NullPointerException when you set a text in a TextView

When trying to set text in a TextView in the following way:

Class - > FavouritePet.java

public class FavouritePet extends AppCompatActivity {
private ArrayList<Pet> pets;
private RecyclerView rvPets2;
private TextView numeroLikes, nombreMascota;
private ImageView foto;

@Override
protected void onCreate (Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    setContentView(R.layout.favourite_pet);

    //Establecemos la Toolbar
    Toolbar toolbar = (Toolbar) findViewById(R.id.myActionBar);
    setSupportActionBar(toolbar);
    //Para el boton de back
    //        getSupportActionBar().setDisplayHomeAsUpEnabled(true);


    rvPets2 = (RecyclerView) findViewById(R.id.rvPets2);
    LinearLayoutManager llm = new LinearLayoutManager(this);
    llm.setOrientation(LinearLayoutManager.VERTICAL);
    rvPets2.setLayoutManager(llm);
    inicializarAdaptador();

    pets = new ArrayList<Pet>();
    ordenarMascotas(pets);

    //Bundle
    Bundle bndl=getIntent().getExtras();
    Pet pet = inicializarMascotas(bndl);
    String nombreMascota = pet.getPetName();
    int numeroLikes = pet.getNumberOfLikes();
    int foto = pet.getFoto();

    this.nombreMascota = (TextView) findViewById(R.id.tvPetNameFavourite);
    this.numeroLikes = (TextView) findViewById(R.id.tvLikesNumberFavourite);
    this.foto = (ImageView) findViewById(R.id.ivFavouritePetImage);

    //NullPointerException -> Estoy tratando de settear un texto en un objeto nulo.
    this.nombreMascota.setText(nombreMascota);
    this.numeroLikes.setText(numeroLikes);
    this.foto.setImageResource(foto);


}
public ArrayList<Pet> ordenarMascotas(ArrayList<Pet> pets){

    Collections.sort(pets, new Comparator() {
        @Override
        public int compare(Object o, Object t1) {
            return 0;
        }
        public int compare(Pet p1, Pet p2) {
            return new Integer(p2.getNumberOfLikes()).compareTo(new Integer(p1.getNumberOfLikes()));
        }

    });
    return pets;
}
public Pet inicializarMascotas(Bundle bndl){
    String nombreMascota = bndl.getString(String.valueOf(R.string.nombre_mascota));
    int numeroLikes = bndl.getInt(String.valueOf(R.string.numberOfLikes));
    int foto = bndl.getInt(String.valueOf(R.string.foto));
    Pet p1 = new Pet (numeroLikes,nombreMascota,foto);
    pets.add(p1);
    return p1;
}
public void inicializarAdaptador(){
    FavouriteAdapter fva = new FavouriteAdapter(pets,this);
    rvPets2.setAdapter(fva);
}

}

The identifiers are correctly written in xml.

Layout - > cardview_favourite_pets.xml

   <?xml version="1.0" encoding="utf-8"?>
 <android.support.v7.widget.CardView
     xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
     app:cardCornerRadius="@dimen/cardCornerRadius"
    >
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        >
        <include
            android:id="@+id/myActionBar"
            layout="@layout/actionbar"
            >
        </include>
        <ImageView
            android:id="@+id/ivFavouritePetImage"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="@dimen/margin_left1"
            android:src="@drawable/perro"
            />
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            >
            <ImageView
                android:id="@+id/ivEmptyBoneFavourite"
                android:layout_width="25dp"
                android:layout_height="25dp"
                android:src="@drawable/dog_bone_48"
                android:layout_marginLeft="@dimen/margin_left3"
                />
            <TextView
                android:id="@+id/tvPetNameFavourite"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginLeft="@dimen/margin_left1"
                android:text="@string/nombre_mascota"
                android:textStyle="bold"
                android:textSize="@dimen/textSize"
                />
            <TextView
                android:id="@+id/tvLikesNumberFavourite"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginLeft="@dimen/margin_left2"
                android:textSize="@dimen/textSize"
                android:textStyle="bold"
                android:text="@string/numberOfLikes"
                />
            <ImageView
                android:id="@+id/ivFullBoneFavourite"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:src="@drawable/dog_bone_48_1"
                android:layout_marginLeft="@dimen/margin_left3"
                />
         </LinearLayout>
     </LinearLayout>
 </android.support.v7.widget.CardView>

I think the error should be somewhere in the xml because I do not see any error in the Java code. Looking in the xml code, I realized that in android:context was assigned the Layout .MainActivity , when in fact I had to assign the corresponding layout, in my case .FavouritePet (Copy-paste things hehe). I leave the xml code to see if someone can help me out.

