从文件中正确读取输入时出现问题

Question

在我当前的项目中，我必须从输入文件中读取一些数字(第一个是系数，第二个是的指数(。由于某种原因，我在使用"；Integer.parseInt"；。有人知道为什么/如何解决这个问题吗？下面的当前代码。

错误消息：

Exception in thread "main" java.lang.NumberFormatException: For input string: "2 5 "
at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:68)
at java.base/java.lang.Integer.parseInt(Integer.java:652)
at java.base/java.lang.Integer.parseInt(Integer.java:770)
at polynomialproject.Driver.main(Driver.java:35)

Java returned: 1
BUILD FAILED (total time: 0 seconds)

输入文件：

2 5 
-4 3 
1 1 
-16 0

驱动程序：

import java.io.*; //Can use all io's
import java.util.*; //Can use all util's
import polynomialproject.SortedLinkedList;
import polynomialproject.SortedListInterface;
public class Driver {

private static Scanner file;
static PrintWriter outputFilePrinter;
static Scanner inputFileScanner;
public static void main(String[] args) throws FileNotFoundException {

Scanner inFile;
PrintWriter printWriter = new PrintWriter("output.txt");  //printWriter will output to proper text
inFile = new Scanner(new File("input.txt"));

Polynomial One = new Polynomial();

while (inFile.hasNext()) {
String String1 = inFile.nextLine(); //Reads lines
int one = Integer.parseInt(String1);
String String2 = inFile.nextLine();
int two = Integer.parseInt(String2);
One.setTerm(two, one);
}

Polynomial Two = new Polynomial();

while (inFile.hasNext()){
String String1 = inFile.nextLine();
int one = Integer.parseInt(String1);
String String2 = inFile.nextLine();
int two = Integer.parseInt(String2);
One.setTerm(two, one);

}

printWriter.println(One.toString());
printWriter.println("The degree of the first polynomial is: " + One.getDegree());
printWriter.println("The coefficient of exponent two is: " + One.getCoefficient(2));
printWriter.println("The coefficient of exponent three is: " + One.getCoefficient(3));

printWriter.println("The degree of the second polynomial is: " + Two.getDegree());
printWriter.println("The sum of the polynomials is: " + Two.sum(Two));

printWriter.close();
}//End main

}//End Driver

Answer 1

您在一个while循环中跳过了两行，不要这样做。由于您一次扫描整行，所以在阅读后还需要拆分该行(空格为delim(。

while (inFile.hasNext()) {
String line = inFile.nextLine();
String[] numbers = line.split(" ");
int one = Integer.parseInt(numbers[0]);
int two = Integer.parseInt(numbers[1]);
One.setTerm(two, one);
}

此外，扫描仪就像迭代器——一旦你在while循环中使用它，它就是"迭代器"；使用"；。要再次扫描文件，您需要在两个while循环之间再次创建它：

inFile = new Scanner(new File("input.txt"));

Answer 2

nextLine()读取一行文本。因此它有这个名字。

你不想要一行文字；毕竟，1行包含2个整数。你只需要一个整数。

呼叫.nextInt()(忘记Integer.parseInt(。