global: Clean up Java

Address Java and Android lints.

Signed-off-by: Samuel Holland <samuel@sholland.org>

13 files changed, 237 insertions, 215 deletions

diff --git a/app/src/main/java/com/wireguard/android/activity/BaseActivity.java b/app/src/main/java/com/wireguard/android/activity/BaseActivity.java
index eb2de5ed..6ee9ff14 100644
--- a/app/src/main/java/com/wireguard/android/activity/BaseActivity.java
+++ b/app/src/main/java/com/wireguard/android/activity/BaseActivity.java
@@ -49,7 +49,7 @@ public abstract class BaseActivity extends AppCompatActivity {
         super.onCreate(savedInstanceState);
 
         if (Application.getComponent().getBackendType() == GoBackend.class) {
-            Intent intent = GoBackend.VpnService.prepare(this);
+            final Intent intent = GoBackend.VpnService.prepare(this);
             if (intent != null) {
                 startActivityForResult(intent, 0);
             }
diff --git a/app/src/main/java/com/wireguard/android/activity/MainActivity.java b/app/src/main/java/com/wireguard/android/activity/MainActivity.java
index bfb3be7e..307d0bf6 100644
--- a/app/src/main/java/com/wireguard/android/activity/MainActivity.java
+++ b/app/src/main/java/com/wireguard/android/activity/MainActivity.java
@@ -68,7 +68,7 @@ public class MainActivity extends BaseActivity {
             fragment =
                     ((TunnelListFragment)
                             getSupportFragmentManager().getFragments().get(0));
-        } catch (ClassCastException ignored) {
+        } catch (final ClassCastException ignored) {
         }
         if (fragment == null || !(fragment.collapseActionMenu())) {
             if (!moveToState(State.ofLayer(state.layer - 1)))
diff --git a/app/src/main/java/com/wireguard/android/activity/SettingsActivity.java b/app/src/main/java/com/wireguard/android/activity/SettingsActivity.java
index fb5e7a09..46a90daa 100644
--- a/app/src/main/java/com/wireguard/android/activity/SettingsActivity.java
+++ b/app/src/main/java/com/wireguard/android/activity/SettingsActivity.java
@@ -17,28 +17,29 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 /**
  * Interface for changing application-global persistent settings.
  */
 
 public class SettingsActivity extends AppCompatActivity {
-    private HashMap<Integer, PermissionRequestCallback> permissionRequestCallbacks = new HashMap<>();
-    private int permissionRequestCounter = 0;
+    private final Map<Integer, PermissionRequestCallback> permissionRequestCallbacks = new HashMap<>();
+    private int permissionRequestCounter;
 
-    public synchronized void ensurePermissions(String[] permissions, PermissionRequestCallback cb) {
-        List<String> needPermissions = new ArrayList<>(permissions.length);
+    public void ensurePermissions(final String[] permissions, final PermissionRequestCallback cb) {
+        final List<String> needPermissions = new ArrayList<>(permissions.length);
         for (final String permission : permissions) {
             if (ActivityCompat.checkSelfPermission(this, permission) != PackageManager.PERMISSION_GRANTED)
                 needPermissions.add(permission);
         }
         if (needPermissions.isEmpty()) {
-            int[] granted = new int[permissions.length];
+            final int[] granted = new int[permissions.length];
             Arrays.fill(granted, PackageManager.PERMISSION_GRANTED);
             cb.done(permissions, granted);
             return;
         }
-        int idx = permissionRequestCounter++;
+        final int idx = permissionRequestCounter++;
         permissionRequestCallbacks.put(idx, cb);
         ActivityCompat.requestPermissions(this, needPermissions.toArray(new String[needPermissions.size()]), idx);
     }
@@ -54,7 +55,7 @@ public class SettingsActivity extends AppCompatActivity {
     }
 
     @Override
-    public boolean onOptionsItemSelected(MenuItem item) {
+    public boolean onOptionsItemSelected(final MenuItem item) {
         switch (item.getItemId()) {
             case android.R.id.home:
                 finish();
@@ -65,7 +66,7 @@ public class SettingsActivity extends AppCompatActivity {
     }
 
     @Override
-    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
+    public void onRequestPermissionsResult(final int requestCode, @NonNull final String[] permissions, @NonNull final int[] grantResults) {
         final PermissionRequestCallback f = permissionRequestCallbacks.get(requestCode);
         if (f != null) {
             permissionRequestCallbacks.remove(requestCode);
@@ -73,7 +74,6 @@ public class SettingsActivity extends AppCompatActivity {
         }
     }
 
-    @FunctionalInterface
     public interface PermissionRequestCallback {
         void done(String[] permissions, int[] grantResults);
     }
diff --git a/app/src/main/java/com/wireguard/android/backend/GoBackend.java b/app/src/main/java/com/wireguard/android/backend/GoBackend.java
index 519f7427..e055c353 100644
--- a/app/src/main/java/com/wireguard/android/backend/GoBackend.java
+++ b/app/src/main/java/com/wireguard/android/backend/GoBackend.java
@@ -33,11 +33,11 @@ public final class GoBackend implements Backend {
         System.loadLibrary("wg-go");
     }
 
-    private Context context;
+    private final Context context;
     private Tunnel currentTunnel;
     private int currentTunnelHandle = -1;
 
-    public GoBackend(Context context) {
+    public GoBackend(final Context context) {
         this.context = context;
     }
 
@@ -108,14 +108,14 @@ public final class GoBackend implements Backend {
             if (VpnService.prepare(context) != null)
                 throw new Exception("VPN service not authorized by user");
 
