Remove compatibility code for Jelly Bean

src/main/scala/com/github/shadowsocks/Shadowsocks.scala

@@ -500,11 +500,8 @@ class Shadowsocks extends AppCompatActivity with ServiceBoundContext {
     clearDialog()
   }
 
-  private var _isDestroyed: Boolean = _
-  override def isDestroyed = if (Build.VERSION.SDK_INT >= 17) super.isDestroyed else _isDestroyed
   override def onDestroy() {
     super.onDestroy()
-    _isDestroyed = true
     detachService()
     new BackupManager(this).dataChanged()
     handler.removeCallbacksAndMessages(null)

src/main/scala/com/github/shadowsocks/ShadowsocksSettings.scala

@@ -5,7 +5,7 @@ import java.util.Locale
 import android.content.SharedPreferences.OnSharedPreferenceChangeListener
 import android.content.{Intent, SharedPreferences}
 import android.net.Uri
-import android.os.{Build, Bundle}
+import android.os.Bundle
 import android.preference.{Preference, PreferenceFragment, SwitchPreference}
 import android.support.v7.app.AlertDialog
 import android.webkit.{WebView, WebViewClient}
@@ -160,9 +160,7 @@ class ShadowsocksSettings extends PreferenceFragment with OnSharedPreferenceChan
       true
     })
 
-    val flush = findPreference("flush_dnscache")
-    if (Build.VERSION.SDK_INT < 17) flush.setSummary(R.string.flush_dnscache_summary)
-    flush.setOnPreferenceClickListener(_ => {
+    findPreference("flush_dnscache").setOnPreferenceClickListener(_ => {
       app.track(TAG, "flush_dnscache")
       activity.flushDnsCache()
       true

src/main/scala/com/github/shadowsocks/utils/Utils.scala

@@ -46,7 +46,6 @@ import android.content.pm.PackageManager
 import android.content.{Context, Intent}
 import android.graphics._
 import android.os.Build
-import android.provider.Settings
 import android.util.{Base64, DisplayMetrics, Log}
 import android.view.View.MeasureSpec
 import android.view.{Gravity, View, Window}
@@ -128,25 +127,7 @@ object Utils {
   // Blocked > 3 seconds
   def toggleAirplaneMode(context: Context) = {
     val result = Shell.SU.run(FLUSH_DNS)
-    if (result != null && !result.isEmpty) true else if (Build.VERSION.SDK_INT < 17) {
-      toggleBelowApiLevel17(context)
-      true
-    } else false
-  }
-
-  //noinspection ScalaDeprecation
-  private def toggleBelowApiLevel17(context: Context) {
-    // Android 4.2 below
-    Settings.System.putInt(context.getContentResolver, Settings.System.AIRPLANE_MODE_ON, 1)
-    val enableIntent = new Intent(Intent.ACTION_AIRPLANE_MODE_CHANGED)
-    enableIntent.putExtra("state", true)
-    context.sendBroadcast(enableIntent)
-    Thread.sleep(3000)
-
-    Settings.System.putInt(context.getContentResolver, Settings.System.AIRPLANE_MODE_ON, 0)
-    val disableIntent = new Intent(Intent.ACTION_AIRPLANE_MODE_CHANGED)
-    disableIntent.putExtra("state", false)
-    context.sendBroadcast(disableIntent)
+    result != null && !result.isEmpty
   }
 
   def resolve(host: String, addrType: Int): Option[String] = {