线程“主”中的异常java.lang.IllegalStateException：扫描程序在文件I / O上关闭

问题描述

我当前正在创建一个类，该类允许用户根据用户输入的ID编辑行。但是，我遇到以下错误：

线程“ main”中的异常java.lang.IllegalStateException：扫描仪已关闭”。

即使我在scanner.close()下方放置了int phone input。 有什么解释为什么会发生

package com.company;

import javax.sound.midi.SysexMessage;
import java.io.*;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Scanner;

public class Edit {
    static Scanner x;

    public static void editRecord() throws ParseException {
        Scanner scanner = new Scanner(system.in);
        System.out.println("ENter your ID");
        String ID = scanner.nextLine();
        System.out.println("ENter your new name");
        String name = scanner.nextLine();
        System.out.println("ENter your new EMail");
        String email = scanner.nextLine();
        System.out.println("ENter your new Address");
        String address = scanner.nextLine();
        System.out.println("ENter your new Date");
        String date = scanner.nextLine();
        SimpleDateFormat format = new SimpleDateFormat("dd-MM-yyyy");
        Date userDate = format.parse(date);
        System.out.println("ENter your Gender");
        String gender = scanner.nextLine();
        boolean Gender = Boolean.parseBoolean(gender);
        System.out.println("ENter your new phone number");
        int phone = scanner.nextInt();


        String filepath = "leads.csv";
    String tempfile = "temp.csv";
    File oldFile = new File(filepath);
    File newFile = new File(tempfile);
    String ID1 = ""; String name1 = "";String email1="";String address1 = ""; String userdate1 = "";
    String Gender1 = ""; String phone1 = "";
    scanner.close();
    try{
        FileWriter fw = new FileWriter(tempfile,true);
        BufferedWriter bw = new BufferedWriter(fw);
        PrintWriter pw = new PrintWriter(bw);
        x = new Scanner(new File(filepath));
        x.useDelimiter("[,\n]");

        while (x.hasNext()){
            ID1 = x.next();
            name1 = x.next();
            phone1 = x.next();
            email1 = x.next();
            address1 = x.next();
            userdate1 = x.next();
            Gender1 = x.next();
            if(ID1.equals(ID)){
                pw.println(name+","+phone+","+email+","+address+","+userDate+","+Gender);
            }
            else {
                pw.println(name1+","+phone1+","+email1+","+address1+","+userdate1+","+Gender1);
            }
            x.close();
            pw.flush();
            pw.close();
            oldFile.delete();
            File dump = new File(filepath);
            newFile.renameto(dump);
        }


    } catch (IOException e) {
        e.printstacktrace();
        System.out.println("Error Occured");
    }


    }
}

解决方法

通过 System.in 初始化的 Scanner 可以读取用户输入。 从在 try块中初始化的扫描程序抛出 IllegalStateException 。

在while循环中关闭扫描仪时会引发异常。 为避免这种情况，将 x.close（）和 pw.close（）语句移至 finally块，如下所示，

PrintWriter pw = null;
try {
    FileWriter fw = new FileWriter(tempfile,true);
    BufferedWriter bw = new BufferedWriter(fw);
    pw = new PrintWriter(bw);
    x = new Scanner(new File(filepath));
    x.useDelimiter("[,\n]");

    while (x.hasNext()){
        ...
        pw.flush();
    }

} catch (IOException e) {
    e.printStackTrace();
    System.out.println("Error Occured");
} finally {
    x.close();
    if (pw != null) {
        pw.close();
    }  
}