-            VpnService service;
+            final VpnService service;
             if (!vpnService.isDone())
                 startVpnService();
 
             try {
                 service = vpnService.get(2, TimeUnit.SECONDS);
-            } catch (TimeoutException e) {
-                throw new Exception("Unable to start Android VPN service");
+            } catch (final TimeoutException e) {
+                throw new Exception("Unable to start Android VPN service", e);
             }
 
             if (currentTunnelHandle != -1) {
@@ -124,29 +124,32 @@ public final class GoBackend implements Backend {
             }
 
             // Build config
-            Formatter fmt = new Formatter(new StringBuilder());
             final Interface iface = config.getInterface();
-            fmt.format("replace_peers=true\n");
-            if (iface.getPrivateKey() != null)
-                fmt.format("private_key=%s\n", KeyEncoding.keyToHex(KeyEncoding.keyFromBase64(iface.getPrivateKey())));
-            if (iface.getListenPort() != 0)
-                fmt.format("listen_port=%d\n", config.getInterface().getListenPort());
-            for (final Peer peer : config.getPeers()) {
-                if (peer.getPublicKey() != null)
-                    fmt.format("public_key=%s\n", KeyEncoding.keyToHex(KeyEncoding.keyFromBase64(peer.getPublicKey())));
-                if (peer.getPreSharedKey() != null)
-                    fmt.format("preshared_key=%s\n", KeyEncoding.keyToHex(KeyEncoding.keyFromBase64(peer.getPreSharedKey())));
-                if (peer.getEndpoint() != null)
-                    fmt.format("endpoint=%s\n", peer.getResolvedEndpointString());
-                if (peer.getPersistentKeepalive() != 0)
-                    fmt.format("persistent_keepalive_interval=%d\n", peer.getPersistentKeepalive());
-                for (final IPCidr addr : peer.getAllowedIPs()) {
-                    fmt.format("allowed_ip=%s\n", addr.toString());
+            final String goConfig;
+            try (Formatter fmt = new Formatter(new StringBuilder())) {
+                fmt.format("replace_peers=true\n");
+                if (iface.getPrivateKey() != null)
+                    fmt.format("private_key=%s\n", KeyEncoding.keyToHex(KeyEncoding.keyFromBase64(iface.getPrivateKey())));
+                if (iface.getListenPort() != 0)
+                    fmt.format("listen_port=%d\n", config.getInterface().getListenPort());
+                for (final Peer peer : config.getPeers()) {
+                    if (peer.getPublicKey() != null)
+                        fmt.format("public_key=%s\n", KeyEncoding.keyToHex(KeyEncoding.keyFromBase64(peer.getPublicKey())));
+                    if (peer.getPreSharedKey() != null)
+                        fmt.format("preshared_key=%s\n", KeyEncoding.keyToHex(KeyEncoding.keyFromBase64(peer.getPreSharedKey())));
+                    if (peer.getEndpoint() != null)
+                        fmt.format("endpoint=%s\n", peer.getResolvedEndpointString());
+                    if (peer.getPersistentKeepalive() != 0)
+                        fmt.format("persistent_keepalive_interval=%d\n", peer.getPersistentKeepalive());
+                    for (final IPCidr addr : peer.getAllowedIPs()) {
+                        fmt.format("allowed_ip=%s\n", addr.toString());
+                    }
                 }
+                goConfig = fmt.toString();
             }
 
             // Create the vpn tunnel with android API
-            VpnService.Builder builder = service.getBuilder();
+            final VpnService.Builder builder = service.getBuilder();
             builder.setSession(tunnel.getName());
 
             for (final IPCidr addr : config.getInterface().getAddresses())
@@ -166,13 +169,13 @@ public final class GoBackend implements Backend {
             builder.setMtu(mtu);
 
             builder.setBlocking(true);
-            ParcelFileDescriptor tun = builder.establish();
+            final ParcelFileDescriptor tun = builder.establish();
             if (tun == null)
                 throw new Exception("Unable to create tun device");
 
-            currentTunnelHandle = wgTurnOn(tunnel.getName(), tun.detachFd(), fmt.toString());
+            currentTunnelHandle = wgTurnOn(tunnel.getName(), tun.detachFd(), goConfig);
             if (currentTunnelHandle < 0)
-                throw new Exception("Unable to turn tunnel on (wgTurnOn return " + currentTunnelHandle + ")");
+                throw new Exception("Unable to turn tunnel on (wgTurnOn return " + currentTunnelHandle + ')');
 
             currentTunnel = tunnel;
 
diff --git a/app/src/main/java/com/wireguard/android/backend/WgQuickBackend.java b/app/src/main/java/com/wireguard/android/backend/WgQuickBackend.java
index b91d8476..b9eb3461 100644
--- a/app/src/main/java/com/wireguard/android/backend/WgQuickBackend.java
+++ b/app/src/main/java/com/wireguard/android/backend/WgQuickBackend.java
@@ -105,14 +105,15 @@ public final class WgQuickBackend implements Backend {
         }
         final String command = String.format("wg-quick %s '%s'", state.toString().toLowerCase(), tempFile.getAbsolutePath());
         final int result = rootShell.run(null, command);
+        // noinspection ResultOfMethodCallIgnored
         tempFile.delete();
         if (result != 0)
             throw new Exception("Unable to configure tunnel (wg-quick returned " + result + ')');
     }
 
