我遇到了问题，我想将带有Java的ArrayList序列化到文件中。
然后我想将其反序列化为新的ArrayList并继续添加到ArrayList。
当我反序列化时，它不会加载到ArrayList，它只是打印文件内容。这是我的代码：
这是arraylist类
public class Customers implements Serializable{
ArrayList<Customer> customers = new ArrayList();
ArrayList<Customer> customers2 = new ArrayList();
public void add(Customer customerIn) {
customers.add(customerIn);
}
public void remove(Customer customerIn) {
customers.remove(customerIn);
}
public Customer findByName(String firstName, String address) {
//För varje Customer i customers
for (Customer customer : customers) {
if (firstName.equals(customer.getName())) {
if (address.equals(customer.getAddress())) {
return customer;
}
}
}
return null;
}
class for seriallize and deserialize
public class file {
public void saveObjectsToFile(Customers customers) {
try{
FileOutputStream fos= new FileOutputStream("a.listFile");
ObjectOutputStream oos= new ObjectOutputStream(fos);
oos.writeObject(customers);
oos.close();
fos.close();
}catch(IOException ioe){
ioe.printStackTrace();
}
}
public void takeOutObjectFromFile(Customers customers) {
try
{
FileInputStream fis = new FileInputStream("a.listFile");
ObjectInputStream ois = new ObjectInputStream(fis);
customers = (Customers) ois.readObject();
ois.close();
fis.close();
//
System.out.println(customers);
}catch(IOException ioe){
ioe.printStackTrace();
return;
}catch(ClassNotFoundException c){
System.out.println("Class not found");
c.printStackTrace();
return;
}
}
class for customer
//klass customer startar här.
public class Customer implements Serializable{
//Variabler int och String för kund id, namn, adress och telefon.
int CustomerID;
String customerName, customerAddress, customerPhone, Order;
//Konstruktor för klassen
public Customer(String Name, String Address, String Phone, String Order) {
this.customerName = Name;
this.customerAddress = Address;
this.customerPhone = Phone;
this.CustomerID = 100001;
this.Order = Order;
}
//Hämtar och sätter personuppgifter.
public String getName() { return this.customerName; }
public String getAddress() { return this.customerAddress; }
public String getPhone() { return this.customerPhone; }
public int getID() { return this.CustomerID; }
public String getOrder() { return this.Order; }
//Skriver ut kontroll av personuppgifter.
public void printPerson() {
System.out.println("\n\nKONTROLL AV UPPGIFTER\n");
System.out.println("Namn:\t\t\t" + getName());
System.out.println("Adress:\t\t\t" + getAddress());
System.out.println("Telefonnummer:\t\t" + getPhone());
System.out.println("KundID:\t\t\t" + getID());
System.out.println("Order:\t\t\t" + getOrder());
}
public String toString() {
return getName() + " " + getAddress() + " " + getPhone();
}
}
答案 0 :(得分：0)
问题出在这个方法上：
public void takeOutObjectFromFile(Customers customers) {
...
customers = (Customers) ois.readObject();
...
}
你只是覆盖了一个局部变量。你应该拥有的是：
public Customers takeOutObjectFromFile() {
...
return (Customers) ois.readObject();
...
}
（也可以使用try-with-resource确保在所有情况下都关闭了文件。）
答案 1 :(得分：0)
我解决了我的问题！ 现在我可以编辑我的客户了！感谢所有的帮助和建议。
public class file {
// Get all persons in file
public List<Customers> getAllPersons(String fileLocation) {
List<Customers> localPersons = new ArrayList<>();
try {
File f = new File(fileLocation);
FileInputStream fis = new FileInputStream(f);
ObjectInputStream ois = new ObjectInputStream(fis);
try {
while (true) {
localPersons.add((Customers) ois.readObject());
}
} catch (EOFException e) {
}
} catch (IOException iOException) {
} catch (ClassNotFoundException classNotFoundException) {
}
return localPersons;
}
// Get person on personId in file
public Customers getPersonOnPersonId(String fileLocation, int personId) {
Customers localPerson = null;
try {
File f = new File(fileLocation);
FileInputStream fis = new FileInputStream(f);
ObjectInputStream ois = new ObjectInputStream(fis);
try {
while (true) {
Customers tempPerson = (Customers) ois.readObject();
if(personId == tempPerson.getPersonId()) {
localPerson = tempPerson;
break;
}
}
} catch (EOFException e) {
}
} catch (IOException iOException) {
} catch (ClassNotFoundException classNotFoundException) {
}
return localPerson;
}
// Get persons on firstname in file
public List<Customers> getPersonsOnFirstName(String fileLocation, String firstName) {
List<Customers> localPersons = new ArrayList<>();
try {
File f = new File(fileLocation);
FileInputStream fis = new FileInputStream(f);
ObjectInputStream ois = new ObjectInputStream(fis);
try {
while (true) {
Customers tempPerson = (Customers) ois.readObject();
if(firstName.equals(tempPerson.getFirstName())) {
localPersons.add(tempPerson);
}
}
} catch (EOFException e) {
}
} catch (IOException iOException) {
} catch (ClassNotFoundException classNotFoundException) {
}
return localPersons;
}
// Get persons on lastname in file
public List<Customers> getPersonsOnLastName(String fileLocation, String lastName) {
List<Customers> localPersons = new ArrayList<>();
