diff --git a/app/src/main/java/io/legado/app/data/entities/BookSource.kt b/app/src/main/java/io/legado/app/data/entities/BookSource.kt
index a8a88e4cb..d2a61e330 100644
--- a/app/src/main/java/io/legado/app/data/entities/BookSource.kt
+++ b/app/src/main/java/io/legado/app/data/entities/BookSource.kt
@@ -126,7 +126,7 @@ data class BookSource(
                 try {
                     if (it.startsWith("<js>", false)) {
                         val aCache = ACache.get(App.INSTANCE, "explore")
-                        a = aCache.getAsString(bookSourceUrl) ?: ""
+                        a = aCache?.getAsString(bookSourceUrl) ?: ""
                         if (a.isBlank()) {
                             val bindings = SimpleBindings()
                             bindings["baseUrl"] = bookSourceUrl
@@ -135,7 +135,7 @@ data class BookSource(
                                 it.substring(4, it.lastIndexOf("<")),
                                 bindings
                             ).toString()
-                            aCache.put(bookSourceUrl, a)
+                            aCache?.put(bookSourceUrl, a)
                         }
                     }
                     val b = a.split("(&&|\n)+".toRegex())
diff --git a/app/src/main/java/io/legado/app/ui/main/explore/ExploreAdapter.kt b/app/src/main/java/io/legado/app/ui/main/explore/ExploreAdapter.kt
index 0bc6c0891..136d7d4bf 100644
--- a/app/src/main/java/io/legado/app/ui/main/explore/ExploreAdapter.kt
+++ b/app/src/main/java/io/legado/app/ui/main/explore/ExploreAdapter.kt
@@ -48,7 +48,7 @@ class ExploreAdapter(context: Context, private val scope: CoroutineScope, val ca
                             R.id.menu_edit -> callBack.editSource(item.bookSourceUrl)
                             R.id.menu_top -> callBack.toTop(item)
                             R.id.menu_refresh -> {
-                                ACache.get(context, "explore").remove(item.bookSourceUrl)
+                                ACache.get(context, "explore")?.remove(item.bookSourceUrl)
                                 notifyItemChanged(holder.layoutPosition)
                             }
                         }
diff --git a/app/src/main/java/io/legado/app/utils/ACache.kt b/app/src/main/java/io/legado/app/utils/ACache.kt
index 049b623da..c9b2fda3d 100644
--- a/app/src/main/java/io/legado/app/utils/ACache.kt
+++ b/app/src/main/java/io/legado/app/utils/ACache.kt
@@ -336,7 +336,7 @@ class ACache private constructor(cacheDir: File, max_size: Long, max_count: Int)
      * @param value 保存的bitmap数据
      */
     fun put(key: String, value: Bitmap) {
-        put(key, Utils.Bitmap2Bytes(value))
+        put(key, Utils.bitmap2Bytes(value))
     }
 
     /**
@@ -347,7 +347,7 @@ class ACache private constructor(cacheDir: File, max_size: Long, max_count: Int)
      * @param saveTime 保存的时间，单位：秒
      */
     fun put(key: String, value: Bitmap, saveTime: Int) {
-        put(key, Utils.Bitmap2Bytes(value), saveTime)
+        put(key, Utils.bitmap2Bytes(value), saveTime)
     }
 
     /**
@@ -358,7 +358,7 @@ class ACache private constructor(cacheDir: File, max_size: Long, max_count: Int)
     fun getAsBitmap(key: String): Bitmap? {
         return if (getAsBinary(key) == null) {
             null
-        } else Utils.Bytes2Bimap(getAsBinary(key)!!)
+        } else Utils.bytes2Bitmap(getAsBinary(key)!!)
     }
 
     // =======================================
@@ -395,7 +395,7 @@ class ACache private constructor(cacheDir: File, max_size: Long, max_count: Int)
         return if (getAsBinary(key) == null) {
             null
         } else Utils.bitmap2Drawable(
-            Utils.Bytes2Bimap(
+            Utils.bytes2Bitmap(
                 getAsBinary(key)!!
             )
         )
@@ -486,16 +486,17 @@ class ACache private constructor(cacheDir: File, max_size: Long, max_count: Int)
 
         fun newByteArrayWithDateInfo(second: Int, data2: ByteArray): ByteArray {
             val data1 = createDateInfo(second).toByteArray()
-            val retdata = ByteArray(data1.size + data2.size)
-            System.arraycopy(data1, 0, retdata, 0, data1.size)
-            System.arraycopy(data2, 0, retdata, data1.size, data2.size)
-            return retdata
+            val retData = ByteArray(data1.size + data2.size)
+            System.arraycopy(data1, 0, retData, 0, data1.size)
+            System.arraycopy(data2, 0, retData, data1.size, data2.size)
+            return retData
         }
 
         fun clearDateInfo(strInfo: String?): String? {
-            var strInfo = strInfo
-            if (strInfo != null && hasDateInfo(strInfo.toByteArray())) {
-                strInfo = strInfo.substring(strInfo.indexOf(mSeparator) + 1)
+            strInfo?.let {
+                if (hasDateInfo(strInfo.toByteArray())) {
+                    return strInfo.substring(strInfo.indexOf(mSeparator) + 1)
+                }
             }
             return strInfo
         }
@@ -559,7 +560,7 @@ class ACache private constructor(cacheDir: File, max_size: Long, max_count: Int)
         /*
          * Bitmap → byte[]
          */
-        fun Bitmap2Bytes(bm: Bitmap): ByteArray {
+        fun bitmap2Bytes(bm: Bitmap): ByteArray {
             val baos = ByteArrayOutputStream()
             bm.compress(Bitmap.CompressFormat.PNG, 100, baos)
             return baos.toByteArray()
@@ -568,8 +569,8 @@ class ACache private constructor(cacheDir: File, max_size: Long, max_count: Int)
         /*
          * byte[] → Bitmap
          */
-        fun Bytes2Bimap(b: ByteArray): Bitmap? {
-            return if (b.size == 0) {
+        fun bytes2Bitmap(b: ByteArray): Bitmap? {
+            return if (b.isEmpty()) {
                 null
             } else BitmapFactory.decodeByteArray(b, 0, b.size)
         }