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How to fix: Unable to invoke no-args constructor for class X: Registering an InstanceCreator with Gson for this type may fix this problem

I am trying to make a list of objects that are all of an abstract class, but each are there own class. This list needs to persistent so I figured I implement parcelable since I have done so in the past. Only not with different classes all of an abstract class.
I tried just making the abstract class parcelable but that can't have a creator that I am used to because (of course) you can't create an instance of it (because it is abstract). Reading around I noticed that people said you dont need a constructor in the abstract class, just in the subclasses.
AbstractFocusPower class
public abstract class AbstractFocusPower implements Parcelable {
private transient AppExtension app;
private ImplementSchool school;
private String name;
private int duration;
private int cost;
private int altCost;
private int requiredLevel;
private boolean isSelected;
private boolean isResonant;
private int nofSpirtBonusUsed;
/**
* Constructor for Focus Power with no alternative cost
*/
public AbstractFocusPower(AppExtension app, ImplementSchool school, String name, int requiredLevel, int duration, int cost, boolean isSelected) {
this.app = app;
this.school = school;
this.name = name;
this.requiredLevel = requiredLevel;
this.duration = duration;
this.cost = cost;
this.altCost = -1;
this.isSelected = isSelected;
this.isResonant = false;
}
// I cut out the other constructors
public abstract AbstractFocusPower makeCopy();
public abstract String getDescription();
// I cut out the getters and setters
#Override
public int describeContents() {
return 0;
}
#Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeInt(this.school == null ? -1 : this.school.ordinal());
dest.writeString(this.name);
dest.writeInt(this.duration);
dest.writeInt(this.cost);
dest.writeInt(this.altCost);
dest.writeInt(this.requiredLevel);
dest.writeByte(this.isSelected ? (byte) 1 : (byte) 0);
dest.writeByte(this.isResonant ? (byte) 1 : (byte) 0);
dest.writeInt(this.nofSpirtBonusUsed);
}
protected AbstractFocusPower(Parcel in) {
int tmpSchool = in.readInt();
this.school = tmpSchool == -1 ? null : ImplementSchool.values()[tmpSchool];
this.name = in.readString();
this.duration = in.readInt();
this.cost = in.readInt();
this.altCost = in.readInt();
this.requiredLevel = in.readInt();
this.isSelected = in.readByte() != 0;
this.isResonant = in.readByte() != 0;
this.nofSpirtBonusUsed = in.readInt();
}
Sample subclass
public class AegisFocusPower extends AbstractFocusPower {
public AegisFocusPower(AppExtension app) {
super(app, ImplementSchool.ABJURATION, app.getString(R.string.focus_power_name_aegis), 0, 1, 1, false);
}
#Override
public String getDescription() {
return getApp().getString(R.string.focus_power_desc_aegis, (1+((int) Math.floor(getApp().getCurrentCharacter().getOccultistLevel()/6.0))));
}
#Override
public AegisFocusPower makeCopy() {
return new AegisFocusPower(getApp());
}
public AegisFocusPower(Parcel in) {
super(in);
}
public static final Parcelable.Creator<AegisFocusPower> CREATOR = new Parcelable.Creator<AegisFocusPower>() {
public AegisFocusPower createFromParcel(Parcel in) {
return new AegisFocusPower (in);
}
public AegisFocusPower [] newArray(int size) {
return new AegisFocusPower[size];
}
};
}
Code where I use it
Gson gsonFocusPowers = new Gson();
String jsonFocusPowers = sharedPreferences.getString(FOCUS_POWERS_GSON, null);
Type typeFocusPower = new TypeToken<ArrayList<AbstractFocusPower>>() {
}.getType();
ArrayList<AbstractFocusPower> focusPowers;
focusPowers = gsonFocusPowers.fromJson(jsonFocusPowers, typeFocusPower);
if (focusPowers != null) {
this.focusPowers.addAll(checkForNewFocusPowers(focusPowers));
} else {
this.focusPowers = getNewFocusPowerList();
}
Unfortunately this gives me an error which I don't know how to fix.
java.lang.RuntimeException: Unable to create application nl.rekijan.occultistmentalfocushelper.AppExtension: java.lang.RuntimeException: Unable to invoke no-args constructor for class nl.rekijan.occultistmentalfocushelper.mvc.focuspowers.AbstractFocusPower. Registering an InstanceCreator with Gson for this type may fix this problem.
Edit: Not sure why that post is a duplicate. For starters it doesn't have an accepted answer. The answer requires a 3rd party library. The question isn't about multiple subclasses under a single abstract.