try {
File f = new File(fileLocation);
FileInputStream fis = new FileInputStream(f);
ObjectInputStream ois = new ObjectInputStream(fis);
try {
while (true) {
Customers tempPerson = (Customers) ois.readObject();
if(lastName.equals(tempPerson.getLastName())) {
localPersons.add(tempPerson);
}
}
} catch (EOFException e) {
}
} catch (IOException iOException) {
} catch (ClassNotFoundException classNotFoundException) {
}
return localPersons;
}
// Insert person in file
public void insertPerson(String fileLocation, Customers person) {
List<Customers> localPersons = new ArrayList<>();
// Select block ************************************************
int maxPersonId = 0;
try {
File f = new File(fileLocation);
FileInputStream fis = new FileInputStream(f);
ObjectInputStream ois = new ObjectInputStream(fis);
try {
while (true) {
Customers tempPerson = (Customers) ois.readObject();
localPersons.add(tempPerson);
if(maxPersonId < tempPerson.getPersonId()) {
maxPersonId = tempPerson.getPersonId();
}
}
} catch (EOFException e) {
}
} catch (IOException iOException) {
} catch (ClassNotFoundException classNotFoundException) {
}
// *************************************************************
// Set primary key value to the person block *******************
if(localPersons.isEmpty()) {
person.setPersonId(1);
} else {
maxPersonId++;
person.setPersonId(maxPersonId);
}
// *************************************************************
// Insert block ************************************************
try {
File f = new File(fileLocation);
FileOutputStream fos = new FileOutputStream(f);
ObjectOutputStream oos = new ObjectOutputStream(fos);
FileInputStream fis = new FileInputStream(f);
ObjectInputStream ois = new ObjectInputStream(fis);
localPersons.add(person);
for(Customers p : localPersons) {
oos.writeObject(p);
}
} catch (FileNotFoundException fileNotFoundException) {
System.out.println(fileNotFoundException.getMessage());
} catch (IOException ioexception) {
System.out.println(ioexception.getMessage());
}
// *************************************************************
}
// Update person in file
public void updatePerson(String fileLocation, Customers person) {
List<Customers> localPersons = new ArrayList<>();
// Select block ************************************************
try {
File f = new File(fileLocation);
FileInputStream fis = new FileInputStream(f);
ObjectInputStream ois = new ObjectInputStream(fis);
try {
while (true) {
Customers tempPerson = (Customers) ois.readObject();
if(person.getPersonId() != tempPerson.getPersonId()) {
localPersons.add(tempPerson);
} else {
localPersons.add(person);
}
}
} catch (EOFException e) {
}
} catch (IOException iOException) {
} catch (ClassNotFoundException classNotFoundException) {
}
// *************************************************************
// Insert block ************************************************
try {
File f = new File(fileLocation);
FileOutputStream fos = new FileOutputStream(f);
ObjectOutputStream oos = new ObjectOutputStream(fos);
FileInputStream fis = new FileInputStream(f);
ObjectInputStream ois = new ObjectInputStream(fis);
for(Customers p : localPersons) {
oos.writeObject(p);
}
} catch (FileNotFoundException fileNotFoundException) {
System.out.println(fileNotFoundException.getMessage());
} catch (IOException ioexception) {
System.out.println(ioexception.getMessage());
}
// *************************************************************
}
// Delete person in file
public void deletePerson(String fileLocation, int personId) {
List<Customers> localPersons = new ArrayList<>();
// Select block ************************************************
try {
File f = new File(fileLocation);
FileInputStream fis = new FileInputStream(f);
ObjectInputStream ois = new ObjectInputStream(fis);
try {
while (true) {
Customers tempPerson = (Customers) ois.readObject();
if(personId != tempPerson.getPersonId()) {
localPersons.add(tempPerson);
}
}
} catch (EOFException e) {
}
} catch (IOException iOException) {
} catch (ClassNotFoundException classNotFoundException) {
}
// *************************************************************
// Insert block ************************************************
try {
File f = new File(fileLocation);
FileOutputStream fos = new FileOutputStream(f);
ObjectOutputStream oos = new ObjectOutputStream(fos);
FileInputStream fis = new FileInputStream(f);
ObjectInputStream ois = new ObjectInputStream(fis);
for(Customers p : localPersons) {
oos.writeObject(p);
}
} catch (FileNotFoundException fileNotFoundException) {
System.out.println(fileNotFoundException.getMessage());
} catch (IOException ioexception) {
System.out.println(ioexception.getMessage());
}
// *************************************************************
}
}
答案 2 :(得分：-1)
这是因为您的arralylist正在重新初始化 将它改为私人静态决赛，这将使你的一天
private static final ArrayList<Customer> customers = new ArrayList();