Layout - > favourite_pet.xml

    <?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:paddingBottom="@dimen/activity_vertical_margin"
        android:paddingLeft="@dimen/activity_horizontal_margin"
        android:paddingRight="@dimen/activity_horizontal_margin"
        android:paddingTop="@dimen/activity_vertical_margin"
        tools:context="es.uclm.mylittlepets.FavouritePet">

        <android.support.v7.widget.RecyclerView
            android:id="@+id/rvPets2"
            android:layout_width="match_parent"
            android:layout_height="match_parent">
        </android.support.v7.widget.RecyclerView>
    </RelativeLayout>

The error he gives me is this:

08-22 09:10:52.142 2716-2716/es.uclm.mylittlepets E/AndroidRuntime: FATAL EXCEPTION: main
Process: es.uclm.mylittlepets, PID: 2716
java.lang.RuntimeException: Unable to start activity ComponentInfo{es.uclm.mylittlepets/es.uclm.mylittlepets.FavouritePet}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
    at android.app.ActivityThread.-wrap11(ActivityThread.java)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:148)
    at android.app.ActivityThread.main(ActivityThread.java:5417)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
 Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
    at es.uclm.mylittlepets.FavouritePet.onCreate(FavouritePet.java:59)
    at android.app.Activity.performCreate(Activity.java:6237)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 
    at android.app.ActivityThread.-wrap11(ActivityThread.java) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) 
    at android.os.Handler.dispatchMessage(Handler.java:102) 
    at android.os.Looper.loop(Looper.java:148) 
    at android.app.ActivityThread.main(ActivityThread.java:5417) 
    at java.lang.reflect.Method.invoke(Native Method)

EDIT: Here I leave the debugging result to the method inicializarMascotas(bndl)

The Pet class is:

public class Pet {
//Atributos
private int  numberOfLikes, foto;
private String petName;

//Constructor
public Pet (int numberOfLines, String petName, int foto){
    this.numberOfLikes=numberOfLines;
    this.petName=petName;
    this.foto = foto;
}

public int getNumberOfLikes() {
    return numberOfLikes;
}

public void setNumberOfLikes(int numberOfLines) {
    this.numberOfLikes = numberOfLines;
}

public String getPetName() {
    return petName;
}

public void setPetName(String petName) {
    this.petName = petName;
}

public int getFoto(){
    return foto;
}

public void setFoto (int foto) {
    this.foto = foto;
}

I think there is no problem executing the getPetName() method

I add the adapter class - > FavouriteAdapter.java

public class FavouriteAdapter extends RecyclerView.Adapter<FavouriteAdapter.FavouriteViewHolder>{
ArrayList<Pet> pets;
Activity activity;

public FavouriteAdapter(ArrayList<Pet> pets, Activity activity){
    this.pets=pets;
    this.activity = activity;
}
@Override
public FavouriteViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.cardview_favourite_pets,parent,false);
    return new FavouriteViewHolder(v);
}

@Override
public void onBindViewHolder(FavouriteViewHolder holder, int position) {
    Pet pet = pets.get(position);
    asignarAtributos(holder,pet);

}

@Override
public int getItemCount() {
    return pets.size();
}
public void asignarAtributos(FavouriteViewHolder holder, Pet pet){
    holder.petName.setText(pet.getPetName());
    holder.numberOfLikes.setText(String.valueOf(pet.getNumberOfLikes()));
    holder.ibStar.setImageResource(R.drawable.star_48);
    holder.ivCardview.setImageResource(pet.getFoto());
    holder.ivFullBone.setImageResource(R.drawable.dog_bone_48_1);
    holder.ivEmptyBone.setImageResource(R.drawable.dog_bone_48);
}
public static class FavouriteViewHolder extends RecyclerView.ViewHolder{
    //Atributos
    private TextView numberOfLikes, petName;
    private ImageButton ibStar;
    private ImageView ivCardview, ivFullBone, ivEmptyBone;

    public FavouriteViewHolder(View itemView) {
        super(itemView);
        asociarElementos(itemView);
    }
    public void asociarElementos(View itemView){
        numberOfLikes = (TextView) itemView.findViewById(R.id.tvLikesNumberFavourite);
        petName = (TextView) itemView.findViewById(R.id.tvPetNameFavourite);
        ibStar = (ImageButton) itemView.findViewById(R.id.ibStar);
        ivCardview = (ImageView) itemView.findViewById(R.id.ivFavouritePetImage);
        ivFullBone = (ImageView) itemView.findViewById(R.id.ivFullBoneFavourite);
        ivEmptyBone = (ImageView) itemView.findViewById(R.id.ivEmptyBoneFavourite);
    }
}

}