diff --git a/.gitignore b/.gitignore
index aa724b7..3df0749 100644
--- a/.gitignore
+++ b/.gitignore
@@ -13,3 +13,4 @@
 .externalNativeBuild
 .cxx
 local.properties
+/.idea/runConfigurations.xml
diff --git a/app/src/main/java/com/example/myapplication/fileSystem/byTypeFileLister/DocumentAdapter.kt b/app/src/main/java/com/example/myapplication/fileSystem/byTypeFileLister/DocumentLister.kt
similarity index 90%
rename from app/src/main/java/com/example/myapplication/fileSystem/byTypeFileLister/DocumentAdapter.kt
rename to app/src/main/java/com/example/myapplication/fileSystem/byTypeFileLister/DocumentLister.kt
index c7fbe4b..c451cf2 100644
--- a/app/src/main/java/com/example/myapplication/fileSystem/byTypeFileLister/DocumentAdapter.kt
+++ b/app/src/main/java/com/example/myapplication/fileSystem/byTypeFileLister/DocumentLister.kt
@@ -7,7 +7,7 @@ import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
 import java.io.File
 
-class DocumentLister : Lister() {
+class DocumentLister : Lister {
   companion object {
     val instance by lazy { DocumentLister() }
     val directories = listOf("Documents", "Download")
@@ -31,7 +31,7 @@ class DocumentLister : Lister() {
     return
   }
 
-  fun dateOrderedList(): List<String> {
+  override fun dateOrderedList(): List<String> {
     val wrappedFileList = mutableListOf<WrappedFile>()
     documentList.forEach { wrappedFileList.add(WrappedFile(File(it))) }
     wrappedFileList.sortBy { it.lastModifiedTime }
@@ -40,7 +40,7 @@ class DocumentLister : Lister() {
     return result
   }
 
-  fun sizeOrderedList(): List<String> {
+  override fun sizeOrderedList(): List<String> {
     val wrappedFileList = mutableListOf<WrappedFile>()
     documentList.forEach { wrappedFileList.add(WrappedFile(File(it))) }
     wrappedFileList.sortBy { it.size }
@@ -49,7 +49,7 @@ class DocumentLister : Lister() {
     return result
   }
 
-  fun getFullSize(): ULong {
+  override fun getFullSize(): ULong {
     var size = 0UL
     val wrappedFileList = mutableListOf<WrappedFile>()
     documentList.forEach { wrappedFileList.add(WrappedFile(File(it))) }
diff --git a/app/src/main/java/com/example/myapplication/fileSystem/byTypeFileLister/ImageLister.kt b/app/src/main/java/com/example/myapplication/fileSystem/byTypeFileLister/ImageLister.kt
index cd21a02..01cdfeb 100644
--- a/app/src/main/java/com/example/myapplication/fileSystem/byTypeFileLister/ImageLister.kt
+++ b/app/src/main/java/com/example/myapplication/fileSystem/byTypeFileLister/ImageLister.kt
@@ -7,14 +7,14 @@ import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
 import java.io.File
 
-class ImageLister private constructor() : Lister() {
+class ImageLister private constructor() : Lister {
   companion object {
     val instance by lazy { ImageLister() }
     val directories = listOf("DCIM", "Pictures", "Download")
-    val regex = "\\.(jpg|png|jpeg|webp)".toRegex()
+    val regex = "\\.(jpg|png|jpeg|webp)$".toRegex()
   }
 
-  val imageList = mutableListOf<String>()
+  private val imageList = mutableListOf<String>()
 
   fun initialize(onFinished: (() -> Unit)? = null) {
     imageList.clear()
@@ -31,7 +31,7 @@ class ImageLister private constructor() : Lister() {
     return
   }
 
-  fun dateOrderedList(): List<String> {
+  override fun dateOrderedList(): List<String> {
     val wrappedFileList = mutableListOf<WrappedFile>()
     imageList.forEach { wrappedFileList.add(WrappedFile(File(it))) }
     wrappedFileList.sortBy { it.lastModifiedTime }
@@ -40,7 +40,7 @@ class ImageLister private constructor() : Lister() {
     return result
   }
 