-    public final static class WgQuickChangeReceiver extends BroadcastReceiver {
+    public static final class WgQuickChangeReceiver extends BroadcastReceiver {
         @Override
-        public void onReceive(Context context, Intent intent) {
+        public void onReceive(final Context context, final Intent intent) {
             Log.d(TAG, "Refreshing tunnel states");
             Application.getComponent().getTunnelManager().refreshTunnelStates();
         }
diff --git a/app/src/main/java/com/wireguard/android/fragment/TunnelEditorFragment.java b/app/src/main/java/com/wireguard/android/fragment/TunnelEditorFragment.java
index a3760ed9..f0731587 100644
--- a/app/src/main/java/com/wireguard/android/fragment/TunnelEditorFragment.java
+++ b/app/src/main/java/com/wireguard/android/fragment/TunnelEditorFragment.java
@@ -109,10 +109,10 @@ public class TunnelEditorFragment extends BaseFragment {
     public boolean onOptionsItemSelected(final MenuItem item) {
         switch (item.getItemId()) {
             case R.id.menu_action_save:
-                Config newConfig = new Config();
+                final Config newConfig = new Config();
                 try {
                     binding.getConfig().commitData(newConfig);
-                } catch (Exception e) {
+                } catch (final Exception e) {
                     final String error = ExceptionLoggers.unwrap(e).getMessage();
                     final String tunnelName = tunnel == null ? binding.getConfig().getName() : tunnel.getName();
                     final String message = getString(R.string.config_save_error, tunnelName, error);
@@ -202,8 +202,8 @@ public class TunnelEditorFragment extends BaseFragment {
             onSelectedTunnelChanged(null, getSelectedTunnel());
         } else {
             tunnel = getSelectedTunnel();
-            Config.Observable config = savedInstanceState.getParcelable(KEY_LOCAL_CONFIG);
-            String originalName = savedInstanceState.getString(KEY_ORIGINAL_NAME);
+            final Config.Observable config = savedInstanceState.getParcelable(KEY_LOCAL_CONFIG);
+            final String originalName = savedInstanceState.getString(KEY_ORIGINAL_NAME);
             if (tunnel != null && !tunnel.getName().equals(originalName))
                 onSelectedTunnelChanged(null, tunnel);
             else
diff --git a/app/src/main/java/com/wireguard/android/fragment/TunnelListFragment.java b/app/src/main/java/com/wireguard/android/fragment/TunnelListFragment.java
index 2b81a98a..9fc7346b 100644
--- a/app/src/main/java/com/wireguard/android/fragment/TunnelListFragment.java
+++ b/app/src/main/java/com/wireguard/android/fragment/TunnelListFragment.java
@@ -43,6 +43,7 @@ import java.io.BufferedReader;
 import java.io.InputStreamReader;
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 import java.util.zip.ZipEntry;
@@ -82,7 +83,7 @@ public class TunnelListFragment extends BaseFragment {
             return;
         final ContentResolver contentResolver = activity.getContentResolver();
 
-        final List<CompletableFuture<Tunnel>> futureTunnels = new ArrayList<>();
+        final Collection<CompletableFuture<Tunnel>> futureTunnels = new ArrayList<>();
         final List<Throwable> throwables = new ArrayList<>();
         asyncWorker.supplyAsync(() -> {
             final String[] columns = {OpenableColumns.DISPLAY_NAME};
@@ -106,31 +107,32 @@ public class TunnelListFragment extends BaseFragment {
                 throw new IllegalArgumentException("File must be .conf or .zip");
 
             if (isZip) {
-                ZipInputStream zip = new ZipInputStream(contentResolver.openInputStream(uri));
-                BufferedReader reader = new BufferedReader(new InputStreamReader(zip, StandardCharsets.UTF_8));
-                ZipEntry entry;
-                while ((entry = zip.getNextEntry()) != null) {
-                    if (entry.isDirectory())
-                        continue;
-                    name = entry.getName();
-                    idx = name.lastIndexOf('/');
-                    if (idx >= 0) {
-                        if (idx >= name.length() - 1)
+                try (ZipInputStream zip = new ZipInputStream(contentResolver.openInputStream(uri))) {
+                    BufferedReader reader = new BufferedReader(new InputStreamReader(zip, StandardCharsets.UTF_8));
+                    ZipEntry entry;
+                    while ((entry = zip.getNextEntry()) != null) {
+                        if (entry.isDirectory())
                             continue;
-                        name = name.substring(name.lastIndexOf('/') + 1);
-                    }
-                    if (name.toLowerCase().endsWith(".conf"))
-                        name = name.substring(0, name.length() - ".conf".length());
-                    else
-                        continue;
-                    Config config = null;
-                    try {
-                        config = Config.from(reader);
-                    } catch (Exception e) {
-                        throwables.add(e);
+                        name = entry.getName();
+                        idx = name.lastIndexOf('/');
+                        if (idx >= 0) {
+                            if (idx >= name.length() - 1)
+                                continue;
+                            name = name.substring(name.lastIndexOf('/') + 1);
+                        }
+                        if (name.toLowerCase().endsWith(".conf"))
+                            name = name.substring(0, name.length() - ".conf".length());
+                        else
+                            continue;
+                        Config config = null;
+                        try {
+                            config = Config.from(reader);
+                        } catch (Exception e) {
+                            throwables.add(e);
+                        }
+                        if (config != null)
+                            futureTunnels.add(tunnelManager.create(name, config).toCompletableFuture());
                     }
-                    if (config != null)
-                        futureTunnels.add(tunnelManager.create(name, config).toCompletableFuture());
                 }
             } else {
                 futureTunnels.add(tunnelManager.create(name, Config.from(contentResolver.openInputStream(uri))).toCompletableFuture());
@@ -146,15 +148,15 @@ public class TunnelListFragment extends BaseFragment {
             return CompletableFuture.allOf(futureTunnels.toArray(new CompletableFuture[futureTunnels.size()]));
         }).whenComplete((future, exception) -> {
             if (exception != null) {
-                this.onTunnelImportFinished(Collections.emptyList(), Collections.singletonList(exception));
+                onTunnelImportFinished(Collections.emptyList(), Collections.singletonList(exception));
             } else {
                 future.whenComplete((ignored1, ignored2) -> {
-                    ArrayList<Tunnel> tunnels = new ArrayList<>(futureTunnels.size());
-                    for (CompletableFuture<Tunnel> futureTunnel : futureTunnels) {
+                    final List<Tunnel> tunnels = new ArrayList<>(futureTunnels.size());
+                    for (final CompletableFuture<Tunnel> futureTunnel : futureTunnels) {
                         Tunnel tunnel = null;
                         try {
                             tunnel = futureTunnel.getNow(null);
-                        } catch (Exception e) {
+                        } catch (final Exception e) {
                             throwables.add(e);
                         }
                         if (tunnel != null)
@@ -240,7 +242,7 @@ public class TunnelListFragment extends BaseFragment {
         }
     }
 
