diff --git a/app/src/main/java/ch/dissem/apps/abit/AbstractItemListFragment.java b/app/src/main/java/ch/dissem/apps/abit/AbstractItemListFragment.java
index 5432210..df96b43 100644
--- a/app/src/main/java/ch/dissem/apps/abit/AbstractItemListFragment.java
+++ b/app/src/main/java/ch/dissem/apps/abit/AbstractItemListFragment.java
@@ -37,7 +37,7 @@ public abstract class AbstractItemListFragment<T> extends ListFragment implement
      * A dummy implementation of the {@link ListSelectionListener} interface that does
      * nothing. Used only when this fragment is not attached to an activity.
      */
-    private static ListSelectionListener<Object> dummyCallbacks = plaintext -> {
+    private static final ListSelectionListener<Object> dummyCallbacks = plaintext -> {
     };
     /**
      * The fragment's current callback object, which is notified of list item
diff --git a/app/src/main/java/ch/dissem/apps/abit/AddressListFragment.java b/app/src/main/java/ch/dissem/apps/abit/AddressListFragment.java
index 5168422..57aa3dd 100644
--- a/app/src/main/java/ch/dissem/apps/abit/AddressListFragment.java
+++ b/app/src/main/java/ch/dissem/apps/abit/AddressListFragment.java
@@ -144,11 +144,6 @@ public class AddressListFragment extends AbstractItemListFragment<BitmessageAddr
         return view;
     }
 
-    @Override
-    public void startActivityForResult(Intent intent, int requestCode) {
-        super.startActivityForResult(intent, requestCode);
-    }
-
     @Override
     public void onActivityResult(int requestCode, int resultCode, Intent data) {
         if (data != null && data.hasExtra("SCAN_RESULT")) {
diff --git a/app/src/main/java/ch/dissem/apps/abit/CreateAddressActivity.java b/app/src/main/java/ch/dissem/apps/abit/CreateAddressActivity.java
index 1f6065a..eff13da 100644
--- a/app/src/main/java/ch/dissem/apps/abit/CreateAddressActivity.java
+++ b/app/src/main/java/ch/dissem/apps/abit/CreateAddressActivity.java
@@ -20,7 +20,6 @@ import android.app.Activity;
 import android.net.Uri;
 import android.os.Bundle;
 import android.support.v7.app.AppCompatActivity;
-import android.view.View;
 import android.widget.Button;
 import android.widget.EditText;
 import android.widget.Switch;
@@ -61,34 +60,28 @@ public class CreateAddressActivity extends AppCompatActivity {
         }
 
         final Button cancel = (Button) findViewById(R.id.cancel);
-        cancel.setOnClickListener(new View.OnClickListener() {
-            @Override
-            public void onClick(View v) {
-                setResult(Activity.RESULT_CANCELED);
-                finish();
-            }
+        cancel.setOnClickListener(v -> {
+            setResult(Activity.RESULT_CANCELED);
+            finish();
         });
         final Button ok = (Button) findViewById(R.id.do_import);
-        ok.setOnClickListener(new View.OnClickListener() {
-            @Override
-            public void onClick(View v) {
-                String addressText = String.valueOf(address.getText()).trim();
-                try {
-                    BitmessageAddress bmAddress = new BitmessageAddress(addressText);
-                    bmAddress.setAlias(label.getText().toString());
+        ok.setOnClickListener(v -> {
+            String addressText = String.valueOf(address.getText()).trim();
+            try {
+                BitmessageAddress bmAddress = new BitmessageAddress(addressText);
+                bmAddress.setAlias(label.getText().toString());
 
-                    BitmessageContext bmc = Singleton.getBitmessageContext
-                            (CreateAddressActivity.this);
-                    bmc.addContact(bmAddress);
-                    if (subscribe.isChecked()) {
-                        bmc.addSubscribtion(bmAddress);
-                    }
-
-                    setResult(Activity.RESULT_OK);
-                    finish();
-                } catch (RuntimeException e) {
-                    address.setError(getString(R.string.error_illegal_address));
+                BitmessageContext bmc = Singleton.getBitmessageContext
+                    (CreateAddressActivity.this);
+                bmc.addContact(bmAddress);
+                if (subscribe.isChecked()) {
+                    bmc.addSubscribtion(bmAddress);
                 }
+
+                setResult(Activity.RESULT_OK);
+                finish();
+            } catch (RuntimeException e) {
+                address.setError(getString(R.string.error_illegal_address));
             }
         });
     }
diff --git a/app/src/main/java/ch/dissem/apps/abit/DetailActivity.java b/app/src/main/java/ch/dissem/apps/abit/DetailActivity.java
index fb94ef2..f725c46 100644
--- a/app/src/main/java/ch/dissem/apps/abit/DetailActivity.java
+++ b/app/src/main/java/ch/dissem/apps/abit/DetailActivity.java
@@ -12,7 +12,7 @@ import com.mikepenz.materialize.MaterializeBuilder;
 /**
  * @author Christian Basler
  */
-public class DetailActivity extends AppCompatActivity {
+public abstract class DetailActivity extends AppCompatActivity {
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
diff --git a/app/src/main/java/ch/dissem/apps/abit/Identicon.java b/app/src/main/java/ch/dissem/apps/abit/Identicon.java
index a8da2c3..fc6122c 100644
--- a/app/src/main/java/ch/dissem/apps/abit/Identicon.java
+++ b/app/src/main/java/ch/dissem/apps/abit/Identicon.java
@@ -31,10 +31,10 @@ public class Identicon extends Drawable {
     private static final int CENTER_COLUMN = 5;
 
