how to properly implement Parcelable with an ArrayList<Parcelable>?

Question

I am having trouble making my class Parcelable. The trouble is, I am trying to write to the parcel a member in the class which is an ArrayList<Parcelable> object. The ArrayList is Serializable, and the objects (ZigBeeDev) in the list are Parcelable.

Here is the relevant code:

package com.gnychis.coexisyst;  import java.util.ArrayList; import java.util.Iterator;  import android.os.Parcel; import android.os.Parcelable;  public class ZigBeeNetwork implements Parcelable {      public String _mac;             // the source address (of the coordinator?)     public String _pan;             // the network address     public int _band;               // the channel     ArrayList<Integer> _lqis;       // link quality indicators (to all devices?)     ArrayList<ZigBeeDev> _devices;  // the devices in the network      public void writeToParcel(Parcel out, int flags) {         out.writeString(_mac);         out.writeString(_pan);         out.writeInt(_band);         out.writeSerializable(_lqis);         out.writeParcelable(_devices, 0);  // help here     }      private ZigBeeNetwork(Parcel in) {         _mac = in.readString();         _pan = in.readString();         _band = in.readInt();         _lqis = (ArrayList<Integer>) in.readSerializable();         _devices = in.readParcelable(ZigBeeDev.class.getClassLoader());  // help here     }      public int describeContents() {         return this.hashCode();     }      public static final Parcelable.Creator<ZigBeeNetwork> CREATOR =              new Parcelable.Creator<ZigBeeNetwork>() {         public ZigBeeNetwork createFromParcel(Parcel in) {             return new ZigBeeNetwork(in);         }          public ZigBeeNetwork[] newArray(int size) {             return new ZigBeeNetwork[size];         }     };      //... } 

I have marked two spots "// help here" to understand how to properly write to the parcel and how to reconstruct it. If ZigBeeDev is Parcelable (properly tested), how do I do this properly?

Answer 1

You almost got it !

You just need to do :

public void writeToParcel(Parcel out, int flags) {     out.writeString(_mac);     out.writeString(_pan);     out.writeInt(_band);     out.writeSerializable(_lqis);     out.writeTypedList(_devices); }  private ZigBeeNetwork(Parcel in) {     _mac = in.readString();     _pan = in.readString();     _band = in.readInt();     _lqis = (ArrayList<Integer>) in.readSerializable();     in.readTypedList(_devices, ZigBeeDev.CREATOR); } 

That's all!

For your list of Integer, you can also do :

out.writeList(_lqis); _lqis = new ArrayList<>(); in.readList(_lqis Integer.class.getClassLoader()); 

It should work.

Answer 2

In my case in.readTypedList(_devices, ZigBeeDev.CREATOR); gave me a NullPointerException on _devices. So I used this:

_devices = in.createTypedArrayList(ZigBeeDev.CREATOR);