如何序列化对象的ArrayList？

Question

I want to serialize an arraylist of Item but it doesn't work....

my Item class extends Stuff class and has some subclasses .

all of my classes implement Serilalizable.

i have this part :

 try{ // Serialize data object to a file ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("MyData.ser")); out.writeObject(myData); out.close(); // Serialize data object to a byte array ByteArrayOutputStream bos = new ByteArrayOutputStream() ; out = new ObjectOutputStream(bos) ; out.writeObject(myData); out.close(); // Get the bytes of the serialized object byte[] buf = bos.toByteArray(); } catch (IOException e) { } 

my classes :

 public class Stuff implements Serializeable{ .... some protected fields . . } public class Item extends Stuff implements Serializable{ ... .. . } and some subclasses of Item: public class FirstItem extends Item implements Serializable{ ... } public class SecondItem extends Item implements Serializable{ ... } ... I want to serialize an object contains ArrayList of <Item> that has objects of Item's subclasses (FirstItem,SecondItem,...) 

i think informations are sufficient...

it's just a little mistake and now works correctly... I'm sorry for my stupid question.

Thank you for your answers.

Answer 1

You can serialize class of ArrayList like this

public class MyData implements Serializable {

    private long id;
    private String title;
    private ArrayList<String> tags;
    ...

    public String getTitle() {
    }
}

And to create serializable

    ArrayList<MyData> myData = new ArrayList<MyData>();

try{
    // Serialize data object to a file
    ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("MyData.ser"));
    out.writeObject(myData);
    out.close();

    // Serialize data object to a byte array
    ByteArrayOutputStream bos = new ByteArrayOutputStream() ;
    out = new ObjectOutputStream(bos) ;
    out.writeObject(myData);
    out.close();

    // Get the bytes of the serialized object
    byte[] buf = bos.toByteArray();
} catch (IOException e) {
}

Answer 2

I'm taking a leap here that you are trying to serialize to something like json?

if so, you can use jackson ( http://jackson.codehaus.org/ )

final ObjectMapper mapper = new ObjectMapper();
try
{
    final String jsonString = mapper.writeValueAsString( _integrationSettings );
    // do something with the string...
}
catch( IOException e )
{
    // use a logger to output error
}

You can also deserialize with jackson as well...

A more detailed example here: http://blog.inflinx.com/2012/05/10/using-jackson-for-javajson-conversion/

Note: you can do similar for XML.