问题
I have been successful in compiling my inventory program:
// Inventory.java part 1
// this program is to calculate the value of the inventory of the Electronics Department's cameras
import java.util.*;
import javax.swing.*;
import java.awt.event.*;
import java.io.*;
public class Inventory
{
public static void main(String[] args)
{
// create Scanner to obtain input from the command window
Scanner input = new Scanner (System.in);
String name;
int itemNumber; // first number to multiply
int itemStock; // second number to multiply
double itemPrice; //
double totalValue; // product of number1 and number2
while(true){ // infinite loop
// make new Camera object
System.out.print("Enter Department name: "); //prompt
String itemDept = input.nextLine(); // read name from user
if(itemDept.equals("stop")) // exit the loop
break;
{
System.out.print("Enter item name: "); // prompt
name = input.nextLine(); // read first number from user
input.nextLine();
}
System.out.print("Enter the item number: "); // prompt
itemNumber = input.nextInt(); // read first number from user
input.nextLine();
while( itemNumber <= -1){
System.out.print("Enter valid number:"); // prompt
itemNumber = input.nextInt(); // read first number from user input.nextLine();
} /* while statement with the condition that negative numbers are entered
user is prompted to enter a positive number */
System.out.print("Enter number of items on hand: "); // prompt
itemStock = input.nextInt(); // read first number from user
input.nextLine();
while( itemStock <= -1){
System.out.print("Enter positive number of items on hand:"); // prompt
itemStock = input.nextInt(); // read first number from user
input.nextLine();
} /* while statement with the condition that negative numbers are entered
user is prompted to enter a positive number */
System.out.print("Enter item Price: "); // prompt
itemPrice = input.nextDouble(); // read second number from user
input.nextLine();
while( itemPrice <= -1){
System.out.print("Enter positive number for item price:"); // prompt
itemPrice = input.nextDouble(); // read first number from user
input.nextLine();
} /* while statement with the condition that negative numbers are entered
user is prompted to enter a positive number */
Cam camera = new Cam(name, itemNumber, itemStock, itemPrice);
totalValue = itemStock * itemPrice; // multiply numbers
System.out.println("Department name:" + itemDept); // display Department name
System.out.println("Item number: " + camera.getItemNumber()); //display Item number
System.out.println("Product name:" + camera.getName()); // display the item
System.out.println("Quantity: " + camera.getItemStock());
System.out.println("Price per unit" + camera.getItemPrice());
System.out.printf("Total value is: $%.2f\n" + totalValue); // display product
} // end while method
} // end method main
}/* end class Inventory */
class Cam{
private String name;
private int itemNumber;
private int itemStock;
private double itemPrice;
private String deptName;
public Cam(String name, int itemNumber, int itemStock, double itemPrice) {
this.name = name;
this.itemNumber = itemNumber;
this.itemStock = itemStock;
this.itemPrice = itemPrice;
}
public String getName(){
return name;
}
public int getItemNumber(){
return itemNumber;
}
public int getItemStock(){
return itemStock;
}
public double getItemPrice(){
return itemPrice;
}
}
C:\Java>java Inventory
Enter Department name: Electronics
Enter item name: camera
Enter the item number: 12345
Enter number of items on hand: 8
Enter item Price: 100.50
Department name:Electronics
Item number: 12345
Product name:camera
Quantity: 8
Price per unit100.5
Total value is:
$Exception in thread "main" java.util.MissingFormatArgumentException:
Format specifier '.2f'
at java.util.Formatter.format(Unknown Source)
at java.io.PrintStream.format(Unknown Source)
at java.io.PrintStream.printf(Unknown Source)
at Inventory.main(Inventory.java:82)
I seem to come to this format error and cannot see why.
回答1:
If you are using printf, you need to specify the placeholders as printf parameters along with the format string. In your case you are passing a single string by appending the amount hence the error.
System.out.printf("Total value is: $%.2f\n" + totalValue)
should be replaced by
System.out.printf("Total value is: $%.2f\n", totalValue)
回答2:
This is the problem:
System.out.printf("Total value is: $%.2f\n" + totalValue);
I think you meant:
System.out.printf("Total value is: $%.2f\n", totalValue);
In other words, specify the value to replace the placeholder with, instead of just using string concatenation to add the value to the send of the format string.
In general though, when you get an exception you don't understand, you should look at the documentation for it. In this case, the docs are reasonably clear:
Unchecked exception thrown when there is a format specifier which does not have a corresponding argument or if an argument index refers to an argument that does not exist.
So there are two things you need to check in your code:
- Do you have a format specifier without a corresponding argument?
- Do you have an argument index which refers to an argument that doesn't exist?
You haven't specified any argument indexes in your format string, so it must be the first case - which indeed it is.
回答3:
System.out.printf("Total value is: $%.2f\n", totalValue); // display product
-> http://www.java2s.com/Code/JavaAPI/java.lang/Systemoutprintf2ffloatf.htm
来源：https://stackoverflow.com/questions/7625233/missingformatargumentexception-error