diff --git a/app/src/main/java/io/legado/app/lib/icu4j/CharsetDetector.java b/app/src/main/java/io/legado/app/lib/icu4j/CharsetDetector.java
index 8d35b65a1..8432cb005 100644
--- a/app/src/main/java/io/legado/app/lib/icu4j/CharsetDetector.java
+++ b/app/src/main/java/io/legado/app/lib/icu4j/CharsetDetector.java
@@ -8,6 +8,8 @@
  */
 package io.legado.app.lib.icu4j;
 
+import androidx.annotation.Nullable;
+
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.Reader;
@@ -150,6 +152,7 @@ public class CharsetDetector {
      * <code>null</code> if there are no matches.
      * @stable ICU 3.4
      */
+    @Nullable
     public CharsetMatch detect() {
 //   TODO:  A better implementation would be to copy the detect loop from
 //          detectAll(), and cut it short as soon as a match with a high confidence
diff --git a/app/src/main/java/io/legado/app/utils/EncodingDetect.kt b/app/src/main/java/io/legado/app/utils/EncodingDetect.kt
index de698c8e0..83f659fa9 100644
--- a/app/src/main/java/io/legado/app/utils/EncodingDetect.kt
+++ b/app/src/main/java/io/legado/app/utils/EncodingDetect.kt
@@ -46,10 +46,8 @@ object EncodingDetect {
     }
 
     fun getEncode(bytes: ByteArray): String {
-        val detector = CharsetDetector()
-        detector.setText(bytes)
-        val match = detector.detect()
-        return match.name
+        val match = CharsetDetector().setText(bytes).detect()
+        return match?.name ?: "UTF-8"
     }
 
     /**
@@ -67,13 +65,12 @@ object EncodingDetect {
         return getEncode(tempByte)
     }
 
-    private fun getFileBytes(testFile: File?): ByteArray {
-        val fis: FileInputStream
-        val byteArray = ByteArray(2000)
+    private fun getFileBytes(file: File?): ByteArray {
+        val byteArray = ByteArray(8000)
         try {
-            fis = FileInputStream(testFile)
-            fis.read(byteArray)
-            fis.close()
+            FileInputStream(file).use {
+                it.read(byteArray)
+            }
         } catch (e: Exception) {
             System.err.println("Error: $e")
         }