extras.getString() 在 Kotlin Android 中返回 null

Question

The result is always return null, I don't know what mistake, I have seen other people problems I am not getting what I need exactly.

class DatabaseLists(private val context: Context?) {
    private lateinit var database: SQLiteDatabase

    val getPrayerContentList: ArrayList<PrayerModel>
        @SuppressLint("Recycle")
        get() {
            database = DatabaseOpenHelper(context).readableDatabase
            val cursor: Cursor = database.query(
                "table_prayer",
                null,
                null,
                null,
                null,
                null,
                null,
                null
            )

            val contentList = ArrayList<PrayerModel>()
            if (cursor.moveToFirst()) {
                while (!cursor.isAfterLast) {
                    val contents = PrayerModel(
                        cursor.getString(cursor.getColumnIndex("prayer_name")),
                        cursor.getString(cursor.getColumnIndex("ayah_name")),
                        cursor.getString(cursor.getColumnIndex("arabic")),
                        cursor.getString(cursor.getColumnIndex("latin")),
                        cursor.getString(cursor.getColumnIndex("translate")),
                        cursor.getString(cursor.getColumnIndex("description"))
                    )
                    contentList.add(contents)
                    cursor.moveToNext()
                    if (cursor.isClosed) {
                        cursor.close()
                    }
                }
            }
            return contentList
        }

class PrayerActivity : AppCompatActivity(), MainContract.MainView {

    private lateinit var binding: ActivityPrayerBinding
    private var database: SQLiteDatabase? = null
    private lateinit var preferences: SharedPreferences
    private lateinit var editor: SharedPreferences.Editor
    lateinit var carlist: ArrayList<PrayerModel>
    private lateinit var prayerContentList: MutableList<PrayerModel>
    private lateinit var prayerAdapter: PrayerAdapter
    private lateinit var mainPresenterImpl: MainPresenterImpl

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        binding = DataBindingUtil.setContentView(this, R.layout.activity_prayer)

        setSupportActionBar(binding.toolbar)
 
        preferences = PreferenceManager.getDefaultSharedPreferences(this)
        editor = preferences.edit()

        PreferenceManager.getDefaultSharedPreferences(this)
        database = DatabaseOpenHelper(this).readableDatabase
        prayerContentList = DatabaseLists(this).getPrayerContentList

        mainPresenterImpl = MainPresenterImpl(this, this)
        initMainContent()

    }

    override fun initMainContent() {
             val verticalLayout = LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false)
             binding.rvMainContent.layoutManager = verticalLayout
             prayerAdapter = PrayerAdapter(this, prayerContentList)
             binding.rvMainContent.adapter = prayerAdapter
    }

}

data class PrayerModel  (
    val strPrayerName: String?,
    val strAyahName: String?,
    val strContentArabic: String?,
    val strContentLatin: String?,
    val strContentTranslation: String?,
    val strContentDescription: String?)

myAdapter

class PrayerAdapter(context: Context, private val prayerContentList: MutableList<PrayerModel>) :
    RecyclerView.Adapter<PrayerViewHolder>() {

    private val context: Context? = null
    private val inflater = LayoutInflater.from(context)
    private var currentIndex: Int = -1

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): PrayerViewHolder {
        return PrayerViewHolder(inflater.inflate(R.layout.item_prayer_content, parent, false))
    }

    override fun getItemCount(): Int {
        return prayerContentList.size
    }

    override fun onBindViewHolder(holder: PrayerViewHolder, position: Int) {
        val strContentArabic = prayerContentList[position].strContentArabic
        val strContentLatin = prayerContentList[position].strContentLatin
        val strContentTranslation = prayerContentList[position].strContentTranslation
        val strContentDescription = prayerContentList[position].strContentDescription

        val strPrayerName = prayerContentList[position].strPrayerName
        val strAyahName = prayerContentList[position].strAyahName

        holder.tvContentPrayerName.text = strPrayerName
        holder.tvContentAyahName.text = strAyahName

        holder.itemView.setOnClickListener { v ->

            val context: Context = v.context
            val intent = Intent(context, PrayerReadActivity::class.java)

            intent.putExtra("ARABIC_TEXT", strContentArabic?.get(position))
            intent.putExtra("LATIN_TEXT", strContentLatin!![position])
            intent.putExtra("TRANSLATION_TEXT", strContentTranslation!![position])
            intent.putExtra("DESCRIPTION_TEXT", strContentDescription!![position])

            context.startActivity(intent)
            Log.d(TAG, "-->name = $strContentArabic")