-    private void onTunnelImportFinished(final List<Tunnel> tunnels, final List<Throwable> throwables) {
+    private void onTunnelImportFinished(final List<Tunnel> tunnels, final Collection<Throwable> throwables) {
         String message = null;
 
         for (final Throwable throwable : throwables) {
diff --git a/app/src/main/java/com/wireguard/android/preference/ZipExporterPreference.java b/app/src/main/java/com/wireguard/android/preference/ZipExporterPreference.java
index b10d8388..677c56c9 100644
--- a/app/src/main/java/com/wireguard/android/preference/ZipExporterPreference.java
+++ b/app/src/main/java/com/wireguard/android/preference/ZipExporterPreference.java
@@ -22,6 +22,7 @@ import com.wireguard.config.Config;
 
 import java.io.File;
 import java.io.FileOutputStream;
+import java.io.IOException;
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.List;
@@ -39,7 +40,7 @@ public class ZipExporterPreference extends Preference {
 
     private final AsyncWorker asyncWorker;
     private final TunnelManager tunnelManager;
-    private String exportedFilePath = null;
+    private String exportedFilePath;
 
     @SuppressWarnings({"SameParameterValue", "WeakerAccess"})
     public ZipExporterPreference(final Context context, final AttributeSet attrs) {
@@ -49,9 +50,19 @@ public class ZipExporterPreference extends Preference {
         tunnelManager = applicationComponent.getTunnelManager();
     }
 
+    private static SettingsActivity getPrefActivity(final Preference preference) {
+        final Context context = preference.getContext();
+        if (context instanceof ContextThemeWrapper) {
+            if (((ContextThemeWrapper) context).getBaseContext() instanceof SettingsActivity) {
+                return ((SettingsActivity) ((ContextThemeWrapper) context).getBaseContext());
+            }
+        }
+        return null;
+    }
+
     private void exportZip() {
-        List<Tunnel> tunnels = new ArrayList<>(tunnelManager.getTunnels());
-        List<CompletableFuture<Config>> futureConfigs = new ArrayList<>(tunnels.size());
+        final List<Tunnel> tunnels = new ArrayList<>(tunnelManager.getTunnels());
+        final List<CompletableFuture<Config>> futureConfigs = new ArrayList<>(tunnels.size());
         for (final Tunnel tunnel : tunnels)
             futureConfigs.add(tunnel.getConfigAsync().toCompletableFuture());
         if (futureConfigs.isEmpty()) {
@@ -65,9 +76,9 @@ public class ZipExporterPreference extends Preference {
                             throw exception;
                         final File path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
                         final File file = new File(path, "wireguard-export.zip");
-                        try {
-                            path.mkdirs();
-                            final ZipOutputStream zip = new ZipOutputStream(new FileOutputStream(file));
+                        if (!path.mkdirs())
+                            throw new IOException("Cannot create output directory");
+                        try (ZipOutputStream zip = new ZipOutputStream(new FileOutputStream(file))) {
                             for (int i = 0; i < futureConfigs.size(); ++i) {
                                 zip.putNextEntry(new ZipEntry(tunnels.get(i).getName() + ".conf"));
                                 zip.write(futureConfigs.get(i).getNow(null).
@@ -76,6 +87,7 @@ public class ZipExporterPreference extends Preference {
                             zip.closeEntry();
                             zip.close();
                         } catch (Exception e) {
+                            // noinspection ResultOfMethodCallIgnored
                             file.delete();
                             throw e;
                         }
@@ -84,7 +96,7 @@ public class ZipExporterPreference extends Preference {
                 });
     }
 
-    private void exportZipComplete(String filePath, Throwable throwable) {
+    private void exportZipComplete(final String filePath, final Throwable throwable) {
         if (throwable != null) {
             final String error = ExceptionLoggers.unwrap(throwable).getMessage();
             final String message = getContext().getString(R.string.export_error, error);
@@ -99,16 +111,6 @@ public class ZipExporterPreference extends Preference {
         }
     }
 
-    private SettingsActivity getPrefActivity(Preference preference) {
-        Context context = preference.getContext();
-        if (context instanceof ContextThemeWrapper) {
-            if (((ContextThemeWrapper) context).getBaseContext() instanceof SettingsActivity) {
-                return ((SettingsActivity) ((ContextThemeWrapper) context).getBaseContext());
-            }
-        }
-        return null;
-    }
-
     @Override
     public CharSequence getSummary() {
         if (exportedFilePath == null)
diff --git a/app/src/main/java/com/wireguard/config/Attribute.java b/app/src/main/java/com/wireguard/config/Attribute.java
index 2d8070ac..726eaa1a 100644
--- a/app/src/main/java/com/wireguard/config/Attribute.java
+++ b/app/src/main/java/com/wireguard/config/Attribute.java
@@ -6,7 +6,6 @@ import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.net.InetAddress;
 import java.util.HashMap;
-import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.regex.Matcher;
@@ -28,9 +27,11 @@ enum Attribute {
     PRIVATE_KEY("PrivateKey"),
     PUBLIC_KEY("PublicKey");
 
