Marqueetextview

package org.oppia.android.app.customview

import android.content.Context
import android.text.TextUtils
import android.util.AttributeSet
import android.view.View
import androidx.appcompat.widget.AppCompatTextView
import androidx.core.view.ViewCompat
import androidx.fragment.app.Fragment
import androidx.fragment.app.FragmentManager
import org.oppia.android.app.translation.AppLanguageResourceHandler
import org.oppia.android.app.view.ViewComponentFactory
import org.oppia.android.app.view.ViewComponentImpl
import javax.inject.Inject

/** The custom Textview class for toolbar with Marquee effect. */
class MarqueeToolbarTextView @JvmOverloads constructor(
  context: Context,
  attrs: AttributeSet? = null,
  defStyle: Int = android.R.attr.textViewStyle
) : AppCompatTextView(context, attrs, defStyle), View.OnClickListener {

  @Inject
  lateinit var resourceHandler: AppLanguageResourceHandler

  private val isRtl by lazy {
      resourceHandler.getLayoutDirection() == ViewCompat.LAYOUT_DIRECTION_RTL
  }

  init {
    setOnClickListener(this)
    ellipsize = TextUtils.TruncateAt.MARQUEE
    if (isRtl) {
      textDirection = View.TEXT_DIRECTION_RTL
    } else {
      textDirection = View.TEXT_DIRECTION_LTR
    }
  }

  override fun onClick(v: View?) {
    isSelected = true
  }

  override fun onAttachedToWindow() {
    super.onAttachedToWindow()

    val viewComponentFactory = FragmentManager.findFragment<Fragment>(this) as ViewComponentFactory
    val viewComponent = viewComponentFactory.createViewComponent(this) as ViewComponentImpl
    viewComponent.inject(this)
  }
}

For the current code, the reason you're getting not initialized error is because init{} is called as part of the constructor, and is trying to access resourceHandler which isn't initialized until inject(this) is called in onAttachedToWindow (which happens after construction). You'll need to move the text direction logic to happen in onAttachedToWindow() after injection.