Java 我在格式化程序中的输出时遇到问题

代码格式不正确

起初，当我想要1.00时，代码会吐出1.0。所以，我用了一个if语句来解决这个问题。然后代码会给出.5而不是.50，所以我尝试了相同的解决方案，但没有成功。我想知道我是否可以制作一个格式化程序，如果小数点右边只有一个数字，它会额外添加一个0来解决我的问题

    import java.util.Scanner;

public class addCoins {
    public static void main(String[] args) {
        int quarters, dimes, nickels, pennies;

        Scanner input = new Scanner(System.in);

        System.out.println("Enter in your total coins: ");

        System.out.println();

        System.out.print("Quarters: ");
        quarters = input.nextInt();
        System.out.print("Dimes: ");
        dimes = input.nextInt();
        System.out.print("Nickels: ");
        nickels = input.nextInt();
        System.out.print("Pennies: ");
        pennies = input.nextInt();

        System.out.println();

        System.out.println(dollarAmount(quarters, dimes, nickels, pennies));
    }

    public static String dollarAmount(int quarters2, int dimes2, int nickels2, int pennies2) {

        double total = (quarters2 * .25) + (dimes2 * .10) + (nickels2 * .05) + (pennies2 * .01);

        if (total % 1.0 == 0 || total % .10 == .0) {
            return "Total: $" + total + "0";
        } else {
            return "Total: $" + total;
        }
    }

}

.5而不是在您的特定情况下的.50（您的方法是返回字符串），一种方法是使用@Taslim所涉及的方法，它如下所示：

public static String dollarAmount(int quarters2, int dimes2, int nickels2, int pennies2) {
    double total = (quarters2 * .25) + (dimes2 * .10) + (nickels2 * .05) + (pennies2 * .01);
    return String.format("Total: $%.2f", total);
}

public static String dollarAmount(int quarters2, int dimes2, int nickels2, int pennies2) {
    double total = (quarters2 * .25) + (dimes2 * .10) + (nickels2 * .05) + (pennies2 * .01);
    DecimalFormat df = new DecimalFormat(".##", DecimalFormatSymbols.getInstance(Locale.US));
    return "Total: $" + df.format(total);
}

public static String dollarAmount(int quarters2, int dimes2, int nickels2, int pennies2) {
    double total = (quarters2 * .25) + (dimes2 * .10) + (nickels2 * .05) + (pennies2 * .01);

    long factor = (long) Math.pow(10, 2); // 2 is the decimal places
    total = total * factor;
    long tmp = Math.round(total);
    return "Total: $" + String.valueOf((double) tmp / factor);
}

public static String dollarAmount(int quarters2, int dimes2, int nickels2, int pennies2) {
    double total = (quarters2 * .25) + (dimes2 * .10) + (nickels2 * .05) + (pennies2 * .01);

    BigDecimal bd = new BigDecimal(total);
    // The 2 used below is the decimal places. You can
    // use whatever rounding mode you want.
    bd = bd.setScale(2, RoundingMode.HALF_UP); 
    return "Total: $" + String.valueOf(bd.doubleValue());

}

另一种方法是利用@Jens已经提到的方法，它会是这样的：

public static String dollarAmount(int quarters2, int dimes2, int nickels2, int pennies2) {
    double total = (quarters2 * .25) + (dimes2 * .10) + (nickels2 * .05) + (pennies2 * .01);
    return String.format("Total: $%.2f", total);
}

public static String dollarAmount(int quarters2, int dimes2, int nickels2, int pennies2) {
    double total = (quarters2 * .25) + (dimes2 * .10) + (nickels2 * .05) + (pennies2 * .01);
    DecimalFormat df = new DecimalFormat(".##", DecimalFormatSymbols.getInstance(Locale.US));
    return "Total: $" + df.format(total);
}

public static String dollarAmount(int quarters2, int dimes2, int nickels2, int pennies2) {
    double total = (quarters2 * .25) + (dimes2 * .10) + (nickels2 * .05) + (pennies2 * .01);

    long factor = (long) Math.pow(10, 2); // 2 is the decimal places
    total = total * factor;
    long tmp = Math.round(total);
    return "Total: $" + String.valueOf((double) tmp / factor);
}

public static String dollarAmount(int quarters2, int dimes2, int nickels2, int pennies2) {
    double total = (quarters2 * .25) + (dimes2 * .10) + (nickels2 * .05) + (pennies2 * .01);

