[英]Java While-Loop issue
我正在尝试读取包含此内容的.txt文件
lollipops 10 0.50 5.00
dietsoda 3 1.25 3.75
chocolatebar 20 0.75 15.00
它的作用是在名称,数量,价格,总计中添加四列,并从txt文件中读取它们。 然后计算小计,营业税,然后总计。 我不确定如何计算小计,因为总和始终是最后一个值,在这种情况下,这是巧克力棒的总和。
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.Scanner;
public class CatalogTester
{
public static double SALESTAX = 0.0625;
public static void main(String[] args) throws FileNotFoundException
{
String name ="";
int quantity = 0;
double price =0;
double total = 0;
double subtotal = 0;
double tax = 0;
double total_all = 0;
File inFile = new File("Catalog.txt");
Scanner in = new Scanner(inFile);
System.out.printf("%-30s %-10s %-10s %-10s\n", "Item", "Quantity","Price", "Total");
System.out.println();
System.out.println("Expected:Item Quantity Price Total");
while(in.hasNext()){
name = in.next();
quantity = in.nextInt();
price = in.nextDouble();
total = in.nextDouble();
System.out.printf("%-30s %-10d %-10.2f %-10.2f\n", name, quantity, price, total);
}
in.close();
tax = subtotal * SALESTAX;
total_all = subtotal+tax;
System.out.println("Expected:lollipops 10 0.50 5.00");
System.out.printf("%-52s %-10.2f\n", "SubTotal", subtotal);
System.out.println("Expected:SubTotal 23.75");
System.out.printf("%-52s %-10.2f\n", SALESTAX * 100 + "% Sales Tax",tax);
System.out.println("Expected:6.25% Sales Tax 1.48");
System.out.printf("%-52s %-10.2f\n", "Total", total_all);
System.out.println("Expected:Total 25.23");
}
}
您永远不会重新分配line
。 因此,每次都检查同一行。
String line = in.nextLine();
while(in.hasNextLine()){
int i = 0;
while(!Character.isDigit(line.charAt(i))) {i++;} //<--- same line
要解决此问题:
String line = in.nextLine();
while(in.hasNextLine()){
int i = 0;
while(!Character.isDigit(line.charAt(i))) {i++;}
//code
line = in.nextLine(); //added
}
您不会在while
循环中读取任何行...
您可能错过了说:
line = in.nextLine();
在循环的尽头。
在while条件下移动线路分配。
String line = in.nextLine();
while(in.hasNextLine()){
改成
while(in.hasNextLine()){
String line = in.nextLine();
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