除非你打算用它做一些有用的事情，否则永远不要捕获异常。
我让它工作。这是相当直截了当的。
Enter path to save your file : myfile.bin
Enter Employee ID : 99
Enter Employee Name : Rick Hightower
Enter Employee Salary : 99
Add more records [true/false]? true
Enter Employee ID : 77
Enter Employee Name : Dippy Do
Enter Employee Salary : 88
Add more records [true/false]? false
这是我所拥有的：...
public static class Employee implements Serializable {
int id;
String name;
int salary;
public Employee(int id, String name, int salary) {
this.id = id;
this.name = name;
this.salary = salary;
}
}
static Employee getData() throws IOException {
BufferedReader rdr = new BufferedReader(
new InputStreamReader(
new DataInputStream(System.in)
));
System.out.printf("Enter Employee ID : ");
int tmpid = Integer.parseInt(rdr.readLine());
System.out.printf("Enter Employee Name : ");
String tmpname = rdr.readLine();
System.out.printf("Enter Employee Salary : ");
int tmpsalary = Integer.parseInt(rdr.readLine());
//rdr.close(); this is why... you broke it :)
return new Employee(tmpid, tmpname, tmpsalary);
}
public static void main(String []args) throws Exception {
boolean moreRecords = true;
String path = null;
Scanner scanner = new Scanner(System.in);
File file = null;
System.out.printf("Enter path to save your file : ");
path = scanner.next();
file = new File(path);
while (moreRecords) {
Employee rec = Main.getData();
ObjectOutputStream dos = new ObjectOutputStream(new FileOutputStream(file));
dos.writeObject(rec);
dos.close();
System.out.printf("Add more records [true/false]? ");
moreRecords = scanner.nextBoolean();
}
它主要是您的代码，其中一些部分被删除了。
您遇到的最大问题是您正在关闭输入流。
static Employee getData() throws IOException {
BufferedReader rdr = new BufferedReader(
new InputStreamReader(
new DataInputStream(System.in)
));
System.out.printf("Enter Employee ID : ");
int tmpid = Integer.parseInt(rdr.readLine());
System.out.printf("Enter Employee Name : ");
String tmpname = rdr.readLine();
System.out.printf("Enter Employee Salary : ");
int tmpsalary = Integer.parseInt(rdr.readLine());
//rdr.close(); this is why... you broke it :) <-------------------SEE
return new Employee(tmpid, tmpname, tmpsalary);
}
Java I/O 流使用装饰器模式，因此它只是将关闭调用委托给内部流。
这解决了这个问题。你的代码有很多问题。
如果您使用的是 JDK 1.7 或更高版本，它将为您关闭该文件。
while (moreRecords) {
Employee rec = Main.getData();
try ( ObjectOutputStream dos =
new ObjectOutputStream(
new FileOutputStream(file) ) ) {
dos.writeObject(rec);
}
System.out.printf("Add more records [true/false]? ");
moreRecords = scanner.nextBoolean();
}
如果您使用的是 JDK 1.6 或 JDK 1.5：
while (moreRecords) {
Employee rec = Main.getData();
ObjectOutputStream dos = null;
try {
dos = new ObjectOutputStream(
new FileOutputStream(file) );
dos.writeObject(rec);
} finally {
if ( dos!=null ) {
dos.close();
}
}
System.out.printf("Add more records [true/false]? ");
moreRecords = scanner.nextBoolean();
}
此外，您的程序应该对用户输入进行更多验证。扫描仪可以这样做：
public static class Employee implements Serializable {
private int id;
private String name;
private BigDecimal salary;
public Employee(int id, String name, BigDecimal salary) {
this.id = id;
this.name = name;
this.salary = salary;
}
}
static Employee getData(Scanner scanner) throws IOException {
System.out.printf("Enter Employee ID : ");
while ( !scanner.hasNextInt() ) {
System.out.println("Employee IDs are numbers only");
scanner.next();
}
int employeeId = scanner.nextInt();
System.out.printf("Enter Employee Name : ");
String name = scanner.next();
System.out.printf("Enter Employee Salary : ");
while ( !scanner.hasNextBigDecimal() ) {
System.out.println("Employee salaries are decimals " +
"not random gak");
scanner.next();
}
BigDecimal salary = scanner.nextBigDecimal();
return new Employee(employeeId, name, salary);
}
public static void main(String []args) throws Exception {
boolean moreRecords = true;
String path = null;
Scanner scanner = new Scanner(System.in);
File file = null;
System.out.printf("Enter path to save your file : ");
path = scanner.next();
file = new File(path);
while (moreRecords) {
Employee rec = Main.getData(scanner);
try ( ObjectOutputStream dos =
new ObjectOutputStream(
new FileOutputStream(file) ) ) {
dos.writeObject(rec);
}
System.out.printf("Add more records [true/false]? ");
moreRecords = scanner.nextBoolean();
现在输入/输出更像这样：
Enter path to save your file : asdfasdf
Enter Employee ID : 9a
Employee IDs are numbers only
99
Enter Employee Name : Rick
Enter Employee Salary : aa
Employee salaries are decimals not random gak
99.99
Add more records [true/false]? false
扫描仪强制最终用户输入正确类型的数据。您可以将它与正则表达式结合起来以匹配名称等的模式。
我扩展了示例并添加了对扫描仪的一些讨论。
http://rick-hightower.blogspot.com/2013/10/java-scanner-example.html