-  fun sizeOrderedList(): List<String> {
+  override fun sizeOrderedList(): List<String> {
     val wrappedFileList = mutableListOf<WrappedFile>()
     imageList.forEach { wrappedFileList.add(WrappedFile(File(it))) }
     wrappedFileList.sortBy { it.size }
@@ -49,7 +49,7 @@ class ImageLister private constructor() : Lister() {
     return result
   }
 
-  fun getFullSize(): ULong {
+  override fun getFullSize(): ULong {
     var size = 0UL
     val wrappedFileList = mutableListOf<WrappedFile>()
     imageList.forEach { wrappedFileList.add(WrappedFile(File(it))) }
diff --git a/app/src/main/java/com/example/myapplication/fileSystem/byTypeFileLister/Lister.kt b/app/src/main/java/com/example/myapplication/fileSystem/byTypeFileLister/Lister.kt
index b5aac21..0dd9775 100644
--- a/app/src/main/java/com/example/myapplication/fileSystem/byTypeFileLister/Lister.kt
+++ b/app/src/main/java/com/example/myapplication/fileSystem/byTypeFileLister/Lister.kt
@@ -1,4 +1,34 @@
 package com.example.myapplication.fileSystem.byTypeFileLister
 
-abstract class Lister {
-}
\ No newline at end of file
+import java.io.File
+
+interface Lister {
+  fun dateOrderedList(): List<String>
+
+  fun sizeOrderedList(): List<String>
+
+  fun getFullSize(): ULong
+
+  fun walkDir(
+    directory: File,
+    list: MutableList<String>,
+    pattern: Regex,
+    ignoreDotFile: Boolean = true
+  ) {
+    if (!directory.exists() || !directory.isDirectory) {
+      return
+    }
+    directory.listFiles()?.forEach {
+      if (ignoreDotFile && !it.name.startsWith(".")) {
+        if (it.isDirectory) {
+          walkDir(it, list, pattern)
+        } else if (it.isFile) {
+          if (it.name.contains(pattern)) {
+            list.add(it.path)
+          }
+        }
+      }
+    }
+  }
+
+}
diff --git a/app/src/main/java/com/example/myapplication/fileSystem/byTypeFileLister/MusicLister.kt b/app/src/main/java/com/example/myapplication/fileSystem/byTypeFileLister/MusicLister.kt
index bbcc82b..cb4642b 100644
--- a/app/src/main/java/com/example/myapplication/fileSystem/byTypeFileLister/MusicLister.kt
+++ b/app/src/main/java/com/example/myapplication/fileSystem/byTypeFileLister/MusicLister.kt
@@ -7,15 +7,15 @@ import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
 import java.io.File
 
-class MusicLister : Lister() {
+class MusicLister : Lister {
   companion object {
     val instance by lazy { MusicLister() }
     val directories =
       listOf("Recordings", "Download", "Audiobooks", "Music", "Podcasts", "Ringtones")
-    val regex = "\\.(mp3|ogg|aac|wav)".toRegex()
+    val regex = "\\.(mp3|ogg|aac|wav)$".toRegex()
   }
 
-  val musicList = mutableListOf<String>()
+  private val musicList = mutableListOf<String>()
 
   fun initialize(onFinished: (() -> Unit)? = null) {
     musicList.clear()
@@ -32,7 +32,7 @@ class MusicLister : Lister() {
     return
   }
 
-  fun dateOrderedList(): List<String> {
+  override fun dateOrderedList(): List<String> {
     val wrappedFileList = mutableListOf<WrappedFile>()
     musicList.forEach { wrappedFileList.add(WrappedFile(File(it))) }
     wrappedFileList.sortBy { it.lastModifiedTime }
@@ -41,7 +41,7 @@ class MusicLister : Lister() {
     return result
   }
 
