Use Handler.postDelayed() extension to put the lambdas outside parentheses.

app/src/main/java/com/github/libretube/ui/fragments/PlayerFragment.kt

@@ -31,6 +31,7 @@ import androidx.constraintlayout.motion.widget.MotionLayout
 import androidx.core.net.toUri
 import androidx.core.os.ConfigurationCompat
 import androidx.core.os.bundleOf
+import androidx.core.os.postDelayed
 import androidx.core.text.parseAsHtml
 import androidx.core.view.isVisible
 import androidx.fragment.app.activityViewModels
@@ -210,9 +211,9 @@ class PlayerFragment : BaseFragment(), OnlinePlayerOptions {
                 PlayerEvent.Background -> {
                     playOnBackground()
                     // wait some time in order for the service to get started properly
-                    handler.postDelayed({
+                    handler.postDelayed(500) {
                         activity?.finish()
-                    }, 500)
+                    }
                 }
                 else -> {
                 }
@@ -476,10 +477,10 @@ class PlayerFragment : BaseFragment(), OnlinePlayerOptions {
             channelId,
             true
         )
-        handler.postDelayed({
+        handler.postDelayed(500) {
             NavigationHelper.startAudioPlayer(requireContext())
             killPlayerFragment()
-        }, 500)
+        }
     }
 
     private fun setFullscreen() {

app/src/main/java/com/github/libretube/ui/fragments/WatchHistoryFragment.kt

@@ -6,6 +6,7 @@ import android.os.Looper
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
+import androidx.core.os.postDelayed
 import androidx.core.view.updatePadding
 import androidx.fragment.app.activityViewModels
 import androidx.recyclerview.widget.ItemTouchHelper
@@ -144,7 +145,7 @@ class WatchHistoryFragment : BaseFragment() {
         })
 
         // add a listener for scroll end, delay needed to prevent loading new ones the first time
-        Handler(Looper.getMainLooper()).postDelayed({
+        Handler(Looper.getMainLooper()).postDelayed(200) {
             binding.historyScrollView.viewTreeObserver.addOnScrollChangedListener {
                 if (!binding.historyScrollView.canScrollVertically(1) && !isLoading) {
                     isLoading = true
@@ -152,6 +153,6 @@ class WatchHistoryFragment : BaseFragment() {
                     isLoading = false
                 }
             }
-        }, 200)
+        }
     }
 }

app/src/main/java/com/github/libretube/ui/tools/SleepTimer.kt

@@ -3,6 +3,8 @@ package com.github.libretube.ui.tools
 import android.content.Context
 import android.os.Handler
 import android.os.Looper
+import android.os.Process
+import androidx.core.os.postDelayed
 import com.github.libretube.R
 import com.github.libretube.constants.PreferenceKeys
 import com.github.libretube.ui.activities.MainActivity
@@ -25,8 +27,7 @@ object SleepTimer {
             ""
         ).ifEmpty { return }
 
-        handler.postDelayed(
+        handler.postDelayed(breakReminderPref.toLong() * 60 * 1000) {
-            {
             var killApp = true
             val mainActivity = context as? MainActivity ?: return@postDelayed
             val snackBar = Snackbar.make(
@@ -38,25 +39,20 @@ object SleepTimer {
                     killApp = false
                 }
             snackBar.show()
-                (0..REACTION_INTERVAL).forEach {
+            for (i in 0..REACTION_INTERVAL) {
-                    handler.postDelayed({
+                handler.postDelayed(i * 1000) {
-                        val remainingTime = " (${REACTION_INTERVAL - it})"
+                    val remainingTime = " (${REACTION_INTERVAL - i})"
                     snackBar.setText(context.getString(R.string.take_a_break) + remainingTime)
-                    }, it * 1000)
                 }
-                handler.postDelayed(
+            }
-                    killApp@{
+            handler.postDelayed(REACTION_INTERVAL * 1000) {
-                        if (!killApp) return@killApp
+                if (killApp) {
-
                     // kill the application
                     mainActivity.finishAffinity()
                     mainActivity.finish()
-                        android.os.Process.killProcess(android.os.Process.myPid())
+                    Process.killProcess(Process.myPid())
-                    },
+                }
-                    REACTION_INTERVAL * 1000
+            }
-                )
+        }
-            },
-            breakReminderPref.toLong() * 60 * 1000
-        )
     }
 }

app/src/main/java/com/github/libretube/ui/views/CustomExoPlayerView.kt

@@ -439,12 +439,12 @@ internal class CustomExoPlayerView(
             .setDuration((ANIMATION_DURATION * 1.5).toLong())
             .withEndAction {
                 // move the text back into the button
-                handler.postDelayed({
+                handler.postDelayed(100) {
                     textView.animate()
                         .setDuration(ANIMATION_DURATION / 2)
                         .translationX(0f)
                         .start()
-                }, 100)
+                }
             }
     }
 

app/src/main/java/com/github/libretube/util/NavigationHelper.kt

@@ -9,6 +9,7 @@ import android.os.Handler
 import android.os.Looper
 import androidx.appcompat.app.AppCompatActivity
 import androidx.core.os.bundleOf
+import androidx.core.os.postDelayed
 import com.github.libretube.R
 import com.github.libretube.constants.IntentData
 import com.github.libretube.constants.PreferenceKeys
@@ -74,9 +75,9 @@ object NavigationHelper {
                 channelId,
                 keepQueue
             )
-            handler.postDelayed({
+            handler.postDelayed(500) {
                 startAudioPlayer(context)
-            }, 500)
+            }
             return
         }