How to Pass a List of Objects from activity A to activity B in Kotlin?

Question

I have 2 Activities, I want to pass an arraylist of an Object and show it on a ListView

Activity A:

     btnGuardar.setOnClickListener{

                if(edtNombre.text.toString().equals("") || 
                     edtApellido.text.toString().equals("") || 
                     edtFecha.text.toString().equals("")){

                    Toast.makeText(this@Main2Activity, "Debes llenar todos los campos!", Toast.LENGTH_SHORT).show()
                }else{
                    var estadoSel : String
                    estadoSel = estado.onItemSelectedListener.toString()
                   var per = Persona(edtNombre.text.toString(),edtApellido.text.toString(),estadoSel,edtFecha.text.toString())
                    personas.add(per)
                    val intent = Intent(this@Main2Activity,Main3Activity::class.java)
                    //intent.putExtra("Personas",  personas as Serializable)
                    intent.putParcelableArrayListExtra("Personas", ArrayList(personas))
                    edtFecha.text = null
                    edtApellido.text = null
                    edtNombre.text = null
                    estado.setSelection(0)
                    Toast.makeText(this@Main2Activity, "Registro Guardado", Toast.LENGTH_SHORT).show()
                }
            }

Activity B:

 override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main3)
        supportActionBar?.setDisplayHomeAsUpEnabled(true)
        //val intent = Intent()
        val bundle = getIntent().extras
        var arr  = bundle?.getParcelableArrayList<Persona>("Personas")!!
        //var arr : ArrayList<Persona> = (ArrayList<Persona>())intent.getSerializableExtra("Personas")
        //intent.getSerializableExtra("Personas")
        //arr = intent.extras!!.get("Personas")
        val adapter = ArrayAdapter(this, android.R.layout.simple_list_item_1, arr)
        listaPersonas.adapter = adapter
    }

But I'm getting a Null Pointer Exception

Answer 1

In your activity B to get your list try like the following

var arr = this.getIntent().getParcelableArrayListExtra<Parcelable>("Personas")

and make sure your Persona is extend Parcelable like below.

class Persona() : Parcelable {
   // ....
   @Override
   public void writeToParcel(Parcel dest, int flags) {
       //....
   }

   private void readFromParcel(Parcel in) {
      //....
   }
   override fun describeContents(): Int {
      return 0
   }

   companion object CREATOR : Creator<Persona> {
    override fun createFromParcel(parcel: Parcel): Persona{
      return Persona(parcel)
    }

    override fun newArray(size: Int): Array<Persona?> {
      return arrayOfNulls(size)
    }
  }

}