     private final Paint paint;
-    private int color;
-    private int background;
-    private boolean[][] fields;
-    private boolean chan;
+    private final int color;
+    private final int background;
+    private final boolean[][] fields;
+    private final boolean chan;
     private final TextPaint textPaint;
 
     public Identicon(BitmessageAddress input) {
diff --git a/app/src/main/java/ch/dissem/apps/abit/InputWifFragment.java b/app/src/main/java/ch/dissem/apps/abit/InputWifFragment.java
index 8ccdf5d..d1498ed 100644
--- a/app/src/main/java/ch/dissem/apps/abit/InputWifFragment.java
+++ b/app/src/main/java/ch/dissem/apps/abit/InputWifFragment.java
@@ -28,7 +28,6 @@ import android.view.ViewGroup;
 import android.widget.TextView;
 import android.widget.Toast;
 
-import com.github.angads25.filepicker.controller.DialogSelectionListener;
 import com.github.angads25.filepicker.model.DialogConfigs;
 import com.github.angads25.filepicker.model.DialogProperties;
 import com.github.angads25.filepicker.view.FilePickerDialog;
@@ -61,19 +60,16 @@ public class InputWifFragment extends Fragment {
         View view = inflater.inflate(R.layout.fragment_import_input, container, false);
         wifData = (TextView) view.findViewById(R.id.wif_input);
 
-        view.findViewById(R.id.next).setOnClickListener(new View.OnClickListener() {
-            @Override
-            public void onClick(View v) {
-                Bundle bundle = new Bundle();
-                bundle.putString(WIF_DATA, wifData.getText().toString());
+        view.findViewById(R.id.next).setOnClickListener(v -> {
+            Bundle bundle = new Bundle();
+            bundle.putString(WIF_DATA, wifData.getText().toString());
 
-                ImportIdentitiesFragment fragment = new ImportIdentitiesFragment();
-                fragment.setArguments(bundle);
+            ImportIdentitiesFragment fragment = new ImportIdentitiesFragment();
+            fragment.setArguments(bundle);
 
-                getFragmentManager().beginTransaction()
-                    .replace(R.id.content, fragment)
-                    .commit();
-            }
+            getFragmentManager().beginTransaction()
+                .replace(R.id.content, fragment)
+                .commit();
         });
         return view;
     }
@@ -93,26 +89,23 @@ public class InputWifFragment extends Fragment {
         properties.extensions = null;
         FilePickerDialog dialog = new FilePickerDialog(getActivity(), properties);
         dialog.setTitle(getString(R.string.select_file_title));
-        dialog.setDialogSelectionListener(new DialogSelectionListener() {
-            @Override
-            public void onSelectedFilePaths(String[] files) {
-                if (files.length > 0) {
-                    try (InputStream in = new FileInputStream(files[0])) {
-                        ByteArrayOutputStream data = new ByteArrayOutputStream();
-                        byte[] buffer = new byte[1024];
-                        int length;
-                        //noinspection ConstantConditions
-                        while ((length = in.read(buffer)) != -1) {
-                            data.write(buffer, 0, length);
-                        }
-                        wifData.setText(data.toString("UTF-8"));
-                    } catch (IOException e) {
-                        Toast.makeText(
-                            getActivity(),
-                            R.string.error_loading_data,
-                            Toast.LENGTH_SHORT
-                        ).show();
+        dialog.setDialogSelectionListener(files -> {
+            if (files.length > 0) {
+                try (InputStream in = new FileInputStream(files[0])) {
+                    ByteArrayOutputStream data = new ByteArrayOutputStream();
+                    byte[] buffer = new byte[1024];
+                    int length;
+                    //noinspection ConstantConditions
+                    while ((length = in.read(buffer)) != -1) {
+                        data.write(buffer, 0, length);
                     }
+                    wifData.setText(data.toString("UTF-8"));
+                } catch (IOException e) {
+                    Toast.makeText(
+                        getActivity(),
+                        R.string.error_loading_data,
+                        Toast.LENGTH_SHORT
+                    ).show();
                 }
             }
         });
diff --git a/app/src/main/java/ch/dissem/apps/abit/MessageListFragment.java b/app/src/main/java/ch/dissem/apps/abit/MessageListFragment.java
index 9328ce2..0d22d98 100644
--- a/app/src/main/java/ch/dissem/apps/abit/MessageListFragment.java
+++ b/app/src/main/java/ch/dissem/apps/abit/MessageListFragment.java
@@ -130,15 +130,12 @@ public class MessageListFragment extends Fragment implements ListHolder {
         // Show the dummy content as text in a TextView.
         FloatingActionButton fab = (FloatingActionButton) rootView.findViewById(R.id
             .fab_compose_message);
-        fab.setOnClickListener(new View.OnClickListener() {
-            @Override
-            public void onClick(View view) {
-                Intent intent = new Intent(getActivity().getApplicationContext(),
-                    ComposeMessageActivity.class);
-                intent.putExtra(ComposeMessageActivity.EXTRA_IDENTITY, Singleton.getIdentity
-                    (getActivity()));
-                startActivity(intent);
-            }
+        fab.setOnClickListener(view -> {
+            Intent intent = new Intent(getActivity().getApplicationContext(),
+                ComposeMessageActivity.class);
+            intent.putExtra(ComposeMessageActivity.EXTRA_IDENTITY, Singleton.getIdentity
+                (getActivity()));
+            startActivity(intent);
         });
 