have you tried registering a type adapter, something like Using Gson and Abstract Classes ? I always add adapters both for specific formatting (for dates, big decimals, anything where you usually require a very specific format) but also for sub-classing.
In this case however, no adapter is needed, this is.. straight on?
public abstract class AbstractFocusPower implements Parcelable {
// just some property needed to be pushed through a constructor
protected final String myString;
protected AbstractFocusPower(String myString) {
this.myString = myString;
}
}
and then the impl (yeah added toString(), hashCode() and equals() the way I like them to be in domain objects..):
public class AegisFocusPower extends AbstractFocusPower {
boolean imParcelled;
public AegisFocusPower(String myString) {
super(myString);
}
#Override //yup the interface impl
public void parcelMe() {
imParcelled = true;
}
#Override
public String toString() {
return new StringBuilder("{ imParcelled : ").append(imParcelled).append(", myString : ").append(myString).append(" }").toString();
}
#Override
public int hashCode() {
return toString().hashCode();
}
#Override
public boolean equals(Object other) {
if (other == this) {
return true;
} else if (other == null || !(other instanceof AegisFocusPower)) {
return false;
} else {
return other.hashCode() == hashCode();
}
}
}
and then I can run the following junit :
#Test
public void AegisFocusPowerToJsonAndBack(){
// single instance
AegisFocusPower ea = new AegisFocusPower("apa");
String json = GSON.toJson(ea);
assertEquals("{\"imParcelled\":\"false\",\"myString\":\"apa\"}", json);
AegisFocusPower backAtYa = (AegisFocusPower) GSON.fromJson(json, AegisFocusPower.class);
assertEquals(backAtYa, ea);
// A list
AegisFocusPower ea2 = new AegisFocusPower("bepa");
AegisFocusPower ea3 = new AegisFocusPower("cepa");
List<AegisFocusPower> powerList = new ArrayList<>();
powerList.add(ea2);
powerList.add(ea3);
String jsonList = GSON.toJson(powerList);
assertEquals("[{\"imParcelled\":\"false\",\"myString\":\"bepa\"},{\"imParcelled\":\"false\",\"myString\":\"cepa\"}]", jsonList);
List<AegisFocusPower> backAtYaz = Arrays.asList(GSON.fromJson(jsonList,AegisFocusPower[].class));
assertEquals(backAtYaz.get(0), ea2);
assertEquals(backAtYaz.get(1), ea3);
}
whereas GSON is initialized simply like
private static final Gson GSON = (new GsonBuilder()).registerTypeAdapter(Boolean.class, new JsonBooleanDeAndSerializer()).create();
and the type adapter registered for booleans which I use is irrelevant for your problem.
This is.. simple enough and would work for you too?

Check your imports. You may have mistakenly imported wrong class in your pojo. i.e. I have imported android.net.TransportInfo instead of my own TransportInfo class

Android: Send byte[] through Parcelable

I'm trying to pass a list of images to another activity via a Parcelable object in Android. I can convert the images down to a byte[] array fine.
However, I've got a list of these images so there's going to be more than one byte[] array.
Here is my code so far.
public class InvalidItem implements Parcelable {
public String id;
public ArrayList<byte[]> imageList = new ArrayList<>();
public InvalidItem(String id) {
this.id = id;
}
public InvalidItem(Parcel in) {
String[] data = new String[22];
in.readStringArray(data);
this.id= data[0];
this.imageList = data[1];
}
#Override
public int describeContents() {
return 0;
}
#Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeStringArray(new String[]{
this.id,
String.valueOf(this.imageList)
});
}
public static final Parcelable.Creator CREATOR = new Parcelable.Creator() {
public InvalidItem createFromParcel(Parcel in) {
return new InvalidItem(in);
}
public InvalidItem[] newArray(int size) {
return new InvalidItem[size];
}
};
}
As you can see I write the string array which would work for one byte[] array. Is there a way I could have a list of byte[] arrays that I decode into one string and then encode when I want to show the images?
I've tried looking into solutions and people have suggested passing it in the bundle.
However, this application follows a step by step process and requires an object to store the data in.

