尝试在Java中使用system.out.printf格式化双重数据类型

Question

I'm attempting to format a series of calculations into a table. So far I've gotten string data types to work, but double data types seem to behave differently. I get the format conversion errors when the program is run. I'm new to java, and any help would be greatly appreciated. I am trying to get it to look like this:

RATE    YEAR    AMOUNT ON DEPOSIT   INTEREST
----    ----    -----------------   --------
0.07     1        1,070.00          70.00
         2        1,144.90          144.90
         3        1,225.04          225.04
         4        1,310.80          310.80
         5        1,402.55          402.55
         6        1,500.73          500.73
         7        1,605.78          605.78
         8        1,718.19          718.19
         9        1,838.46          838.46
         10       1,967.15          967.15

Here is my code: ( I know that the loop is off if it's going to look like the above. I'm just trying to figure out how to format doubles first.)

import java.text.DecimalFormat;
public class interest
{
    public static void main(String[] args)
    {
        DecimalFormat money = new DecimalFormat("$#,##0.00");
        DecimalFormat percent = new DecimalFormat("0.00");
        double interest = 0;
        double principal = 1000;
        double rate7 = 0.07;
        double rate8 = 0.08;
        double rate9 = 0.09;
        double rate10 = 0.10;
        double endYear = 0;
        int yearCount = 1;
        System.out.printf("%1s%7s%20s%10s", "Rate", "Year", "Amount on Deposit" , "Interest");
        System.out.println();
        System.out.printf("%1s%7s%20s%10s", "----", "----", "-----------------", "--------");
        System.out.println();
        boolean firstTime =true;
        while (yearCount <= 10)
        {
            if(firstTime)
            {  //the issue is here
                System.out.printf("1f%7d%20f%10f", "percent.format(rate7)", "yearCount","endYear", "interest");
                firstTime = false;
            }
            else
            {
                endYear = principal * Math.pow((1 + rate7),yearCount);
                System.out.println(money.format(endYear));
                yearCount++;
                interest = endYear - 1000;
                System.out.println();
            }
        }
        System.out.format("%1s%7s%20s%10s", "Rate", "Year", "Amount on Deposit" , "Interest");
        System.out.println();
        System.out.format("%1s%7s%20s%10s", "----", "----", "-----------------", "--------");
        System.out.println();
        yearCount = 1;
        endYear = 0;
        interest = 0;
        firstTime = true;
        while (yearCount <= 10)
        {
            if(firstTime)
            {
                System.out.println(percent.format(rate8));
                firstTime = false;
            }
            else
            {
                endYear = principal * Math.pow((1 + rate8),yearCount);
                yearCount++;
                interest = endYear - 1000;
                System.out.println(money.format(endYear));
            }
        }
        System.out.format("%1s%7s%20s%10s", "Rate", "Year", "Amount on Deposit" , "Interest");
        System.out.println();
        System.out.format("%1s%7s%20s%10s", "----", "----", "-----------------", "--------");
        System.out.println();
        yearCount = 1;
        endYear = 0;
        interest = 0;
        firstTime = true;
        while (yearCount <= 10)
        {
            if(firstTime)
            {
                System.out.println(percent.format(rate9));
                firstTime = false;
            }
            else
            {
                endYear = principal * Math.pow((1 + rate9),yearCount);
                yearCount++;
                interest = endYear - 1000;
                System.out.println(money.format(endYear));
                System.out.println();
            }
        }
        System.out.format("%1s%7s%20s%10s", "Rate", "Year", "Amount on Deposit" , "Interest");
        System.out.println();
        System.out.format("%1s%7s%20s%10s", "----", "----", "-----------------", "--------");
        System.out.println();
        yearCount = 1;
        endYear = 0;
        interest = 0;
        firstTime = true;
        while (yearCount <= 10)
        {
            if(firstTime)
            {
                System.out.println(percent.format(rate10));
                firstTime = false;
            }
            else
            {
                endYear = principal * Math.pow((1 + rate10),yearCount);
                yearCount++;
                interest = endYear - 1000;
                System.out.println(money.format(endYear));
                System.out.println();
            }

        }
    }
}

Answer 1

Replace

    System.out.format("%1s%7s%20s%10s", "Rate", "Year", "Amount on Deposit" , "Interest");

with

    System.out.printf("%s %7d %20f %10f", percent.format(rate7), yearCount, endYear, interest);

As you passing strings not numbers. Also, for the first string element, you are not specifying '%s'. Once you replace it, your code will work fine