+    private static final String[] EMPTY_LIST = new String[0];
     private static final Map<String, Attribute> KEY_MAP;
+    private static final Pattern LIST_SEPARATOR_PATTERN = Pattern.compile("\\s*,\\s*");
+    private static final Method NUMERIC_ADDRESS_PARSER;
     private static final Pattern SEPARATOR_PATTERN = Pattern.compile("\\s|=");
-    private static Method parseNumericAddressMethod;
 
     static {
         KEY_MAP = new HashMap<>(Attribute.values().length);
@@ -41,8 +42,8 @@ enum Attribute {
 
     static {
         try {
-            parseNumericAddressMethod = InetAddress.class.getMethod("parseNumericAddress", new Class[]{String.class});
-        } catch (Exception e) {
+            NUMERIC_ADDRESS_PARSER = InetAddress.class.getMethod("parseNumericAddress", String.class);
+        } catch (final Exception e) {
             throw new RuntimeException(e);
         }
     }
@@ -55,8 +56,8 @@ enum Attribute {
         this.token = token;
     }
 
-    public static <T> String listToString(final List<T> list) {
-        return TextUtils.join(", ", list);
+    public static <T> String iterableToString(final Iterable<T> iterable) {
+        return TextUtils.join(", ", iterable);
     }
 
     public static Attribute match(final CharSequence line) {
@@ -67,10 +68,10 @@ enum Attribute {
         if (address == null || address.isEmpty())
             throw new IllegalArgumentException("Empty address");
         try {
-            return (InetAddress) parseNumericAddressMethod.invoke(null, new Object[]{address});
-        } catch (IllegalAccessException e) {
+            return (InetAddress) NUMERIC_ADDRESS_PARSER.invoke(null, address);
+        } catch (final IllegalAccessException e) {
             throw new RuntimeException(e);
-        } catch (InvocationTargetException e) {
+        } catch (final InvocationTargetException e) {
             if (e.getCause() instanceof IllegalArgumentException)
                 throw (IllegalArgumentException) e.getCause();
             else
@@ -80,8 +81,8 @@ enum Attribute {
 
     public static String[] stringToList(final String string) {
         if (string == null)
-            return new String[0];
-        return string.trim().split("\\s*,\\s*");
+            return EMPTY_LIST;
+        return LIST_SEPARATOR_PATTERN.split(string.trim());
     }
 
     public String composeWith(final Object value) {
@@ -92,8 +93,8 @@ enum Attribute {
         return String.format(Locale.getDefault(), "%s = %d%n", token, value);
     }
 
-    public <T> String composeWith(final List<T> value) {
-        return String.format("%s = %s%n", token, listToString(value));
+    public <T> String composeWith(final Iterable<T> value) {
+        return String.format("%s = %s%n", token, iterableToString(value));
     }
 
     public String parse(final CharSequence line) {
diff --git a/app/src/main/java/com/wireguard/config/Config.java b/app/src/main/java/com/wireguard/config/Config.java
index 7e6ff77c..ca2d3b1f 100644
--- a/app/src/main/java/com/wireguard/config/Config.java
+++ b/app/src/main/java/com/wireguard/config/Config.java
@@ -90,7 +90,7 @@ public class Config {
         private Interface.Observable observableInterface;
         private ObservableList<Peer.Observable> observablePeers;
 
-        public Observable(Config parent, String name) {
+        public Observable(final Config parent, final String name) {
             this.name = name;
             loadData(parent);
         }
@@ -102,11 +102,11 @@ public class Config {
             in.readTypedList(observablePeers, Peer.Observable.CREATOR);
         }
 
-        public void commitData(Config parent) {
-            this.observableInterface.commitData(parent.interfaceSection);
-            List<Peer> newPeers = new ArrayList<>(this.observablePeers.size());
-            for (Peer.Observable observablePeer : this.observablePeers) {
-                Peer peer = new Peer();
+        public void commitData(final Config parent) {
+            observableInterface.commitData(parent.interfaceSection);
+            final List<Peer> newPeers = new ArrayList<>(observablePeers.size());
+            for (final Peer.Observable observablePeer : observablePeers) {
+                final Peer peer = new Peer();
                 observablePeer.commitData(peer);
                 newPeers.add(peer);
             }
@@ -134,16 +134,16 @@ public class Config {
             return observablePeers;
         }
 
-        public void loadData(Config parent) {
-            this.observableInterface = new Interface.Observable(parent == null ? null : parent.interfaceSection);
-            this.observablePeers = new ObservableArrayList<>();
+        protected void loadData(final Config parent) {
+            observableInterface = new Interface.Observable(parent == null ? null : parent.interfaceSection);
+            observablePeers = new ObservableArrayList<>();
             if (parent != null) {
-                for (Peer peer : parent.getPeers())
-                    this.observablePeers.add(new Peer.Observable(peer));
+                for (final Peer peer : parent.getPeers())
+                    observablePeers.add(new Peer.Observable(peer));
             }
         }
 
