Java新手，我正在学习InputStream类，并确实尝试实现我在Cay S. Horstmann的Core Java Volume II，第十版中找到的代码。该代码应该显示通过将数组中的数据保存和读取到文件中来读取字节序列时Input / OutputStream类如何有用。它以声明具有给定的字符串和整数的数组开始，将该数组的元素保存在.dat文件中，从.dat文件中读取元素，并将其显示在控制台中。
但是我在控制台中得到了：
Exception in thread "main" java.time.format.DateTimeParseException: Text '0' could not be parsed at index 0
at java.time.format.DateTimeFormatter.parseResolved0(DateTimeFormatter.java:1949)
at java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1851)
at java.time.LocalDate.parse(LocalDate.java:400)
at java.time.LocalDate.parse(LocalDate.java:385)
at chapter2.TextFileTest.readEmployee(TextFileTest.java:100)
at chapter2.TextFileTest.readData(TextFileTest.java:76)
at chapter2.TextFileTest.main(TextFileTest.java:35)
C:\Users\barcejo1\AppData\Local\NetBeans\Cache\8.2\executor-snippets \run.xml:53: Java returned: 1
BUILD FAILED (total time: 21 seconds)
似乎存在问题，分别将每行的int数解析为将写入.dat文件的变量。我复制了这段代码，但我不明白为什么它不起作用。我希望得到苛刻的答案，没关系。我很高兴受到教育。
import java.io.*;
import java.time.*;
import java.util.*;
/*** @version 1.14 2016-07-11
* @author Cay Horstmann
*/
public class TextFileTest
{
public static void main(String[] args) throws IOException
{
Employee[] staff = new Employee[3];
staff[0] = new Employee("Carl Cracker", 75000, 1987, 12, 15);
staff[1] = new Employee("Harry Hacker", 50000, 1989, 10, 1);
staff[2] = new Employee("Tony Tester", 40000, 1990, 3, 15);
// save all employee records to the file employee.dat
try (PrintWriter out = new PrintWriter("employee.dat", "UTF-8"))
{
writeData(staff, out);
}
// retrieve all records into a new array
try (Scanner in = new Scanner(new FileInputStream("employee.dat"), "UTF-8"))
{
Employee[] newStaff = readData(in);
// print the newly read employee records
for (Employee e : newStaff)
System.out.println(e);
}
}
//Writes all employees in an array to a print writer
private static void writeData(Employee[] employees, PrintWriter out) throws IOException
{
// write number of employees
out.println(employees.length);
for (Employee e : employees)
writeEmployee(out, e);
}
/**
* Reads an array of employees from a scanner
* @param in the scanner
* @return the array of employees
*/
private static Employee[] readData(Scanner in)
{
// retrieve the array size
int n = in.nextInt();
in.nextLine(); // consume newline
Employee[] employees = new Employee[n];
for (int i = 0; i < n; i++)
{
employees[i] = readEmployee(in);
}
return employees;
}
/**
* Writes employee data to a print writer
* @param out the print writer
*/
public static void writeEmployee(PrintWriter out, Employee e)
{
out.println(e.getName() + "|" + e.getSalary() + "|" + e.getHireDay());
}
/**
* Reads employee data from a buffered reader
* @param in the scanner
*/
public static Employee readEmployee(Scanner in)
{
String line = in.nextLine();
String[] tokens = line.split("\\|");
String name = tokens[0];
double salary = Double.parseDouble(tokens[1]);
LocalDate hireDate = LocalDate.parse(tokens[2]);
int year = hireDate.getYear();
int month = hireDate.getMonthValue();
int day = hireDate.getDayOfMonth();
return new Employee(name, salary, year, month, day);
}
}
您的代码不起作用，因为您只是在写文件。下面是固定代码：
package com.example.demo;
import java.io.*;
import java.time.*;
import java.util.*;
/***
* @version 1.14 2016-07-11
* @author Cay Horstmann
*/
public class TextFileTest {
public static void main(String[] args) throws IOException {
Employee[] staff = new Employee[3];
staff[0] = new Employee("Carl Cracker", 75000, 1987, 12, 15);
staff[1] = new Employee("Harry Hacker", 50000, 1989, 10, 1);
staff[2] = new Employee("Tony Tester", 40000, 1990, 3, 15);
// save all employee records to the file employee.dat
try (PrintWriter out = new PrintWriter("employee.dat", "UTF-8")) {
writeData(staff, out);
}
// retrieve all records into a new array
try (Scanner in = new Scanner(new FileInputStream("employee.dat"), "UTF-8")) {
Employee[] newStaff = readData(in);
// print the newly read employee records
for (Employee e : newStaff)
System.out.println(e);
}
}
//Writes all employees in an array to a print writer
private static void writeData(Employee[] employees, PrintWriter out) throws IOException {
// write number of employees
out.println(employees.length);
for (Employee e : employees)
writeEmployee(out, e);
}
/**
* Reads an array of employees from a scanner
*
* @param in the scanner
* @return the array of employees
*/
private static Employee[] readData(Scanner in) {
// retrieve the array size
int n = in.nextInt();
in.nextLine(); // consume newline
Employee[] employees = new Employee[n];
for (int i = 0; i < n; i++) {
employees[i] = readEmployee(in);
}
return employees;
}
/**
* Writes employee data to a print writer
*
* @param out the print writer
*/
public static void writeEmployee(PrintWriter out, Employee e) {
//System.out.println(LocalDate.of(e.getYear(), e.getMonth(), e.getHireDay()).toString());
out.println(e.getName() + "|" + e.getSalary() + "|" + LocalDate.of(e.getYear(), e.getMonth(), e.getHireDay()).toString());
}
/**
* Reads employee data from a buffered reader
*
* @param in the scanner
*/
public static Employee readEmployee(Scanner in) {
String line = in.nextLine();
String[] tokens = line.split("\\|");
String name = tokens[0];
double salary = Double.parseDouble(tokens[1]);
LocalDate hireDate = LocalDate.parse(tokens[2]);
int year = hireDate.getYear();
int month = hireDate.getMonthValue();
int day = hireDate.getDayOfMonth();
return new Employee(name, salary, year, month, day);
}
}