diff --git a/app/src/main/java/com/android/grape/sai/ApkSourceBuilder.kt b/app/src/main/java/com/android/grape/sai/ApkSourceBuilder.kt
index ae9e2a4..4e1ae00 100644
--- a/app/src/main/java/com/android/grape/sai/ApkSourceBuilder.kt
+++ b/app/src/main/java/com/android/grape/sai/ApkSourceBuilder.kt
@@ -83,7 +83,9 @@ class ApkSourceBuilder(private val mContext: Context) {
             val apkFileDescriptors: MutableList<FileDescriptor> = ArrayList<FileDescriptor>(
                 mApkFiles?.size?: 0
             )
-            for (apkFile in mApkFiles!!) apkFileDescriptors.add(NormalFileDescriptor(apkFile))
+            mApkFiles?.let {
+                for (apkFile in it) apkFileDescriptors.add(NormalFileDescriptor(apkFile))
+            }
 
             apkSource = DefaultApkSource(apkFileDescriptors)
         } else if (mZipFile != null) {
diff --git a/app/src/main/java/com/android/grape/sai/FlexSaiPackageInstaller.kt b/app/src/main/java/com/android/grape/sai/FlexSaiPackageInstaller.kt
index 6d49020..5fc9b78 100644
--- a/app/src/main/java/com/android/grape/sai/FlexSaiPackageInstaller.kt
+++ b/app/src/main/java/com/android/grape/sai/FlexSaiPackageInstaller.kt
@@ -59,13 +59,16 @@ class FlexSaiPackageInstaller private constructor(c: Context) : SaiPackageInstal
         installer: SaiPackageInstaller,
         params: SaiPiSessionParams
     ): String {
-        val sessionId = installer.createSession(params)
-        mSessionIdToInstaller[sessionId!!] = installer
+        val sessionId = installer.createSession(params)?:""
+        mSessionIdToInstaller[sessionId] = installer
         return sessionId
     }
 
     override fun createSession(params: SaiPiSessionParams): String {
-        return createSessionOnInstaller(mDefaultInstaller!!, params)
+        mDefaultInstaller?.let {
+            return createSessionOnInstaller(it, params)
+        }
+        return  ""
     }
 
     override fun enqueueSession(sessionId: String) {
diff --git a/app/src/main/java/com/android/grape/sai/MyBroadcastReceiver.kt b/app/src/main/java/com/android/grape/sai/MyBroadcastReceiver.kt
index 3151fc6..304456b 100644
--- a/app/src/main/java/com/android/grape/sai/MyBroadcastReceiver.kt
+++ b/app/src/main/java/com/android/grape/sai/MyBroadcastReceiver.kt
@@ -18,7 +18,7 @@ class MyBroadcastReceiver : BroadcastReceiver() {
         //接收广播消息
         fruit = intent.getStringExtra("fruit")
         //调用接口MyReceiver里面的interFruit方法传入接收的内容
-        mReceiver!!.interFruit(fruit)
+        mReceiver?.interFruit(fruit)
         //使用Toast显示广播消息
         Toast.makeText(context, fruit, Toast.LENGTH_SHORT).show()
     }
diff --git a/app/src/main/java/com/android/grape/sai/RootlessSaiPiBroadcastReceiver.kt b/app/src/main/java/com/android/grape/sai/RootlessSaiPiBroadcastReceiver.kt
index f9db119..e5ae184 100644
--- a/app/src/main/java/com/android/grape/sai/RootlessSaiPiBroadcastReceiver.kt
+++ b/app/src/main/java/com/android/grape/sai/RootlessSaiPiBroadcastReceiver.kt
@@ -116,7 +116,7 @@ class RootlessSaiPiBroadcastReceiver(c: Context) : BroadcastReceiver() {
 
         val androidPackageInstallerError: AndroidPackageInstallerError =
             getAndroidPmError(errorCode, error)
-        if (androidPackageInstallerError !== AndroidPackageInstallerError.UNKNOWN) {
+        if (androidPackageInstallerError != AndroidPackageInstallerError.UNKNOWN) {
             return androidPackageInstallerError.getDescription(mContext)
         }
 