    BigDecimal bd = new BigDecimal(total);
    // The 2 used below is the decimal places. You can
    // use whatever rounding mode you want.
    bd = bd.setScale(2, RoundingMode.HALF_UP); 
    return "Total: $" + String.valueOf(bd.doubleValue());

}

使用DecimalFormat变量初始化中看到的值，以便您的数值以特定国家/地区的数字格式显示

对于较小的值，另一种更冗长的方法是利用和这样的方法：

public static String dollarAmount(int quarters2, int dimes2, int nickels2, int pennies2) {
    double total = (quarters2 * .25) + (dimes2 * .10) + (nickels2 * .05) + (pennies2 * .01);
    return String.format("Total: $%.2f", total);
}

public static String dollarAmount(int quarters2, int dimes2, int nickels2, int pennies2) {
    double total = (quarters2 * .25) + (dimes2 * .10) + (nickels2 * .05) + (pennies2 * .01);
    DecimalFormat df = new DecimalFormat(".##", DecimalFormatSymbols.getInstance(Locale.US));
    return "Total: $" + df.format(total);
}

public static String dollarAmount(int quarters2, int dimes2, int nickels2, int pennies2) {
    double total = (quarters2 * .25) + (dimes2 * .10) + (nickels2 * .05) + (pennies2 * .01);

    long factor = (long) Math.pow(10, 2); // 2 is the decimal places
    total = total * factor;
    long tmp = Math.round(total);
    return "Total: $" + String.valueOf((double) tmp / factor);
}

public static String dollarAmount(int quarters2, int dimes2, int nickels2, int pennies2) {
    double total = (quarters2 * .25) + (dimes2 * .10) + (nickels2 * .05) + (pennies2 * .01);

    BigDecimal bd = new BigDecimal(total);
    // The 2 used below is the decimal places. You can
    // use whatever rounding mode you want.
    bd = bd.setScale(2, RoundingMode.HALF_UP); 
    return "Total: $" + String.valueOf(bd.doubleValue());

}

但是，对于更大、更复杂的值，您可能希望在使用浮点或双数据类型值（）进行计算时，使用可提供更高精度的方法来进行计算。。类似于以下内容：

public static String dollarAmount(int quarters2, int dimes2, int nickels2, int pennies2) {
    double total = (quarters2 * .25) + (dimes2 * .10) + (nickels2 * .05) + (pennies2 * .01);
    return String.format("Total: $%.2f", total);
}

public static String dollarAmount(int quarters2, int dimes2, int nickels2, int pennies2) {
    double total = (quarters2 * .25) + (dimes2 * .10) + (nickels2 * .05) + (pennies2 * .01);
    DecimalFormat df = new DecimalFormat(".##", DecimalFormatSymbols.getInstance(Locale.US));
    return "Total: $" + df.format(total);
}

public static String dollarAmount(int quarters2, int dimes2, int nickels2, int pennies2) {
    double total = (quarters2 * .25) + (dimes2 * .10) + (nickels2 * .05) + (pennies2 * .01);

    long factor = (long) Math.pow(10, 2); // 2 is the decimal places
    total = total * factor;
    long tmp = Math.round(total);
    return "Total: $" + String.valueOf((double) tmp / factor);
}

public static String dollarAmount(int quarters2, int dimes2, int nickels2, int pennies2) {
    double total = (quarters2 * .25) + (dimes2 * .10) + (nickels2 * .05) + (pennies2 * .01);

    BigDecimal bd = new BigDecimal(total);
    // The 2 used below is the decimal places. You can
    // use whatever rounding mode you want.
    bd = bd.setScale(2, RoundingMode.HALF_UP); 
    return "Total: $" + String.valueOf(bd.doubleValue());

}

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你挑吧；）

看看DecimalFormat@Jens，我认为这会起作用，但有一个问题。由于附加了字符串，我无法设置总计的格式。我不允许删除字符串，因为我的老师说我需要在返回中添加“Total:$”。你可以在String.format（）方法中使用字符格式化程序。如果我在20分钟内没有睡着，我会回答这个问题。