-        public void setName(String name) {
+        public void setName(final String name) {
             this.name = name;
             notifyPropertyChanged(BR.name);
         }
diff --git a/app/src/main/java/com/wireguard/config/IPCidr.java b/app/src/main/java/com/wireguard/config/IPCidr.java
index 41d43cd6..a0135d15 100644
--- a/app/src/main/java/com/wireguard/config/IPCidr.java
+++ b/app/src/main/java/com/wireguard/config/IPCidr.java
@@ -6,17 +6,17 @@ import java.net.InetAddress;
 import java.util.Locale;
 
 public class IPCidr {
-    private InetAddress address;
+    private final InetAddress address;
     private int cidr;
 
     public IPCidr(String in) {
         cidr = -1;
-        int slash = in.lastIndexOf('/');
+        final int slash = in.lastIndexOf('/');
         if (slash != -1 && slash < in.length() - 1) {
             try {
                 cidr = Integer.parseInt(in.substring(slash + 1), 10);
                 in = in.substring(0, slash);
-            } catch (Exception ignored) {
+            } catch (final Exception ignored) {
             }
         }
         address = Attribute.parseIPString(in);
diff --git a/app/src/main/java/com/wireguard/config/Interface.java b/app/src/main/java/com/wireguard/config/Interface.java
index ff69ccaf..37186206 100644
--- a/app/src/main/java/com/wireguard/config/Interface.java
+++ b/app/src/main/java/com/wireguard/config/Interface.java
@@ -9,7 +9,7 @@ import com.wireguard.android.BR;
 import com.wireguard.crypto.Keypair;
 
 import java.net.InetAddress;
-import java.util.LinkedList;
+import java.util.ArrayList;
 import java.util.List;
 
 /**
@@ -17,30 +17,31 @@ import java.util.List;
  */
 
 public class Interface {
-    private List<IPCidr> addressList;
-    private List<InetAddress> dnsList;
+    private final List<IPCidr> addressList;
+    private final List<InetAddress> dnsList;
     private Keypair keypair;
     private int listenPort;
     private int mtu;
+
     public Interface() {
-        addressList = new LinkedList<>();
-        dnsList = new LinkedList<>();
+        addressList = new ArrayList<>();
+        dnsList = new ArrayList<>();
     }
 
-    private void addAddresses(String[] addresses) {
+    private void addAddresses(final String[] addresses) {
         if (addresses != null && addresses.length > 0) {
             for (final String addr : addresses) {
                 if (addr.isEmpty())
                     throw new IllegalArgumentException("Address is empty");
-                this.addressList.add(new IPCidr(addr));
+                addressList.add(new IPCidr(addr));
             }
         }
     }
 
-    private void addDnses(String[] dnses) {
+    private void addDnses(final String[] dnses) {
         if (dnses != null && dnses.length > 0) {
             for (final String dns : dnses) {
-                this.dnsList.add(Attribute.parseIPString(dns));
+                dnsList.add(Attribute.parseIPString(dns));
             }
         }
     }
@@ -48,7 +49,7 @@ public class Interface {
     private String getAddressString() {
         if (addressList.isEmpty())
             return null;
-        return Attribute.listToString(addressList);
+        return Attribute.iterableToString(addressList);
     }
 
     public IPCidr[] getAddresses() {
@@ -58,11 +59,11 @@ public class Interface {
     private String getDnsString() {
         if (dnsList.isEmpty())
             return null;
-        return Attribute.listToString(getDnsStrings());
+        return Attribute.iterableToString(getDnsStrings());
     }
 
     private List<String> getDnsStrings() {
-        List<String> strings = new LinkedList<>();
+        final List<String> strings = new ArrayList<>();
         for (final InetAddress addr : dnsList)
             strings.add(addr.getHostAddress());
         return strings;
@@ -106,31 +107,38 @@ public class Interface {
 
     public void parse(final String line) {
         final Attribute key = Attribute.match(line);
-        if (key == Attribute.ADDRESS)
-            addAddresses(key.parseList(line));
-        else if (key == Attribute.DNS)
-            addDnses(key.parseList(line));
-        else if (key == Attribute.LISTEN_PORT)
-            setListenPortString(key.parse(line));
-        else if (key == Attribute.MTU)
-            setMtuString(key.parse(line));
-        else if (key == Attribute.PRIVATE_KEY)
-            setPrivateKey(key.parse(line));
-        else
-            throw new IllegalArgumentException(line);
+        switch (key) {
+            case ADDRESS:
+                addAddresses(key.parseList(line));
+                break;
+            case DNS:
+                addDnses(key.parseList(line));
+                break;
+            case LISTEN_PORT:
+                setListenPortString(key.parse(line));
+                break;
+            case MTU:
+                setMtuString(key.parse(line));
+                break;
+            case PRIVATE_KEY:
+                setPrivateKey(key.parse(line));
+                break;
+            default:
+                throw new IllegalArgumentException(line);
+        }
     }
 
     private void setAddressString(final String addressString) {
-        this.addressList.clear();
+        addressList.clear();
         addAddresses(Attribute.stringToList(addressString));
     }
 
     private void setDnsString(final String dnsString) {
-        this.dnsList.clear();
+        dnsList.clear();
         addDnses(Attribute.stringToList(dnsString));
     }
 
-    private void setListenPort(int listenPort) {
+    private void setListenPort(final int listenPort) {
         this.listenPort = listenPort;
     }
 
@@ -141,7 +149,7 @@ public class Interface {
             setListenPort(0);
     }
 
-    private void setMtu(int mtu) {
+    private void setMtu(final int mtu) {
         this.mtu = mtu;
     }
 
