使用以下代码输出到已建立的文件时:
import java.util.Scanner;
import java.io.*;
public class BarakProductOrder
{
public static void main(String[] args) throws IOException
{
//Establish scanner object
Scanner input = new Scanner (System.in);
//Declare variables
String name, product, street, city, state, zip;
int qty;
double price;
//Collect data
System.out.println("Welcome to Matt's Dog Food Emporium!\n\nWhat is your name?");
name = input.nextLine();
System.out.println("Which product would you like to order today?");
product = input.nextLine();
System.out.println("How many would you like?");
qty = input.nextInt();
price = 4.56*qty;
input.nextLine(); //Must be placed to not skip over "address" line
System.out.println("Enter your street address:");
street = input.nextLine();
System.out.println("Enter the City:");
city = input.nextLine();
System.out.println("Enter the State (ex.: NY):");
state = input.nextLine();
System.out.println("Enter the Zip:");
zip = input.nextLine();
System.out.println("Thank you for your order, " + name);
//Output data to file "BarakOrder.txt"
PrintWriter outputFile = new PrintWriter("C:\\Users\\fbara\\Desktop\\CISS 110\\BarakOrder.txt");
outputFile.println("Order Number: 001");
outputFile.println("Product: " + product);
outputFile.println("Quantity: " + qty);
outputFile.printf("Price = 4.56*" + qty + " = $" + "%.2f" + price);
outputFile.println("Customer Contact Info: " + name);
outputFile.println("Address: " + street);
outputFile.println(city + ", " + state + " " + zip);
//Close scanner and file object
input.close();
outputFile.close();
System.out.println("Data has been written.");
}
}
在第45行使用“%.2f”修饰符会给我以下错误消息:
java.util.MissingFormatArgumentException:格式说明符'%.2f'位于 java.util.Formatter.format(未知源) java.io.PrintWriter.format(未知源) java.io.PrintWriter.printf(未知源)在 BarakProductOrder.main(BarakProductOrder.java:45)在 sun.reflect.NativeMethodAccessorImpl.invoke0(本机方法)位于 sun.reflect.NativeMethodAccessorImpl.invoke(未知来源)位于 sun.reflect.DelegatingMethodAccessorImpl.invoke(未知源)位于 java.lang.reflect.Method.invoke(来源未知) edu.rice.cs.drjava.model.compiler.JavacCompiler.runCommand(JavacCompiler.java:267)
我在outputFile.printf
上使用了错误的修饰符吗?还是“ .print()”行错误?
答案 0 :(得分:1)
printf
的工作方式并非如此;你给它一个格式,然后打印的东西。
您没有传递任何要使用%.2f
进行格式化的内容,而是尝试添加它。这些文档提供了有关如何使用它的信息(世界上有很多示例)。
大致:
outputFile.printf("Price = 4.56*" + qty + " = $" + "%.2f", price);
尽管我不确定为什么您不会对qty
进行相同的格式化。