Question

我正在编写一个程序，它接受一个文件并尝试使用文件中的数据来创建输出。

这是该计划：

import java.util.Scanner;
import java.io.*;


 public class WebberProjectTest
 {

 public static void main(String[] args) throws IOException 
 {

 Scanner scanner = new Scanner(new File("portlandvip.txt"));
 while (scanner.hasNext())
  {
 String firstName = scanner.next();
 String lastName = scanner.next();
 Integer number = scanner.nextInt();
 String ticketType = scanner.next();

 if(ticketType == "Court")
 {
 Integer a = 75 * number;
 System.out.println(" " + firstName + " " + lastName + " " + a);            
 scanner.nextLine();  
 }

 if(ticketType == "Box")
 {
 Integer a = 50 * number;
 System.out.println(" " + firstName + " " + lastName + " " + a);            
 scanner.nextLine();  
 }

 if(ticketType == "Club")
 {
Integer a = 40 * number;
System.out.println(" " + firstName + " " + lastName + " " + a);            
 scanner.nextLine();  
  }


}       

  }    
}

这是数据文件：

Loras Tyrell 5俱乐部

Margaery Tyrell 8 Box

Roslin Frey 2 Box

Sansa Stark 2 Club

Jon Snow 5 Club

Edmure Tully 3 Box

Joffrey Baratheon 20 Court

Stannis Baratheon 4 Club

Jaime Lannister 2 Box

Cersei Lannister 1 Court

Beric Dondarrion 8 Court

Balon Greyjoy 16 Box

Olenna Tyrell 4 Court

梅斯泰瑞尔5盒

Tyrion Lannister 2俱乐部

Sandor Clegane 2 Court

Gregor Clegane 6 Club

Samwell Tarly 3 Club

Petyr Baelish 6 Court

这个程序的目的是以输入文件和输出为例。

输入：Loras Tyrell 5 Court

输出：Loras Tyrell $ 375.00

但是，当我运行程序时，没有任何反应。我有一些想法为什么会发生这种情况，但我不知道如何解决它，任何帮助将不胜感激。

我还有关于printf语句的另一个问题。我改变了程序以便正确打印，但现在我必须将println语句更改为printf语句。这就是我改变程序的样子：

import java.util.Scanner;
import java.io.*;


public class WebberProjectTest
{

public static void main(String[] args) throws IOException 
{

Scanner scanner = new Scanner(new File("portlandvip.txt"));
while(scanner.hasNext()) 
{
String line = scanner.nextLine();
String[] words = line.split(" "); 

if(words[3].equals("Court")) 
{
    int a = 75 * Integer.parseInt(words[2]);
    System.out.printf(" " + words[0] + " " + words[1] + " $%.2f\n ", a);
}

if(words[3].equals("Box")) 
{
    int a = 50 * Integer.parseInt(words[2]);
    System.out.printf(" " + words[0] + " " + words[1] + " $%.2f\n", a);
}

if(words[3].equals("Club")) 
{
    int a = 40 * Integer.parseInt(words[2]);
    System.out.printf(" " + words[0] + " " + words[1] + " $%.2f\n", a);
}
}       


 }    
}

这就是打印出来的内容：

Loras Tyrell Loras Tyrell $java.util.IllegalFormatConversionException: f !=         java.lang.Integer
at java.util.Formatter$FormatSpecifier.failConversion(Unknown Source)
at java.util.Formatter$FormatSpecifier.printFloat(Unknown Source)
at java.util.Formatter$FormatSpecifier.print(Unknown Source)
at java.util.Formatter.format(Unknown Source)
at java.io.PrintStream.format(Unknown Source)
at java.io.PrintStream.printf(Unknown Source)
at WebberProjectTest.main(WebberProjectTest.java:32)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at edu.rice.cs.drjava.model.compiler.JavacCompiler.runCommand(JavacCompiler.java:272)

我不知道我在printf声明中做错了什么，谢谢你的帮助。

Answer 1

立即尝试阅读行，然后拆分元素..像这样的东西

while(inp.hasNext()) {
    String line = inp.nextLine();
    String[] words = line.split(" ");            
    if(words[3].equals("Court")) {
        int a = 75 * Integer.parseInt(words[2]);
        System.out.println(" " + words[0] + " " + words[1] + " " + a);
    }
    // ....other if conditions
    if(inp.hasNext())   //to skip over empty line
        inp.nextLine();
}

Answer 2

字符串应与equals()方法而不是==运算符进行比较。如，

ticketType.equals("Court") //instead of ==> ticketType == "Court"

Answer 3

试试这段代码。

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
import java.util.StringTokenizer;


public class test {

    /**
     * @param args
     */
    public static void main(String[] args) {
        try {
            Scanner scanner = new Scanner(new File("test.txt"));
            while (scanner.hasNext()){
                String string = scanner.useDelimiter("\n").next();

                if(!string.equals(" ") && !string.equals("\n") && !string.equals("") && !string.equals("\r") ){
                    StringTokenizer st = new StringTokenizer(string," ");
                    String firstName = "";
                    String lastName = "";
                    Integer number = 0;
                    String ticketType = "";
                    while (st.hasMoreElements()) {
                        firstName = st.nextElement().toString();
                        lastName = st.nextElement().toString();
                        number = Integer.parseInt(st.nextElement().toString());
                        ticketType = st.nextElement().toString().trim();
                        System.out.println(" " + firstName + " " + lastName + " " + number + " " +ticketType); 
                    }
                    if(ticketType.equalsIgnoreCase("Court"))
                    {
                        Integer a = 75 * number;
                        System.out.println(" " + firstName + " " + lastName + " " + a);  
                    }
                    else if(ticketType.equalsIgnoreCase("Box"))
                    {
                        Integer a = 50 * number;
                        System.out.println(" " + firstName + " " + lastName + " " + a);   
                    }
                    else if(ticketType.equalsIgnoreCase("Club"))
                    {
                        Integer a = 40 * number;
                        System.out.println(" " + firstName + " " + lastName + " " + a);            
                    }
                }//if(!string.equals(" "))

            }//while
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

}

有程序输出printf的麻烦

3 个答案: