How to Pass an Array List of Objects via Intent in Android?

How can I efficiently pass an ArrayList of objects between activities using Intent in Android?

// Passing object
Intent intent = new Intent(CurrentActivity.this, SecondActivity.class);
intent.putParcelableArrayListExtra("objectList", myObjectList);
startActivity(intent);

In Android, passing an ArrayList of objects between activities is a common requirement. This can be achieved seamlessly using Intents, especially when the objects are Parcelable or Serializable, allowing them to be transferred efficiently across the activity lifecycle.

// Custom class implementing Parcelable
public class MyObject implements Parcelable {
    private String name;

    protected MyObject(Parcel in) {
        name = in.readString();
    }

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

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

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

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

Causes

• Not implementing Parcelable or Serializable in custom class.
• Incorrect Intent key usage when retrieving the data.
• Forgetting to put the ArrayList in the Intent before starting the new activity.

Solutions

• Ensure that your objects implement the Parcelable interface for best performance.
• Use the correct key to retrieve the data from the Intent.
• Double-check that the Intent actually contains the ArrayList before trying to retrieve it.

Mistake: Not clearly defining the key used to store the ArrayList in the Intent.

Solution: Always use a constant for Intent keys to avoid typos.

Mistake: Assuming the ArrayList is automatically populated after starting the new activity.

Solution: Retrieve the ArrayList using the correct key in the next activity's onCreate method.