用小数点计算变化（可能是简单的解决方案）

Question

我有以下代码（我不是很懂电脑，所以要温和），用户应该能够输入单个硬币数量，程序会告诉用户他们在所述硬币中有多少钱金额。

import java.util.*;

public class Coins {
  public static final Scanner CONSOLE = new Scanner(System.in);

  public static void main(String[] args) {

    System.out.println ("Lab 2 by Maria T Williams\n");

    quarterAmount( );
    dimeAmount( );
    nickelAmount( );
    pennyAmount( );
  }

  public static void quarterAmount( ) {
    System.out.print("Enter the number of quarters: ");
    int quarterNumber = CONSOLE.nextInt( );
    double amount = quarterNumber * 0.25;
    System.out.print(quarterNumber + " You have $" + amount);
    System.out.println(" worth of quarters.");
  }

  public static void dimeAmount( ) {
    System.out.print("Enter the number of dimes: ");
    int dimeNumber = CONSOLE.nextInt( );
    double amount = dimeNumber * .10;
    System.out.print(dimeNumber + " You have $" + amount);
    System.out.println(" worth of dimes.");
  }

  public static void nickelAmount( ) {
    System.out.print("Enter the number of nickels: ");
    int nickelNumber = CONSOLE.nextInt( );
    double amount = nickelNumber * 0.05;
    System.out.print(nickelNumber + " You have $" + amount);
    System.out.println(" worth of nickels.");
  }

  public static void pennyAmount( ) {
    System.out.print("Enter the number of pennies: ");
    int pennyNumber = CONSOLE.nextInt( );
    double amount = pennyNumber * 0.01;
    System.out.print(pennyNumber + " You have $" + amount);
    System.out.println(" worth of pennies.");
  }
}

如果我输入的金额在 100 位的数字不是“0”，我没问题。但是，如果我输入，比如说，两个季度，我会得到“$0.5”而不是“$0.50”。

Answer 1

您可以使用 DecimalFormat 来强制按照您的喜好设置数字格式。例如：

DecimalFormat df = new DecimalFormat("#.00");
double amount = dimeNumber * .10;
System.out.print(dimeNumber + " You have $" + df.format(amount) + " worth of dimes.");

Answer 2

输出计算结果时，可以这样使用DecimalFormat：

    DecimalFormat f = new DecimalFormat("#0.00");
    System.out.println(f.format(dimeNumber));

用小数点计算变化（可能是简单的解决方案）

Counting Change with decimal point (probably simple solution)

java

number-formatting