diff --git a/app/src/main/java/com/android/grape/sai/ShellSaiPackageInstaller.kt b/app/src/main/java/com/android/grape/sai/ShellSaiPackageInstaller.kt
index b02dba9..3968784 100644
--- a/app/src/main/java/com/android/grape/sai/ShellSaiPackageInstaller.kt
+++ b/app/src/main/java/com/android/grape/sai/ShellSaiPackageInstaller.kt
@@ -53,9 +53,9 @@ abstract class ShellSaiPackageInstaller protected constructor(c: Context?) :
 
                 val installedPackage: String
                 try {
-                    installedPackage = intent.dataString!!.replace("package:", "")
+                    installedPackage = intent.dataString?.replace("package:", "")?:""
                     val installerPackage: String =
-                        context.getPackageManager().getInstallerPackageName(installedPackage)?:""
+                        context.packageManager.getInstallerPackageName(installedPackage)?:""
                     Log.d(tag(), "installerPackage=$installerPackage")
                     if ("com.android.grape" != installerPackage) return
                 } catch (e: Exception) {
@@ -135,6 +135,7 @@ abstract class ShellSaiPackageInstaller protected constructor(c: Context?) :
                     return
                 }
                 androidSessionId = createSession()
+                //todo params.apkSource().apkLocalPath?
                 val path = "/sdcard/apks/" + "com.zhiliaoapp.musically"
                 val file = File(path)
 
diff --git a/app/src/main/java/com/android/grape/sai/apksource/CopyToFileApkSource.kt b/app/src/main/java/com/android/grape/sai/apksource/CopyToFileApkSource.kt
index 7800bb0..6ebf0b3 100644
--- a/app/src/main/java/com/android/grape/sai/apksource/CopyToFileApkSource.kt
+++ b/app/src/main/java/com/android/grape/sai/apksource/CopyToFileApkSource.kt
@@ -28,7 +28,7 @@ class CopyToFileApkSource(context: Context, wrappedApkSource: ApkSource) :
             IOUtils.deleteRecursively(it)
         }
 
-        mCurrentApkFile = File(mTempDir, mWrappedApkSource.apkName)
+        mCurrentApkFile = File(mTempDir, mWrappedApkSource.apkName?:"")
 
         mWrappedApkSource.openApkInputStream().use { `in` ->
             FileOutputStream(mCurrentApkFile).use { out ->
diff --git a/app/src/main/java/com/android/grape/sai/apksource/SignerApkSource.kt b/app/src/main/java/com/android/grape/sai/apksource/SignerApkSource.kt
index c51b2dd..3ea0b28 100644
--- a/app/src/main/java/com/android/grape/sai/apksource/SignerApkSource.kt
+++ b/app/src/main/java/com/android/grape/sai/apksource/SignerApkSource.kt
@@ -34,7 +34,7 @@ class SignerApkSource(private val mContext: Context, apkSource: ApkSource) : Apk
             )
         }
 
-        mCurrentSignedApkFile = File(mTempDir, apkName)
+        mCurrentSignedApkFile = File(mTempDir, apkName?:"")
         mWrappedApkSource.openApkInputStream()?.let {
             mApkSigner?.sign(
                 it,
diff --git a/app/src/main/java/com/android/grape/sai/filedescriptor/FileUtils.kt b/app/src/main/java/com/android/grape/sai/filedescriptor/FileUtils.kt
index 67b6392..7e7ec7c 100644
--- a/app/src/main/java/com/android/grape/sai/filedescriptor/FileUtils.kt
+++ b/app/src/main/java/com/android/grape/sai/filedescriptor/FileUtils.kt
@@ -38,11 +38,11 @@ object FileUtils {
     }
 
