How to serialize an ObservableList

Question

I am working on a javaFx project where we should use an ObservableList to add Listners. ObservableList includes a Model of faces. But I want to save the entire ObservableList object in a file through serialization. But he gives me an exception . I also applied serialization on the object model, but no luck. Is there a way to serialize an ObservableList ?

EmployeeModel

 package com.company.Model; import javax.persistence.*; import java.io.Serializable; /** * Created by Sunny on 1/8/2016. */ @Entity @Table(name = "Employee", schema = "", catalog = "PUBLIC") public class EmployeeEntity implements Serializable { private String empId; private String empAddress; private String empNumber; private String empFirstName; private String empLastName; public EmployeeEntity(String empId, String empAddress, String empNumber, String empFirstName, String empLastName) { this.empId = empId; this.empAddress = empAddress; this.empNumber = empNumber; this.empFirstName = empFirstName; this.empLastName = empLastName; } public EmployeeEntity() { } @Id @Column(name = "emp_ID") public String getEmpId() { return empId; } public void setEmpId(String empId) { this.empId = empId; } @Basic @Column(name = "emp_address") public String getEmpAddress() { return empAddress; } public void setEmpAddress(String empAddress) { this.empAddress = empAddress; } @Basic @Column(name = "emp_number") public String getEmpNumber() { return empNumber; } public void setEmpNumber(String empNumber) { this.empNumber = empNumber; } @Basic @Column(name = "emp_firstName") public String getEmpFirstName() { return empFirstName; } public void setEmpFirstName(String empFirstName) { this.empFirstName = empFirstName; } @Basic @Column(name = "emp_lastName") public String getEmpLastName() { return empLastName; } public void setEmpLastName(String empLastName) { this.empLastName = empLastName; } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; EmployeeEntity that = (EmployeeEntity) o; if (empId != null ? !empId.equals(that.empId) : that.empId != null) return false; if (empAddress != null ? !empAddress.equals(that.empAddress) : that.empAddress != null) return false; if (empNumber != null ? !empNumber.equals(that.empNumber) : that.empNumber != null) return false; if (empFirstName != null ? !empFirstName.equals(that.empFirstName) : that.empFirstName != null) return false; if (empLastName != null ? !empLastName.equals(that.empLastName) : that.empLastName != null) return false; return true; } @Override public int hashCode() { int result = empId != null ? empId.hashCode() : 0; result = 31 * result + (empAddress != null ? empAddress.hashCode() : 0); result = 31 * result + (empNumber != null ? empNumber.hashCode() : 0); result = 31 * result + (empFirstName != null ? empFirstName.hashCode() : 0); result = 31 * result + (empLastName != null ? empLastName.hashCode() : 0); return result; } } 

Serialization

  public void write(ObservableList<EmployeeEntity> personObservalble) { try { // write object to file FileOutputStream fos = new FileOutputStream("Objectsavefile.ser"); ObjectOutputStream oos = new ObjectOutputStream(fos); oos.writeObject(personsObservable); oos.close(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } 

Exception

 java.io.NotSerializableException: com.sun.javafx.collections.ObservableListWrapper at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1184) at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348) at FileWriter.write(FileWriter.java:14) at Main.main(Main.java:12) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:497) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144) Process finished with exit code 0 

Answer 1

ObservableList Implementations are not Serializable (in fact, there is no reasonable way to define behavior for serializing listeners, and not for serializing listeners in general - this is just like serializing an unobservable list with the same data, I think this is what you want to do here.) Assuming your Person class is Serializable (and these instances can be serialized), you can do:

  public void write(ObservableList<EmployeeEntity> personObservalble) { try { // write object to file FileOutputStream fos = new FileOutputStream("Objectsavefile.ser"); ObjectOutputStream oos = new ObjectOutputStream(fos); oos.writeObject(new ArrayList<EmployeeEntity>(personsObservable)); oos.close(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } 

To read it, you must:

 ObjectInputStream ois = ... ; List<EmployeeEntity> list = (List<EmployeeEntity>) ois.readObject(); personsObservable = FXCollections.observableList(list); 

Here is the complete test. I ran this and it worked (I deleted the save annotations since I did not have javax.persistence on the classpath in the test environment, but this should not make any difference).

 import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStream; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.io.OutputStream; import java.nio.file.Files; import java.nio.file.Path; import java.util.ArrayList; import java.util.List; import javafx.collections.FXCollections; import javafx.collections.ObservableList; public class SerializeObservableListTest { public static void main(String[] args) throws IOException { EmployeeEntity bill = new EmployeeEntity("1000", "Seattle, WA", "1000", "Bill", "Gates"); EmployeeEntity tim = new EmployeeEntity("2000", "Mobile, AL", "2000", "Tim", "Cook"); ObservableList<EmployeeEntity> staff = FXCollections.observableArrayList(bill, tim); Path temp = Files.createTempFile("employees", "ser"); write(staff, temp); ObservableList<EmployeeEntity> listFromFile = read(temp); System.out.println("Lists equal? "+listFromFile.equals(staff)); } private static void write(ObservableList<EmployeeEntity> employees, Path file) { try { // write object to file OutputStream fos = Files.newOutputStream(file); ObjectOutputStream oos = new ObjectOutputStream(fos); oos.writeObject(new ArrayList<EmployeeEntity>(employees)); oos.close(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } private static ObservableList<EmployeeEntity> read(Path file) { try { InputStream in = Files.newInputStream(file); ObjectInputStream ois = new ObjectInputStream(in); List<EmployeeEntity> list = (List<EmployeeEntity>) ois.readObject() ; return FXCollections.observableList(list); } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } return FXCollections.emptyObservableList(); } }