        }
    }
}

my 2Activity can have code like this, and trying to get that string extra in another activity but is returning null?

class PrayerReadActivity() : AppCompatActivity() {

    private var database: SQLiteDatabase? = null
    private lateinit var prayerContentList: MutableList<PrayerModel>

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        setContentView(R.layout.activity_prayer_read)

        LockOrientation(this).lock()

        PreferenceManager.getDefaultSharedPreferences(this)

        database = DatabaseOpenHelper(this).readableDatabase
        prayerContentList = DatabaseLists(this).getPrayerContentList


        val extras = intent.extras
        if (null != extras) {
            val arabic = extras.getString("ARABIC_TEXT").toString()
            val latin = extras.getString("LATIN_TEXT").toString()
            val translation = extras.getString("TRANSLATION_TEXT").toString()
            val description = extras.getString("DESCRIPTION_TEXT").toString()
            Log.d(ContentValues.TAG, "-->arabic = $arabic")

            tvContentArabic2.text = arabic
            tvContentLatin2.text = latin
            tvContentTranslation2.text = translation
            tvContentDescription2.text = description

            Log.d(ContentValues.TAG, "-->arabic = $arabic")
            Log.d(ContentValues.TAG, "-->latin = $latin")
            Log.d(ContentValues.TAG, "-->translation = $translation")
            Log.d(ContentValues.TAG, "-->description = $description")

        }

I tried by replacing

val arabic = intent.getStringExtra("ARABIC_TEXT").toString()

also still it is returning null?

2021-07-22 22:31:16.411 9607-9607/com.example.yasiin D/ContentValues: -->arabic = null
2021-07-22 22:31:16.411 9607-9607/com.example.yasiin D/ContentValues: -->arabic = null
2021-07-22 22:31:16.411 9607-9607/com.example.yasiin D/ContentValues: -->latin = null
2021-07-22 22:31:16.411 9607-9607/com.example.yasiin D/ContentValues: -->translation = null
2021-07-22 22:31:16.411 9607-9607/com.example.yasiin D/ContentValues: -->description = null

Answer 1

Try replacing this

intent.putExtra("ARABIC_TEXT", strContentArabic?.get(position))
intent.putExtra("LATIN_TEXT", strContentLatin!![position])
intent.putExtra("TRANSLATION_TEXT", strContentTranslation!![position])
intent.putExtra("DESCRIPTION_TEXT", strContentDescription!![position])

With this

intent.putExtra("ARABIC_TEXT", strContentArabic)
intent.putExtra("LATIN_TEXT", strContentLatin)
intent.putExtra("TRANSLATION_TEXT", strContentTranslation)
intent.putExtra("DESCRIPTION_TEXT", strContentDescription)

You have already have the string, just put it in the extras.

Answer 2

Please just try the below line of code to update and check in your PrayerActivity, for this you can create one interface callback and call interface method(varargs with multiple params or string or pojo class) from adapter class where you are opening intent currently, then from PrayerActivity activity you can open it

 val intent = Intent(this@PrayerActivity, PrayerReadActivity::class.java)
 intent.putExtra("ARABIC_TEXT", strContentArabic?.get(position))
 intent.putExtra("LATIN_TEXT", strContentLatin!![position])
 intent.putExtra("TRANSLATION_TEXT", strContentTranslation!![position])
 intent.putExtra("DESCRIPTION_TEXT", strContentDescription!![position])

startActivity(intent)

hope it may help you