What is serialization?

Serialization is the process of converting an object or data structure into a format that can be easily stored (for example, in a file, memory, database) or transmitted over a network. Deserialization is the reverse process.

In Android, serialization is often used for:

• Transferring data between Activities or Fragments using Intent or Bundle.
• Saving the state of Views (for example, during screen rotation).
• Caching data.
• Exchanging data with remote servers (JSON, XML).

Main serialization mechanisms in Android:

• Serializable: Easy to use, but slow and creates many temporary objects. It is part of standard Java.
• Parcelable: A faster and more efficient mechanism, specific to Android. Requires more boilerplate code for implementation.

// Parcelable example
class MyData implements Parcelable {
    private int value;
    private String text;

    // Constructor
    public MyData(int value, String text) {
        this.value = value;
        this.text = text;
    }

    // Parcelable implementation
    protected MyData(Parcel in) {
        value = in.readInt();
        text = in.readString();
    }

    public static final Creator<MyData> CREATOR = new Creator<MyData>() {
        @Override
        public MyData createFromParcel(Parcel in) {
            return new MyData(in);
        }

        @Override
        public MyData[] newArray(int size) {
            return new MyData[size];
        }
    };

    @Override
    public int describeContents() {
        return 0;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeInt(value);
        dest.writeString(text);
    }
}