     private fun trimFilename(res: StringBuilder, maxBytes: Int) {
-        var maxBytes = maxBytes
+        var bytes = maxBytes
         var raw = res.toString().toByteArray(StandardCharsets.UTF_8)
-        if (raw.size > maxBytes) {
-            maxBytes -= 3
-            while (raw.size > maxBytes) {
+        if (raw.size > bytes) {
+            bytes -= 3
+            while (raw.size > bytes) {
                 res.deleteCharAt(res.length / 2)
                 raw = res.toString().toByteArray(StandardCharsets.UTF_8)
             }
diff --git a/app/src/main/java/com/android/grape/sai/filedescriptor/ZipApkSource.kt b/app/src/main/java/com/android/grape/sai/filedescriptor/ZipApkSource.kt
index 3de5820..87d7167 100644
--- a/app/src/main/java/com/android/grape/sai/filedescriptor/ZipApkSource.kt
+++ b/app/src/main/java/com/android/grape/sai/filedescriptor/ZipApkSource.kt
@@ -25,14 +25,15 @@ class ZipApkSource(private val mContext: Context, private val mZipFileDescriptor
     @Throws(Exception::class)
     override fun nextApk(): Boolean {
         if (!mIsOpen) {
-            mZipInputStream = ZipInputStream(mZipFileDescriptor.open())
-            mWrappedStream = ZipInputStreamWrapper(mZipInputStream!!)
+            mZipInputStream = ZipInputStream(mZipFileDescriptor.open()).apply {
+                mWrappedStream = ZipInputStreamWrapper(this)
+            }
             mIsOpen = true
         }
 
         do {
             try {
-                entry = mZipInputStream!!.nextEntry
+                entry = mZipInputStream?.nextEntry
             } catch (e: ZipException) {
                 if (e.message == "only DEFLATED entries can have EXT descriptor") {
                     throw ZipException("only DEFLATED entries can have EXT descriptor")
diff --git a/app/src/main/java/com/android/grape/sai/filedescriptor/ZipFileApkSource.kt b/app/src/main/java/com/android/grape/sai/filedescriptor/ZipFileApkSource.kt
index 6642a3b..fe077a0 100644
--- a/app/src/main/java/com/android/grape/sai/filedescriptor/ZipFileApkSource.kt
+++ b/app/src/main/java/com/android/grape/sai/filedescriptor/ZipFileApkSource.kt
@@ -35,13 +35,14 @@ class ZipFileApkSource(context: Context, private val mZipFileDescriptor: FileDes
         if (mZipFile == null) copyAndOpenZip()
 
         entry = null
-        while (entry == null && mZipEntries!!.hasMoreElements()) {
-            val nextEntry = mZipEntries!!.nextElement()
-            if (!nextEntry.isDirectory && nextEntry.name.lowercase(Locale.getDefault())
-                    .endsWith(".apk")
-            ) {
-                entry = nextEntry
-                mSeenApkFile = true
+        while (entry == null && mZipEntries?.hasMoreElements() == true) {
+            mZipEntries?.nextElement()?.let { nextEntry ->
+                if (!nextEntry.isDirectory && nextEntry.name.lowercase(Locale.getDefault())
+                        .endsWith(".apk")
+                ) {
+                    entry = nextEntry
+                    mSeenApkFile = true
+                }
             }
         }
 
diff --git a/app/src/main/java/com/android/grape/sai/param/PackageMeta.kt b/app/src/main/java/com/android/grape/sai/param/PackageMeta.kt
index 1c638fb..16d355f 100644
--- a/app/src/main/java/com/android/grape/sai/param/PackageMeta.kt
+++ b/app/src/main/java/com/android/grape/sai/param/PackageMeta.kt
@@ -138,7 +138,7 @@ class PackageMeta : Parcelable {
 