@@ -155,10 +163,7 @@ public class Interface {
     private void setPrivateKey(String privateKey) {
         if (privateKey != null && privateKey.isEmpty())
             privateKey = null;
-        if (privateKey == null)
-            keypair = null;
-        else
-            keypair = new Keypair(privateKey);
+        keypair = privateKey == null ? null : new Keypair(privateKey);
     }
 
     @Override
@@ -196,7 +201,7 @@ public class Interface {
         private String privateKey;
         private String publicKey;
 
-        public Observable(Interface parent) {
+        public Observable(final Interface parent) {
             if (parent != null)
                 loadData(parent);
         }
@@ -210,12 +215,12 @@ public class Interface {
             mtu = in.readString();
         }
 
-        public void commitData(Interface parent) {
-            parent.setAddressString(this.addresses);
-            parent.setDnsString(this.dnses);
-            parent.setPrivateKey(this.privateKey);
-            parent.setListenPortString(this.listenPort);
-            parent.setMtuString(this.mtu);
+        public void commitData(final Interface parent) {
+            parent.setAddressString(addresses);
+            parent.setDnsString(dnses);
+            parent.setPrivateKey(privateKey);
+            parent.setListenPortString(listenPort);
+            parent.setMtuString(mtu);
             loadData(parent);
             notifyChange();
         }
@@ -226,7 +231,7 @@ public class Interface {
         }
 
         public void generateKeypair() {
-            Keypair keypair = new Keypair();
+            final Keypair keypair = new Keypair();
             privateKey = keypair.getPrivateKey();
             publicKey = keypair.getPublicKey();
             notifyPropertyChanged(BR.privateKey);
@@ -263,42 +268,42 @@ public class Interface {
             return publicKey;
         }
 
-        public void loadData(Interface parent) {
-            this.addresses = parent.getAddressString();
-            this.dnses = parent.getDnsString();
-            this.publicKey = parent.getPublicKey();
-            this.privateKey = parent.getPrivateKey();
-            this.listenPort = parent.getListenPortString();
-            this.mtu = parent.getMtuString();
+        protected void loadData(final Interface parent) {
+            addresses = parent.getAddressString();
+            dnses = parent.getDnsString();
+            publicKey = parent.getPublicKey();
+            privateKey = parent.getPrivateKey();
+            listenPort = parent.getListenPortString();
+            mtu = parent.getMtuString();
         }
 
-        public void setAddresses(String addresses) {
+        public void setAddresses(final String addresses) {
             this.addresses = addresses;
             notifyPropertyChanged(BR.addresses);
         }
 
-        public void setDnses(String dnses) {
+        public void setDnses(final String dnses) {
             this.dnses = dnses;
             notifyPropertyChanged(BR.dnses);
         }
 
-        public void setListenPort(String listenPort) {
+        public void setListenPort(final String listenPort) {
             this.listenPort = listenPort;
             notifyPropertyChanged(BR.listenPort);
         }
 
-        public void setMtu(String mtu) {
+        public void setMtu(final String mtu) {
             this.mtu = mtu;
             notifyPropertyChanged(BR.mtu);
         }
 
-        public void setPrivateKey(String privateKey) {
+        public void setPrivateKey(final String privateKey) {
             this.privateKey = privateKey;
 
             try {
-                this.publicKey = new Keypair(privateKey).getPublicKey();
-            } catch (IllegalArgumentException ignored) {
-                this.publicKey = "";
+                publicKey = new Keypair(privateKey).getPublicKey();
+            } catch (final IllegalArgumentException ignored) {
+                publicKey = "";
             }
 
             notifyPropertyChanged(BR.privateKey);
diff --git a/app/src/main/java/com/wireguard/config/Peer.java b/app/src/main/java/com/wireguard/config/Peer.java
index 9f71089f..413a8d6e 100644
--- a/app/src/main/java/com/wireguard/config/Peer.java
+++ b/app/src/main/java/com/wireguard/config/Peer.java
@@ -13,7 +13,7 @@ import java.net.InetSocketAddress;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.net.UnknownHostException;
-import java.util.LinkedList;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Locale;
 
@@ -22,19 +22,20 @@ import java.util.Locale;
  */
 
 public class Peer {
-    private List<IPCidr> allowedIPsList;
+    private final List<IPCidr> allowedIPsList;
     private InetSocketAddress endpoint;
     private int persistentKeepalive;
     private String preSharedKey;
     private String publicKey;
+
     public Peer() {
-        allowedIPsList = new LinkedList<>();
+        allowedIPsList = new ArrayList<>();
     }
 
-    private void addAllowedIPs(String[] allowedIPs) {
+    private void addAllowedIPs(final String[] allowedIPs) {
         if (allowedIPs != null && allowedIPs.length > 0) {
             for (final String allowedIP : allowedIPs) {
-                this.allowedIPsList.add(new IPCidr(allowedIP));
+                allowedIPsList.add(new IPCidr(allowedIP));
             }
         }
     }
@@ -46,7 +47,7 @@ public class Peer {
     private String getAllowedIPsString() {
         if (allowedIPsList.isEmpty())
             return null;
-        return Attribute.listToString(allowedIPsList);
+        return Attribute.iterableToString(allowedIPsList);
     }
 
