和 4 列的矩形字符串数组

2. 在计算、格式化和显示每次计算结果的代码后面，添加将格式化值存储为数组下一行中的字符串的代码(您需要使用整数类的 toString 方法来存储年份值)。

我已经声明了一个 10x4 的数组和一个计数器变量， 但我在添加将格式化值存储为数组下一行中的字符串的代码时遇到问题(您需要使用整数类的 toString 方法来存储年份值)。

这是我在下面为这个问题(2)编写的代码，它似乎打印了一个空值列表，我如何让我的代码打印表格？在我看来，下面的代码是导致问题的代码，它是否正确？我有点困惑。

    FutureValueArray[counter][0] = Double.toString(monthlyInvestment);
    FutureValueArray[counter][1] = Double.toString(interestRate);
    FutureValueArray[counter][2] = Integer.toString(years);
    FutureValueArray[counter][3] = Double.toString(futureValue);

<小时/>

/*This is how my table should look like.
Inv/Mo. Rate Years Future Value
$100.00 8.0% 10 $18.416.57
$125.00 8.0% 10 $23,020.71*/


public static void main(String[] args)
{
    String[][] FutureValueArray = new String [10][4];
    int counter = 0;
    // display a welcome message
    System.out.println("Welcome to the Future Value Calculator");
    System.out.println();

    // perform 1 or more calculations
    Scanner sc = new Scanner(System.in);
    String choice = "y";
    while (choice.equalsIgnoreCase("y"))
    {

        // get the input from the user
        System.out.println("DATA ENTRY");
        double monthlyInvestment = getDoubleWithinRange(sc,
            "Enter monthly investment: ", 0, 1000);
        double interestRate = getDoubleWithinRange(sc,
            "Enter yearly interest rate: ", 0, 30);
        int years = getIntWithinRange(sc,
            "Enter number of years: ", 0, 100);

        // calculate the future value
        double monthlyInterestRate = interestRate/12/100;
        int months = years * 12;
        double futureValue = calculateFutureValue(
            monthlyInvestment, monthlyInterestRate, months);

        // get the currency and percent formatters
        NumberFormat currency = NumberFormat.getCurrencyInstance();
        NumberFormat percent = NumberFormat.getPercentInstance();
        percent.setMinimumFractionDigits(1);

        // format the result as a single string
        String results =
              "Monthly investment:\t"
                  + currency.format(monthlyInvestment) + "\n"
            + "Yearly interest rate:\t"
                  + percent.format(interestRate/100) + "\n"
            + "Number of years:\t"
                  +  years + "\n"
            + "Future value:\t\t"
                  + currency.format(futureValue) + "\n";

        // print the results
        System.out.println();
        System.out.println("FORMATTED RESULTS");
        System.out.println(results);

        FutureValueArray[counter][0] = Double.toString(monthlyInvestment);
        FutureValueArray[counter][1] = Double.toString(interestRate);
        FutureValueArray[counter][2] = Integer.toString(years);
        FutureValueArray[counter][3] = Double.toString(futureValue);
        for(int i = 0; i < FutureValueArray.length; i++)
        {
            for (int j = 0; j < FutureValueArray[i].length; j++)
                System.out.println(FutureValueArray[i][j] + " ");
            System.out.println("\n");
        }
        // see if the user wants to continue
        System.out.print("Continue? (y/n): ");
        choice = sc.next();
        counter++;
        System.out.println();
    }
}

Answer 1

你的代码看起来不错。

如果你改变

for(int i = 0; i < FutureValueArray.length; i++)

至

for(int i = 0; i <= counter; i++)

您不会打印尚未设置的 FutureValueArray 行的 null。

此外，您似乎想在该循环内使用 System.out.print() 函数，而不是 System.out.println() 函数。