Class not found when unmarshalling error. Parcelable with byteArray, byte[]

I have an error when using a Parcelable Class.
I'm trying to pass an image as a ByteArray between activities, and eventually to a remote webservice.
java.lang.ClassNotFoundException: ...
Class not found when unmarshalling:
import java.util.UUID;
public class Property implements Parcelable {
#SerializedName("id")
#NonNull
private final String mId;
protected byte[] mImage;
public byte[] getmImage() { return mImage; }
public void setmImage(byte[] image){ mImage = image; }
#SerializedName("generalInformation")
private GeneralInformation mGeneralInformation;
#NonNull
public GeneralInformation getGeneralInformation() {
return mGeneralInformation;
}
public void setGeneralInformation(#NonNull final GeneralInformation generalInformation) {
mGeneralInformation = generalInformation;
}
#NonNull
public String getId() {
return mId;
}
#Override
public boolean equals(final Object o) {
return (o instanceof Property) && ((Property) o).mId.equals(mId);
}
#Override
public int hashCode() {
return mId.hashCode();
}
public static Property create() {
final Property model = new Property(UUID.randomUUID().toString());
model.setGeneralInformation(new GeneralInformation());
return model;
}
#Override
public int describeContents() {
return 0;
}
#Override
public void writeToParcel(#NonNull final Parcel dest, final int flags) {
if(mImage != null) {
dest.writeInt(mImage.length);
dest.writeByteArray(mImage);
}
dest.writeString(mId);
dest.writeParcelable(mGeneralInformation, 0);
}
private Property(#NonNull final String id) {
mId = id;
}
protected Property(final Parcel in) {
if(mImage != null)
{
mImage = new byte[in.readInt()];
in.createByteArray();
}
mId = in.readString();
mGeneralInformation = in.readParcelable(GeneralInformation.class.getClassLoader());
}
public static final Parcelable.Creator<Property> CREATOR = new Parcelable.Creator<Property>() {
public Property createFromParcel(#NonNull final Parcel source) {
return new Property(source);
}
#NonNull
public Property[] newArray(final int size) {
return new Property[size];
}
};
}
Now I have a very limited understanding of the problem(s) I have with this class.
mImage is null when reading the Parcel. (Even when I know for sure that the byteArray is not null when I assign it to the Parcel.) I have tried to initialize mImage in its declaration so it not null but then I have that Class not found when unmarshalling error...
I'm almost sure the problem lies in
protected Property(final Parcel in) {
if(mImage != null)
{
mImage = new byte[in.readInt()];
in.createByteArray();
}
But I don't know how to fix it.
I'm lost for 2 days with this thing :/

Please see the below code for constructor with Parcel object.
protected Property(final Parcel in) {
mImage = new byte[in.readInt()];
in.readByteArray(mImage); // this will read the byte array from Parcel object(in) and store the value in mImage member variable.
mId = in.readString();
mGeneralInformation = in.readParcelable(GeneralInformation.class.getClassLoader());
}

Getting null object after passing it via Intent. My object class implements Parcelable interface.