     public InetSocketAddress getEndpoint() {
@@ -97,38 +98,45 @@ public class Peer {
 
     public void parse(final String line) {
         final Attribute key = Attribute.match(line);
-        if (key == Attribute.ALLOWED_IPS)
-            addAllowedIPs(key.parseList(line));
-        else if (key == Attribute.ENDPOINT)
-            setEndpointString(key.parse(line));
-        else if (key == Attribute.PERSISTENT_KEEPALIVE)
-            setPersistentKeepaliveString(key.parse(line));
-        else if (key == Attribute.PRESHARED_KEY)
-            setPreSharedKey(key.parse(line));
-        else if (key == Attribute.PUBLIC_KEY)
-            setPublicKey(key.parse(line));
-        else
-            throw new IllegalArgumentException(line);
+        switch (key) {
+            case ALLOWED_IPS:
+                addAllowedIPs(key.parseList(line));
+                break;
+            case ENDPOINT:
+                setEndpointString(key.parse(line));
+                break;
+            case PERSISTENT_KEEPALIVE:
+                setPersistentKeepaliveString(key.parse(line));
+                break;
+            case PRESHARED_KEY:
+                setPreSharedKey(key.parse(line));
+                break;
+            case PUBLIC_KEY:
+                setPublicKey(key.parse(line));
+                break;
+            default:
+                throw new IllegalArgumentException(line);
+        }
     }
 
     private void setAllowedIPsString(final String allowedIPsString) {
-        this.allowedIPsList.clear();
+        allowedIPsList.clear();
         addAllowedIPs(Attribute.stringToList(allowedIPsString));
     }
 
-    private void setEndpoint(InetSocketAddress endpoint) {
+    private void setEndpoint(final InetSocketAddress endpoint) {
         this.endpoint = endpoint;
     }
 
     private void setEndpointString(final String endpoint) {
         if (endpoint != null && !endpoint.isEmpty()) {
-            InetSocketAddress constructedEndpoint;
+            final InetSocketAddress constructedEndpoint;
             if (endpoint.indexOf('/') != -1 || endpoint.indexOf('?') != -1 || endpoint.indexOf('#') != -1)
                 throw new IllegalArgumentException("Forbidden characters in endpoint");
-            URI uri;
+            final URI uri;
             try {
                 uri = new URI("wg://" + endpoint);
-            } catch (URISyntaxException e) {
+            } catch (final URISyntaxException e) {
                 throw new IllegalArgumentException(e);
             }
             constructedEndpoint = InetSocketAddress.createUnresolved(uri.getHost(), uri.getPort());
@@ -137,11 +145,11 @@ public class Peer {
             setEndpoint(null);
     }
 
-    private void setPersistentKeepalive(int persistentKeepalive) {
+    private void setPersistentKeepalive(final int persistentKeepalive) {
         this.persistentKeepalive = persistentKeepalive;
     }
 
-    private void setPersistentKeepaliveString(String persistentKeepalive) {
+    private void setPersistentKeepaliveString(final String persistentKeepalive) {
         if (persistentKeepalive != null && !persistentKeepalive.isEmpty())
             setPersistentKeepalive(Integer.parseInt(persistentKeepalive, 10));
         else
@@ -198,7 +206,7 @@ public class Peer {
         private String preSharedKey;
         private String publicKey;
 
-        public Observable(Peer parent) {
+        public Observable(final Peer parent) {
             loadData(parent);
         }
 
@@ -214,12 +222,12 @@ public class Peer {
             return new Observable(new Peer());
         }
 
-        public void commitData(Peer parent) {
-            parent.setAllowedIPsString(this.allowedIPs);
-            parent.setEndpointString(this.endpoint);
-            parent.setPersistentKeepaliveString(this.persistentKeepalive);
-            parent.setPreSharedKey(this.preSharedKey);
-            parent.setPublicKey(this.publicKey);
+        public void commitData(final Peer parent) {
+            parent.setAllowedIPsString(allowedIPs);
+            parent.setEndpointString(endpoint);
+            parent.setPersistentKeepaliveString(persistentKeepalive);
+            parent.setPreSharedKey(preSharedKey);
+            parent.setPublicKey(publicKey);
             if (parent.getPublicKey() == null)
                 throw new IllegalArgumentException("Peer public key may not be empty");
             loadData(parent);
@@ -256,35 +264,35 @@ public class Peer {
             return publicKey;
         }
 
-        public void loadData(Peer parent) {
-            this.allowedIPs = parent.getAllowedIPsString();
-            this.endpoint = parent.getEndpointString();
-            this.persistentKeepalive = parent.getPersistentKeepaliveString();
-            this.preSharedKey = parent.getPreSharedKey();
-            this.publicKey = parent.getPublicKey();
+        protected void loadData(final Peer parent) {
+            allowedIPs = parent.getAllowedIPsString();
+            endpoint = parent.getEndpointString();
+            persistentKeepalive = parent.getPersistentKeepaliveString();
+            preSharedKey = parent.getPreSharedKey();
+            publicKey = parent.getPublicKey();
         }
 
-        public void setAllowedIPs(String allowedIPs) {
+        public void setAllowedIPs(final String allowedIPs) {
             this.allowedIPs = allowedIPs;
             notifyPropertyChanged(BR.allowedIPs);
         }
 
-        public void setEndpoint(String endpoint) {
+        public void setEndpoint(final String endpoint) {
             this.endpoint = endpoint;
             notifyPropertyChanged(BR.endpoint);
         }
 
-        public void setPersistentKeepalive(String persistentKeepalive) {
+        public void setPersistentKeepalive(final String persistentKeepalive) {
             this.persistentKeepalive = persistentKeepalive;
             notifyPropertyChanged(BR.persistentKeepalive);
         }
 
-        public void setPreSharedKey(String preSharedKey) {
+        public void setPreSharedKey(final String preSharedKey) {
             this.preSharedKey = preSharedKey;
             notifyPropertyChanged(BR.preSharedKey);
         }
 
-        public void setPublicKey(String publicKey) {
+        public void setPublicKey(final String publicKey) {
             this.publicKey = publicKey;
             notifyPropertyChanged(BR.publicKey);
         }