                 return Builder(applicationInfo.packageName)
                     .setLabel(applicationInfo.loadLabel(pm).toString())
-                    .setHasSplits(applicationInfo.splitPublicSourceDirs != null && applicationInfo.splitPublicSourceDirs!!.size > 0)
+                    .setHasSplits(applicationInfo.splitPublicSourceDirs != null && applicationInfo.splitPublicSourceDirs?.isNotEmpty() == true)
                     .setIsSystemApp((applicationInfo.flags and ApplicationInfo.FLAG_SYSTEM) != 0)
                     .setVersionCode(if (Utils.apiIsAtLeast(Build.VERSION_CODES.P)) packageInfo.longVersionCode else packageInfo.versionCode.toLong())
                     .setVersionName(packageInfo.versionName)
diff --git a/app/src/main/java/com/android/grape/sai/param/SaiPiSessionState.kt b/app/src/main/java/com/android/grape/sai/param/SaiPiSessionState.kt
index a4113d7..88f165f 100644
--- a/app/src/main/java/com/android/grape/sai/param/SaiPiSessionState.kt
+++ b/app/src/main/java/com/android/grape/sai/param/SaiPiSessionState.kt
@@ -127,11 +127,11 @@ class SaiPiSessionState private constructor(
         }
 
         fun error(shortError: String?, fullError: String?): Builder {
-            var fullError = fullError
+            var error = fullError
             mState.mShortError = shortError
-            if (fullError == null) fullError = shortError
+            if (error == null) error = shortError
 
-            mState.mFullError = fullError
+            mState.mFullError = error
             return this
         }
 
diff --git a/app/src/main/java/com/android/grape/sai/prefers/PreferencesHelper.kt b/app/src/main/java/com/android/grape/sai/prefers/PreferencesHelper.kt
index 7345354..753e084 100644
--- a/app/src/main/java/com/android/grape/sai/prefers/PreferencesHelper.kt
+++ b/app/src/main/java/com/android/grape/sai/prefers/PreferencesHelper.kt
@@ -3,6 +3,7 @@ package com.android.grape.sai.prefers
 import android.content.Context
 import android.content.SharedPreferences
 import android.os.Environment
+import androidx.core.content.edit
 
 
 class PreferencesHelper private constructor(c: Context) {
@@ -50,7 +51,7 @@ class PreferencesHelper private constructor(c: Context) {
     }
 
     fun setShouldSignApks(signApks: Boolean) {
-        prefs.edit().putBoolean(PreferencesKeys.SIGN_APKS, signApks).apply()
+        prefs.edit { putBoolean(PreferencesKeys.SIGN_APKS, signApks) }
     }
 
     fun shouldExtractArchives(): Boolean {
@@ -64,7 +65,7 @@ class PreferencesHelper private constructor(c: Context) {
     var installer: Int
         get() = prefs.getInt(PreferencesKeys.INSTALLER, PreferencesValues.INSTALLER_ROOTED)
         set(installer) {
-            prefs.edit().putInt(PreferencesKeys.INSTALLER, installer).apply()
+            prefs.edit { putInt(PreferencesKeys.INSTALLER, installer) }
         }
 
     var backupFileNameFormat: String?
@@ -73,7 +74,7 @@ class PreferencesHelper private constructor(c: Context) {
             PreferencesValues.BACKUP_FILE_NAME_FORMAT_DEFAULT
         )
         set(format) {
-            prefs.edit().putString(PreferencesKeys.BACKUP_FILE_NAME_FORMAT, format).apply()
+            prefs.edit { putString(PreferencesKeys.BACKUP_FILE_NAME_FORMAT, format) }
         }
 
     var installLocation: Int
@@ -87,8 +88,9 @@ class PreferencesHelper private constructor(c: Context) {
             }
         }
         set(installLocation) {
-            prefs.edit().putString(PreferencesKeys.INSTALL_LOCATION, installLocation.toString())
-                .apply()
+            prefs.edit {
+                putString(PreferencesKeys.INSTALL_LOCATION, installLocation.toString())
+            }
         }
 
     fun useOldInstaller(): Boolean {
@@ -108,7 +110,7 @@ class PreferencesHelper private constructor(c: Context) {
     }
 