Activity 1, from where I send my Parcelable object:
Intent intent = new Intent(JobFieldAttribute.this, JobCamera.class);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
Bundle mBundle = new Bundle();
mBundle.putParcelable("FieldData", fieldData);
mBundle.putSerializable("JobTransaction",jobTransaction);
mBundle.putString("imgPos", 0+"");
intent.putExtra("parce",mBundle);
startActivity(intent);
My object class:
public class FieldData implements Parcelable {
private Integer id;
private String value;
private Integer job_transaction_id;
private Integer field_attribute_master_id;
private Boolean required;
private View view;
private String viewType;
private String viewLabel;
private String viewSubLabel;
private String viewHelpText;
//All Getter setter methods
#Override
public int describeContents() {
return 0;
}
#Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeInt(0);
dest.writeString(value);
try{
dest.writeInt(job_transaction_id);
}
catch(Exception e){dest.writeInt(0);}
dest.writeInt(field_attribute_master_id);
try{
dest.writeByte((byte) (required ? 1 : 0));
}
catch(Exception e){dest.writeByte((byte)0);}
try{
dest.writeString(viewType);
}
catch(Exception e){dest.writeString("NOVIEWTYPE");}
try{
dest.writeString(viewLabel);
}
catch(Exception e){dest.writeString("NO LABEL");}
try{
dest.writeString(viewSubLabel);
}
catch(Exception e){dest.writeString("NO SUB LABEL");}
try{
dest.writeString(viewHelpText);
}
catch(Exception e){dest.writeString("NO HELP TEXT");}
}
public static final Parcelable.Creator<FieldData> CREATOR = new Parcelable.Creator<FieldData>() {
#Override
public FieldData createFromParcel(Parcel in) {
FieldData fieldData = new FieldData();
fieldData.id = in.readInt();
Log.i("Pracel in", ">> " + in.readString());
fieldData.value = in.readString();
fieldData.job_transaction_id = in.readInt();
fieldData.field_attribute_master_id = in.readInt();
fieldData.required = in.readByte() != 0;
fieldData.viewType = in.readString();
fieldData.viewLabel = in.readString();
fieldData.viewSubLabel = in.readString();
fieldData.viewHelpText = in.readString();
return fieldData;
}
#Override
public FieldData[] newArray(int size) {
return new FieldData[size];
}
};
}
My second activity, which receives this Parcelable object:
super.onCreate(savedInstanceState);
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
setContentView(R.layout.activity_job_camera);
FieldData fieldData = (FieldData) getIntent().getParcelableExtra("fieldData");
When i print my fieldData object, i get a NullPointerException. I cannot understand the reason for this error.
What am i doing wrong?
I am a newbie at android development and using Parcelable interface for passing object via Intent.
Please help.

You are putting FieldData but trying to get back fieldData. Combine it with #Dmitry Zaitsev's answer: getIntent().getBundleExtra("parce").getParcelableExtra("FieldData");

You're putting Bundle to your Intent extras, not FieldData directly. So, your code should look as follows:
getIntent().getBundleExtra("parce").getParcelableExtra("fieldData");

Trying to sand class object between intents by parcelable

I have a bit trouble implementing Parcelable. Here's how I did it:
public class Player implements Parcelable{
String name;
int score;
#Override
public int describeContents() {
// TODO Auto-generated method stub
return 0;
}
#Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeString(name);
dest.writeInt(score);
}
public Player(Parcel source){
score = source.readInt();
name = source.readString();
}
}
public class MyCreator implements Parcelable.Creator<Player> {
#Override
public Player createFromParcel(Parcel source) {
return new Player(source);
}
#Override
public Player[] newArray(int size) {
return new Player[size];
}
}
This was the whole code implementing Parcelable. Now I'm trying to create a new class object:
Player newPlayer = new Player(null);
newPlayer.name = text;
newPlayer.score = 0;
playersParceledData.add(newPlayer);
zacniIgro.putParcelableArrayListExtra("parceledData", playersParceledData);
This is the line that is bothering me:
Player newPlayer = new Player(null);
Is the fact that I just insrted "null" okay? Or do I have to insert something else between those ()? I was following this example and this isn't explained in it. It says that a new object should be created like this:
Player newPlayer = new Player();
But I am not allowed to do this since I made a constructor.

Create an additional constructor for use cases you're not using Parcel to construct your object, for example
public class Player implements Parcelable{
/* ... */
public Player(Parcel source){
/* ... */
}
public Player(int score, String name){
this.score = score;
this.name = name;
}
}
Then you can construct objects both from Parcel and using an int and an String:
final Player aPlayer = new Player(10000, "SomeRandomPlayerName");
Also, you read the int and the String in inverse order as you write them.