-  fun sizeOrderedList(): List<String> {
+  override fun sizeOrderedList(): List<String> {
     val wrappedFileList = mutableListOf<WrappedFile>()
     musicList.forEach { wrappedFileList.add(WrappedFile(File(it))) }
     wrappedFileList.sortBy { it.size }
@@ -50,7 +50,7 @@ class MusicLister : Lister() {
     return result
   }
 
-  fun getFullSize(): ULong {
+  override fun getFullSize(): ULong {
     var size = 0UL
     val wrappedFileList = mutableListOf<WrappedFile>()
     musicList.forEach { wrappedFileList.add(WrappedFile(File(it))) }
diff --git a/app/src/main/java/com/example/myapplication/fileSystem/byTypeFileLister/VideoLister.kt b/app/src/main/java/com/example/myapplication/fileSystem/byTypeFileLister/VideoLister.kt
index 5e97380..acb204a 100644
--- a/app/src/main/java/com/example/myapplication/fileSystem/byTypeFileLister/VideoLister.kt
+++ b/app/src/main/java/com/example/myapplication/fileSystem/byTypeFileLister/VideoLister.kt
@@ -7,11 +7,11 @@ import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
 import java.io.File
 
-class VideoLister : Lister() {
+class VideoLister : Lister {
   companion object {
     val instance by lazy { VideoLister() }
     val directories = listOf("DCIM", "Download", "Movies")
-    val regex = "\\.(mp4|avi|video|webm)".toRegex()
+    val regex = "\\.(mp4|avi|video|webm)$".toRegex()
   }
 
   val videoList = mutableListOf<String>()
@@ -31,7 +31,7 @@ class VideoLister : Lister() {
     return
   }
 
-  fun dateOrderedList(): List<String> {
+  override fun dateOrderedList(): List<String> {
     val wrappedFileList = mutableListOf<WrappedFile>()
     videoList.forEach { wrappedFileList.add(WrappedFile(File(it))) }
     wrappedFileList.sortBy { it.lastModifiedTime }
@@ -40,7 +40,7 @@ class VideoLister : Lister() {
     return result
   }
 
-  fun sizeOrderedList(): List<String> {
+  override fun sizeOrderedList(): List<String> {
     val wrappedFileList = mutableListOf<WrappedFile>()
     videoList.forEach { wrappedFileList.add(WrappedFile(File(it))) }
     wrappedFileList.sortBy { it.size }
@@ -49,7 +49,7 @@ class VideoLister : Lister() {
     return result
   }
 
-  fun getFullSize(): ULong {
+  override fun getFullSize(): ULong {
     var size = 0UL
     val wrappedFileList = mutableListOf<WrappedFile>()
     videoList.forEach { wrappedFileList.add(WrappedFile(File(it))) }
diff --git a/app/src/main/java/com/example/myapplication/fileSystem/byTypeFileLister/Walker.kt b/app/src/main/java/com/example/myapplication/fileSystem/byTypeFileLister/Walker.kt
deleted file mode 100644
index 988eb25..0000000
--- a/app/src/main/java/com/example/myapplication/fileSystem/byTypeFileLister/Walker.kt
+++ /dev/null
@@ -1,25 +0,0 @@
-package com.example.myapplication.fileSystem.byTypeFileLister
-
-import java.io.File
-
-fun Lister.walkDir(
-  directory: File,
-  list: MutableList<String>,
-  pattern: Regex,
-  ignoreDotFile: Boolean = true
-) {
-  if (!directory.exists() || !directory.isDirectory) {
-    return
-  }
-  directory.listFiles()?.forEach {
-    if (ignoreDotFile && !it.name.startsWith(".")) {
-      if (it.isDirectory) {
-        walkDir(it, list, pattern)
-      } else if (it.isFile) {
-        if (it.name.contains(pattern)) {
-          list.add(it.path)
-        }
-      }
-    }
-  }
-}
\ No newline at end of file