Introduction to Android Serialization and Deserialization

Serialization and deserialization are essential concepts in Android development when it comes to storing and retrieving data. These processes allow you to convert objects or data structures into formats that can be easily stored or transmitted, and then reconstructed back into their original form when needed. In this article, we will explore how serialization and deserialization work in Android, using both Kotlin and Java programming languages.

What is Serialization?

Serialization refers to the process of converting an object into a byte stream that can be easily stored, transmitted, or shared. The byte stream can be stored in files, sent across networks, or saved in databases. When an object is serialized, not only its values but also its data types and class information are preserved. This allows the object to be reconstructed later, retaining its original state.

What is Deserialization?

Deserialization, on the other hand, is the process of reconstructing an object from a byte stream. It involves reading the byte stream and reassembling the object, restoring all its data members and class information. Deserialization is the reverse process of serialization.

Benefits of Serialization and Deserialization

Serialization and deserialization provide several benefits in Android development:

1. Persistence: Serialized objects can be stored in files or databases, allowing data to persist even when the application is closed or the device is restarted.
2. Inter-process Communication: Serialized objects can be transmitted across network boundaries, shared between different processes, or sent as a message between different components of an application.
3. State Restoration: Serialized objects can be used to restore the state of an application, allowing users to resume where they left off.
4. Caching: Serialized objects can be cached, improving the performance and efficiency of an application by reducing the need for frequent data retrieval.

Serialization in Android

Android provides built-in support for serialization through the java.io.Serializable interface. By implementing this interface, you can mark your objects as serializable and use the provided methods for serialization and deserialization.

For example, suppose we have a Person class with several properties such as name, age, and address. To make this class serializable, we would simply implement the Serializable interface as follows:

import java.io.Serializable

data class Person(val name: String, val age: Int, val address: String) : Serializable {
    // Other class methods and properties
}

In this case, all the properties of the Person class will be automatically serialized. To serialize an instance of this class, we can use the ObjectOutputStream class:

val person = Person("John Doe", 30, "123 Main St")
val outputStream = ObjectOutputStream(FileOutputStream("person.ser"))
outputStream.writeObject(person)
outputStream.close()

Here, we create a Person object and write it to a file named “person.ser” using an ObjectOutputStream. The writeObject method serializes the object and writes it to the file. Finally, we close the output stream to release any system resources.

Deserialization in Android

To deserialize an object, we can use the ObjectInputStream class. It reads data from a byte stream and reconstructs the original object.

val inputStream = ObjectInputStream(FileInputStream("person.ser"))
val person = inputStream.readObject() as Person
inputStream.close()

In this example, we create an ObjectInputStream and read the serialized object from the “person.ser” file. We cast the obtained object to our Person class and assign it to the person variable.

Conclusion

Serialization and deserialization are powerful tools in Android development for storing, sharing, and transmitting data. By understanding these concepts and leveraging the built-in support provided by Android, you can effectively manipulate objects and persist data in your applications. 参考文献：

1. Mastering Data Serialization and Deserialization