     fun setSafTipShown() {
-        prefs.edit().putBoolean(PreferencesKeys.SAF_TIP_SHOWN, true).apply()
+        prefs.edit { putBoolean(PreferencesKeys.SAF_TIP_SHOWN, true) }
     }
 
     val isInstallerXEnabled: Boolean
@@ -120,19 +122,19 @@ class PreferencesHelper private constructor(c: Context) {
     var isAnalyticsEnabled: Boolean
         get() = prefs.getBoolean(PreferencesKeys.ENABLE_ANALYTICS, true)
         set(enabled) {
-            prefs.edit().putBoolean(PreferencesKeys.ENABLE_ANALYTICS, enabled).apply()
+            prefs.edit { putBoolean(PreferencesKeys.ENABLE_ANALYTICS, enabled) }
         }
 
     var isInitialIndexingDone: Boolean
         get() = prefs.getBoolean(PreferencesKeys.INITIAL_INDEXING_RUN, false)
         set(done) {
-            prefs.edit().putBoolean(PreferencesKeys.INITIAL_INDEXING_RUN, done).apply()
+            prefs.edit { putBoolean(PreferencesKeys.INITIAL_INDEXING_RUN, done) }
         }
 
     var isSingleApkExportEnabled: Boolean
         get() = prefs.getBoolean(PreferencesKeys.BACKUP_APK_EXPORT, false)
         set(enabled) {
-            prefs.edit().putBoolean(PreferencesKeys.BACKUP_APK_EXPORT, enabled).apply()
+            prefs.edit { putBoolean(PreferencesKeys.BACKUP_APK_EXPORT, enabled) }
         }
 
     companion object {
diff --git a/app/src/main/java/com/android/grape/service/MyAccessibilityService.kt b/app/src/main/java/com/android/grape/service/MyAccessibilityService.kt
index 77dc64a..6b63810 100644
--- a/app/src/main/java/com/android/grape/service/MyAccessibilityService.kt
+++ b/app/src/main/java/com/android/grape/service/MyAccessibilityService.kt
@@ -40,9 +40,7 @@ class MyAccessibilityService:AccessibilityService(){
             val manager: NotificationManager = getSystemService<NotificationManager>(
                 NotificationManager::class.java
             )
-            if (manager != null) {
-                manager.createNotificationChannel(channel)
-            }
+            manager.createNotificationChannel(channel)
         }
     }
 
diff --git a/app/src/main/java/com/android/grape/util/Util.kt b/app/src/main/java/com/android/grape/util/Util.kt
index ee74d60..66d0e70 100644
--- a/app/src/main/java/com/android/grape/util/Util.kt
+++ b/app/src/main/java/com/android/grape/util/Util.kt
@@ -275,10 +275,7 @@ object Util {
     }
 
     fun isInstallRet(): Boolean {
-        if (installRet == null) {
-            return false
-        }
-        return installRet!!
+        return installRet?:false
     }
 
     fun setAfLog(afLogV: String) {
diff --git a/app/src/main/java/com/android/grape/work/CheckAccessibilityWorker.kt b/app/src/main/java/com/android/grape/work/CheckAccessibilityWorker.kt
index 65ec54b..81cdda9 100644
--- a/app/src/main/java/com/android/grape/work/CheckAccessibilityWorker.kt
+++ b/app/src/main/java/com/android/grape/work/CheckAccessibilityWorker.kt
@@ -9,6 +9,7 @@ import android.text.TextUtils
 import androidx.work.CoroutineWorker
 import androidx.work.WorkerParameters
 import com.android.grape.service.MyAccessibilityService
+import androidx.core.content.edit
 
 class CheckAccessibilityWorker(
     context: Context,
@@ -32,7 +33,7 @@ class CheckAccessibilityWorker(
                 applicationContext.startActivity(intent)
 
                 // 更新状态
-                sharedPreferences.edit().putBoolean("accessibility_prompted", true).apply()
+                sharedPreferences.edit { putBoolean("accessibility_prompted", true) }
             }
             return Result.retry()
         }