java - 使用扫描仪读取文本文件结果为 'InputMismatchException'

Question

这个问题已经有答案了:

Scanner is skipping nextLine() after using next() or nextFoo()? (25 个回答)

已关闭 7 年前。

我有文本文件，每一行都有人的日期(姓名、性别、年龄、体重)

David Smith
Male
32
85.83
Sarah Apple
Female
27
56.23
Teller Saimone
Male
29
87.71

这是我的代码:

Scanner inputFile = new Scanner(myFile);
while (inputFile.hasNext()) {
    Persone Pers = new Persone();
    Pers.setVehicleMake(inputFile.nextLine());
    System.out.println(Pers.getVehicleMake());
    Pers.setVehicleModel(inputFile.nextLine());
    System.out.println(Pers.getVehicleModel());
    Pers.setNumberCylinders(inputFile.nextInt());
    System.out.println(Pers.getNumberCylinders());
    Pers.setEstMPG(inputFile.nextDouble());
    System.out.println(Pers.getEstMPG());
    auotList.add(Pers);
}

当我运行代码时，出现此错误:

run:
David Smith
Male
32
85.83

Sarah Apple
Exception in thread "main" java.util.InputMismatchException
    at java.util.Scanner.throwFor(Scanner.java:864)
    at java.util.Scanner.next(Scanner.java:1485)
    at java.util.Scanner.nextInt(Scanner.java:2117)
    at java.util.Scanner.nextInt(Scanner.java:2076)
    at PersonDrive.main(PersonDrive.java:36)
/home/jaguar/.cache/netbeans/8.1/executor-snippets/run.xml:53: Java returned: 1
BUILD FAILED (total time: 1 second)

似乎当它执行下一次读取的循环时，它读取了空格

Answer 1

将 parseInt() 和 parseDouble() 方法与 nextLine() 方法结合使用将解决您的问题。我写了一些代码:

public class Person{
    private String name;
    private String gender;
    private int age;
    private double weight;

    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getGender() {
        return gender;
    }
    public void setGender(String gender) {
        this.gender = gender;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public double getWeight() {
        return weight;
    }
    public void setWeight(double weight) {
        this.weight = weight;
    }

}

和

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

public class PersonTest {   
    public static void main(String[] args) throws FileNotFoundException {
        File inputFile = new File("data.txt");
        Scanner sc = new Scanner(inputFile);

        ArrayList<Person> peopleList = new ArrayList<Person>();
        Person p;

        while (sc.hasNext()){
            p = new Person();
            p.setName(sc.nextLine());
            System.out.println(p.getName());
            p.setGender(sc.nextLine());
            System.out.println(p.getGender());
            p.setAge(Integer.parseInt(sc.nextLine()));
            System.out.println(p.getAge());
            p.setWeight(Double.parseDouble(sc.nextLine()));
            System.out.println(p.getWeight());
            peopleList.add(p);
        }

        sc.close();
    }
}

我认为您的代码不起作用的问题是，在 nextDouble() 找到 85.83 后，扫描仪跳过了该数字，仍然位于第 4 行。当您在第二个循环中调用 nextLine() 时，它返回第四行的其余部分，该行是空白的。使用我的解决方案，您可以获取整行，然后轻松地将其转换为整数或 double 。