diff --git a/app/src/main/java/com/hippo/ehviewer/spider/SpiderDen.kt b/app/src/main/java/com/hippo/ehviewer/spider/SpiderDen.kt
index 72039b7db..9c3e10700 100644
--- a/app/src/main/java/com/hippo/ehviewer/spider/SpiderDen.kt
+++ b/app/src/main/java/com/hippo/ehviewer/spider/SpiderDen.kt
@@ -32,7 +32,6 @@ import com.hippo.unifile.RawFile
 import com.hippo.unifile.UniFile
 import com.hippo.yorozuya.FileUtils
 import com.hippo.yorozuya.MathUtils
-import com.hippo.yorozuya.Utilities
 import io.ktor.client.plugins.onDownload
 import io.ktor.client.request.prepareGet
 import io.ktor.client.statement.HttpResponse
@@ -103,15 +102,8 @@ class SpiderDen(private val mGalleryInfo: GalleryInfo) {
      * @param extension with dot
      */
     private fun fixExtension(extension: String): String {
-        return if (Utilities.contain(
-                PageLoader2.SUPPORT_IMAGE_EXTENSIONS,
-                extension
-            )
-        ) {
-            extension
-        } else {
-            PageLoader2.SUPPORT_IMAGE_EXTENSIONS[0]
-        }
+        return extension.takeIf { PageLoader2.SUPPORT_IMAGE_EXTENSIONS.contains(it) }
+            ?: PageLoader2.SUPPORT_IMAGE_EXTENSIONS[0]
     }
 
     private fun copyFromCacheToDownloadDir(index: Int): Boolean {
@@ -158,19 +150,7 @@ class SpiderDen(private val mGalleryInfo: GalleryInfo) {
     }
 
     private fun removeFromDownloadDir(index: Int): Boolean {
-        val dir = downloadDir ?: return false
-        var result = false
-        var i = 0
-        val n = PageLoader2.SUPPORT_IMAGE_EXTENSIONS.size
-        while (i < n) {
-            val filename = generateImageFilename(index, PageLoader2.SUPPORT_IMAGE_EXTENSIONS[i])
-            val file = dir.subFile(filename)
-            if (file != null) {
-                result = result or runCatching { file.delete() }.getOrDefault(false)
-            }
-            i++
-        }
-        return result
+        return downloadDir?.let { findImageFile(it, index)?.delete() } ?: false
     }
 
     fun remove(index: Int): Boolean {
@@ -290,7 +270,8 @@ class SpiderDen(private val mGalleryInfo: GalleryInfo) {
     fun getExtension(index: Int): String? {
         val key = EhCacheKeyFactory.getImageKey(mGid, index)
         return sCache[key]?.use { it.metadata.toNioPath().readText() }
-            ?: downloadDir?.let { findImageFile(it, index) }?.name.let { FileUtils.getExtensionFromFilename(it) }
+            ?: downloadDir?.let { findImageFile(it, index) }
+                ?.name.let { FileUtils.getExtensionFromFilename(it) }
     }
 
     fun getImageSource(index: Int): ByteBufferSource? {
diff --git a/app/src/main/java/com/hippo/unifile/DocumentsContractApi19.java b/app/src/main/java/com/hippo/unifile/DocumentsContractApi19.java
index 4a2747fbf..ae3dc4914 100644
--- a/app/src/main/java/com/hippo/unifile/DocumentsContractApi19.java
+++ b/app/src/main/java/com/hippo/unifile/DocumentsContractApi19.java
@@ -16,21 +16,16 @@
 
 package com.hippo.unifile;
 
-import android.annotation.TargetApi;
 import android.content.ContentResolver;
 import android.content.Context;
 import android.content.Intent;
 import android.content.pm.PackageManager;
 import android.database.Cursor;
 import android.net.Uri;
-import android.os.Build;
 import android.provider.DocumentsContract;
 import android.text.TextUtils;
-import android.util.Log;
 
-@TargetApi(Build.VERSION_CODES.KITKAT)
 final class DocumentsContractApi19 {
-    private static final String TAG = DocumentsContractApi19.class.getSimpleName();
 
     private DocumentsContractApi19() {
     }
@@ -118,8 +113,6 @@ final class DocumentsContractApi19 {
             return DocumentsContract.deleteDocument(context.getContentResolver(), self);
         } catch (Throwable e) {
             Utils.throwIfFatal(e);
-            // Maybe user ejects tf card
-            Log.e(TAG, "Failed to renameTo", e);
             return false;
         }
     }
@@ -134,7 +127,6 @@ final class DocumentsContractApi19 {
             return null != c && c.getCount() > 0;
         } catch (Throwable e) {
             Utils.throwIfFatal(e);
-            // Log.w(TAG, "Failed query: " + e);
             return false;
         } finally {
             Utils.closeQuietly(c);
diff --git a/app/src/main/java/com/hippo/unifile/DocumentsContractApi21.java b/app/src/main/java/com/hippo/unifile/DocumentsContractApi21.java
index a0c805183..60ed7a3a9 100644
--- a/app/src/main/java/com/hippo/unifile/DocumentsContractApi21.java
+++ b/app/src/main/java/com/hippo/unifile/DocumentsContractApi21.java
@@ -16,21 +16,16 @@
 
 package com.hippo.unifile;
 
-import android.annotation.TargetApi;
 import android.content.ContentResolver;
 import android.content.Context;
 import android.database.Cursor;
 import android.net.Uri;
-import android.os.Build;
 import android.provider.DocumentsContract;
-import android.util.Log;
 
 import java.util.ArrayList;
 import java.util.List;
 
-@TargetApi(Build.VERSION_CODES.LOLLIPOP)
 final class DocumentsContractApi21 {
-    private static final String TAG = DocumentsContractApi21.class.getSimpleName();
     private static final String PATH_DOCUMENT = "document";
     private static final String PATH_TREE = "tree";
 
@@ -44,8 +39,6 @@ final class DocumentsContractApi21 {
                     displayName);
         } catch (Throwable e) {
             Utils.throwIfFatal(e);
-            // Maybe user ejects tf card
-            Log.e(TAG, "Failed to createFile: " + self, e);
             return null;
         }
     }
@@ -92,12 +85,11 @@ final class DocumentsContractApi21 {
             }
         } catch (Throwable e) {
             Utils.throwIfFatal(e);
-            Log.e(TAG, "Failed listFiles: " + self, e);
         } finally {
             Utils.closeQuietly(c);
         }
 
-        return results.toArray(new Uri[results.size()]);
+        return results.toArray(new Uri[0]);
     }
 
     public static Uri renameTo(Context context, Uri self, String displayName) {
@@ -105,8 +97,6 @@ final class DocumentsContractApi21 {
             return DocumentsContract.renameDocument(context.getContentResolver(), self, displayName);
         } catch (Throwable e) {
             Utils.throwIfFatal(e);
-            // Maybe user ejects tf card
-            Log.e(TAG, "Failed to renameTo:" + self + ", " + displayName, e);
             return null;
         }
     }