How to convert my values String to custom type in kotlin?

Question

I have a android app i need to save value in sharedpreferences in android using kotlin. sample code below.

my value is : AppdatabaseIMP@43b8de6 ------- its a Appdatabase type so i convert to string like this val APPDBSTR = appDatabase.toString()

save:

val pref = cc.getApplicationContext().getSharedPreferences("MyPrefdd", 0)
val editor = pref.edit()
editor.putString("APPDBSTR", APPDBSTR)
editor.apply()

get:

val pref = context!!.getSharedPreferences("MyPrefdd", 0)
val mFragAPPDBSTR = pref.getString("APPDBSTR", null)

here i can get the value wihout problem, but i want re convert my string to previus type how to do that in kotlin

UPDATE :

companion object {
        /**
         * new instance pattern for fragment
         */
        @JvmStatic
        fun newInstance(myObject: List<TransactionEntity>?, cc: Context, appDatabase: AppDatabase, networkDefinitionProvider: NetworkDefinitionProvider, incoming: TransactionAdapterDirection): SendingFragment {

            val gson = Gson()
            val gson1 = GsonBuilder().create()
            val model = myObject as List<TransactionEntity>
            val IT = gson.toJson(model)
            System.out.println("json representation :" + IT)

            val bo = ByteArrayOutputStream()
        val so = ObjectOutputStream(bo)
        so.writeObject(appdatabase)
        so.flush()
        val serializedObject = String(Base64.encode(bo.toByteArray()))

            val bundle = Bundle()
            bundle.putString("bundleValue", IT)
             bundle.putSerializable("serializedObject",serializedObject)
            val sendFragament: SendingFragment = SendingFragment()
            sendFragament.setArguments(bundle)
            return sendFragament
        }
    }

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {

        val gson = Gson()
        val gson1 = GsonBuilder().create()
        val pref = context!!.getSharedPreferences("MyPrefdd", 0)
        val mFragIT = pref.getString("NEWIT", "")

         val mFragserializedObject = arguments!!.getSerializable("serializedObject") --- i here i can the value 

        }

I got this error :

Caused by: java.io.NotSerializableException: com.crypto.wallet.data.AppDatabase_Impl
                                                                   at java.io.ObjectOutputStream.writeNewObject(ObjectOutputStream.java:1344)
                                                                   at java.io.ObjectOutputStream.writeObjectInternal(ObjectOutputStream.java:1651)
                                                                   at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1497)
                                                                   at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1461)
                                                                   at com.crypto.wallet.activities.SendingFragment$Companion.newInstance(SendingFragment.kt:52)
                                                                   at com.crypto.wallet.activities.MainActivity.setupViewPager(MainActivity.kt:420)
                                                                   at com.crypto.wallet.activities.MainActivity.access$setupViewPager(MainActivity.kt:70)
                                                                   at com.crypto.wallet.activities.MainActivity$onCreate$outgoingTransactionsObserver$1.onChanged(MainActivity.kt:277)
                                                                   at com.crypto.wallet.activities.MainActivity$onCreate$outgoingTransactionsObserver$1.onChanged(MainActivity.kt:70)
                                                                   at android.arch.lifecycle.LiveData.considerNotify(LiveData.java:109)
                                                                   at android.arch.lifecycle.LiveData.dispatchingValue(LiveData.java:126)
                                                                   at android.arch.lifecycle.LiveData.setValue(LiveData.java:282)
                                                                   at android.arch.lifecycle.LiveData$1.run(LiveData.java:87)
                                                                   at android.os.Handler.handleCallback(Handler.java:739)
                                                                   at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                   at android.os.Looper.loop(Looper.java:135)

How to deserialize it ?

Answer 1

What you are getting there when calling toString is only a hash of the object in the memory. It does not contain the actual object values, so it can not be restored this way.

https://developer.android.com/reference/java/lang/Object.html#toString()
The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object.

You need to serialize the whole object for the restoration to work. Depending on your class, this could be as simple as extending Serializable and getting the String as described in this answer: https://stackoverflow.com/a/8887244/4193263

ByteArrayOutputStream bo = new ByteArrayOutputStream();
ObjectOutputStream so = new ObjectOutputStream(bo);
so.writeObject(myObject);
so.flush();
String serializedObject = new String(Base64.encodeBase64(bo.toByteArray()));