com.codename1.io.Externalizable Maven / Gradle / Ivy
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package com.codename1.io;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
/**
* {@code Externalizable} is similar to the Java SE {@code Externalizable} interface this interface.
* Notice that due to the lack of reflection and use of obfuscation these objects must be registered with the
* Util class.
* Also notice that all externalizable objects must have a default public constructor.
*
* Built-In Object types
*
* The externalization process supports serializing these types and considers them to be {@code Externalizable}.
* E.g. you can just write {@code Storage.getInstance().writeObject(new Object[] {"Str1", "Str2"});} and it will work
* as expected.
* Notice that while these objects can be written, the process doesn't guarantee they will be read with the same
* object type. E.g. if you write a {@link java.util.LinkedList} you could get back a {@link java.util.ArrayList} as both
* implement {@link java.util.Collection}:
* {@link java.lang.String}, {@link java.util.Collection}, {@link java.util.Map}, {@link java.util.ArrayList},
* {@link java.util.HashMap}, {@link java.util.Vector}, {@link java.util.Hashtable}, {@link java.lang.Integer},
* {@link java.lang.Double}, {@link java.lang.Float}, {@link java.lang.Byte}, {@link java.lang.Short},
* {@link java.lang.Long}, {@link java.lang.Character}, {@link java.lang.Boolean}, {@code Object[]},
* {@code byte[]}, {@code int[]}, {@code float[]}, {@code long[]}, {@code double[]}.
*
*
*
* The sample below demonstrates the usage and registration of the {@code Externalizable} interface:
*
*
*
* WARNING: The externalization process caches objects so the app will seem to work and only fail on restart!
*
* @see Object Persistence in Codename One
* @author Shai Almog
*/
public interface Externalizable {
/**
* Returns the version for the current persistance code, the version will be
* pased to internalized thus allowing the internalize method to recognize
* classes persisted in older revisions
*
* @return version number for the persistant code
*/
public int getVersion();
/**
* Allows us to store an object state, this method must be implemented
* in order to save the state of an object
*
* @param out the stream into which the object must be serialized
* @throws java.io.IOException the method may throw an exception
*/
public void externalize(DataOutputStream out) throws IOException;
/**
* Loads the object from the input stream and allows deserialization
*
* @param version the version the class returned during the externalization processs
* @param in the input stream used to load the class
* @throws java.io.IOException the method may throw an exception
*/
public void internalize(int version, DataInputStream in) throws IOException;
/**
* The object id must be unique, it is used to identify the object when loaded
* even when it is obfuscated.
*
* @return a unique id
*/
public String getObjectId();
}