What is the difference between Serializable and Parcelable in Android?

The main difference lies in performance and implementation method.

• Serializable:

  • Standard interface from Java SE.
  • Easier to implement (just implement the interface).
  • Uses Java Reflection API for serialization, which is slower and requires more memory.
  • Suitable for small objects or when serialization performance is not critical.

• Parcelable:

  • Specific interface for Android SDK.
  • Requires explicit description of the serialization/deserialization process.
  • Significantly faster and more memory-efficient as it does not rely on Reflection.
  • The best choice for passing objects between Android components (Activity, Service, BroadcastReceiver) and saving state.

To implement Parcelable, you need to:

1. Implement the Parcelable interface.
2. Implement the writeToParcel() method to write data into a Parcel.
3. Implement the describeContents() method.
4. Create a static CREATOR object that implements the Parcelable.Creator interface.

import android.os.Parcel;
import android.os.Parcelable;

public class MyParcelableObject implements Parcelable {
    private int value;
    private String name;

    public MyParcelableObject(int value, String name) {
        this.value = value;
        this.name = name;
    }

    protected MyParcelableObject(Parcel in) {
        value = in.readInt();
        name = in.readString();
    }

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

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

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

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

Comparison table:

Attribute	Serializable	Parcelable
Library	java.io	android.os
Performance	Low (uses Reflection)	High
Memory efficiency	Low	High
Implementation	Simpler	More complex
Usage	General Java, small data	Android, passing data between components