show an Edit button if there is only 1 item selected

app/src/main/kotlin/com/simplemobiletools/applauncher/adapters/RecyclerAdapter.kt

@@ -28,6 +28,9 @@ class RecyclerAdapter(val act: Activity, val launchers: List<AppLauncher>, val i
     val deleteMode = object : ModalMultiSelectorCallback(multiSelector) {
         override fun onActionItemClicked(mode: ActionMode?, item: MenuItem?): Boolean {
             when (item?.itemId) {
+                R.id.cab_edit -> {
+
+                }
                 R.id.cab_delete -> {
                     val positions = multiSelector.selectedPositions
                     val deleteIds = ArrayList<String>(positions.size)
@@ -51,6 +54,12 @@ class RecyclerAdapter(val act: Activity, val launchers: List<AppLauncher>, val i
             act.menuInflater.inflate(R.menu.cab, menu)
             return true
         }
+
+        override fun onPrepareActionMode(actionMode: ActionMode?, menu: Menu?): Boolean {
+            val menuItem = menu?.findItem(R.id.cab_edit)
+            menuItem?.isVisible = multiSelector.selectedPositions.size == 1
+            return true
+        }
     }
 
     override fun onBindViewHolder(holder: ViewHolder, position: Int) {
@@ -112,6 +121,7 @@ class RecyclerAdapter(val act: Activity, val launchers: List<AppLauncher>, val i
                 } else {
                     actMode?.title = selectedCnt.toString()
                 }
+                actMode?.invalidate()
             } else {
                 itemClick(appLauncher)
             }

app/src/main/res/menu/cab.xml

@@ -1,6 +1,11 @@
 <?xml version="1.0" encoding="utf-8"?>
 <menu xmlns:android="http://schemas.android.com/apk/res/android"
       xmlns:app="http://schemas.android.com/apk/res-auto">
+    <item
+        android:id="@+id/cab_edit"
+        android:icon="@mipmap/edit"
+        android:title="@string/edit"
+        app:showAsAction="ifRoom"/>
     <item
         android:id="@+id/cab_delete"
         android:icon="@mipmap/delete"

app/src/main/res/values/strings.xml

@@ -1,6 +1,7 @@
 <resources>
     <string name="app_name">Simple App Launcher</string>
     <string name="delete">Delete</string>
+    <string name="edit">Edit</string>
 
     <!-- About -->
     <string name="about">About</string>