         // touch guard manager  (this class is required to suppress scrolling while swipe-dismiss
@@ -173,7 +170,7 @@ public class MessageListFragment extends Fragment implements ListHolder {
             }
 
             @Override
-            public void onItemViewClicked(View v, boolean pinned) {
+            public void onItemViewClicked(View v) {
                 int position = recyclerView.getChildAdapterPosition(v);
                 adapter.setSelectedPosition(position);
                 if (position != RecyclerView.NO_POSITION) {
diff --git a/app/src/main/java/ch/dissem/apps/abit/SettingsFragment.java b/app/src/main/java/ch/dissem/apps/abit/SettingsFragment.java
index 60ecbeb..c905f65 100644
--- a/app/src/main/java/ch/dissem/apps/abit/SettingsFragment.java
+++ b/app/src/main/java/ch/dissem/apps/abit/SettingsFragment.java
@@ -36,8 +36,8 @@ import static ch.dissem.apps.abit.util.Constants.PREFERENCE_TRUSTED_NODE;
  * @author Christian Basler
  */
 public class SettingsFragment
-        extends PreferenceFragment
-        implements SharedPreferences.OnSharedPreferenceChangeListener {
+    extends PreferenceFragment
+    implements SharedPreferences.OnSharedPreferenceChangeListener {
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
@@ -46,27 +46,21 @@ public class SettingsFragment
         addPreferencesFromResource(R.xml.preferences);
 
         Preference about = findPreference("about");
-        about.setOnPreferenceClickListener(new Preference.OnPreferenceClickListener() {
-            @Override
-            public boolean onPreferenceClick(Preference preference) {
-                new LibsBuilder()
-                        .withActivityTitle(getActivity().getString(R.string.about))
-                        .withActivityStyle(Libs.ActivityStyle.LIGHT_DARK_TOOLBAR)
-                        .withAboutIconShown(true)
-                        .withAboutVersionShown(true)
-                        .withAboutDescription(getString(R.string.about_app))
-                        .start(getActivity());
-                return true;
-            }
+        about.setOnPreferenceClickListener(preference -> {
+            new LibsBuilder()
+                .withActivityTitle(getActivity().getString(R.string.about))
+                .withActivityStyle(Libs.ActivityStyle.LIGHT_DARK_TOOLBAR)
+                .withAboutIconShown(true)
+                .withAboutVersionShown(true)
+                .withAboutDescription(getString(R.string.about_app))
+                .start(getActivity());
+            return true;
         });
 
         Preference status = findPreference("status");
-        status.setOnPreferenceClickListener(new Preference.OnPreferenceClickListener() {
-            @Override
-            public boolean onPreferenceClick(Preference preference) {
-                startActivity(new Intent(getActivity(), StatusActivity.class));
-                return true;
-            }
+        status.setOnPreferenceClickListener(preference -> {
+            startActivity(new Intent(getActivity(), StatusActivity.class));
+            return true;
         });
     }
 
@@ -74,7 +68,7 @@ public class SettingsFragment
     public void onAttach(Context ctx) {
         super.onAttach(ctx);
         PreferenceManager.getDefaultSharedPreferences(ctx)
-                .registerOnSharedPreferenceChangeListener(this);
+            .registerOnSharedPreferenceChangeListener(this);
     }
 
     @Override
@@ -97,4 +91,4 @@ public class SettingsFragment
                 break;
         }
     }
-}
\ No newline at end of file
+}
diff --git a/app/src/main/java/ch/dissem/apps/abit/adapter/AddressSelectorAdapter.java b/app/src/main/java/ch/dissem/apps/abit/adapter/AddressSelectorAdapter.java
index 4103097..f35a52a 100644
--- a/app/src/main/java/ch/dissem/apps/abit/adapter/AddressSelectorAdapter.java
+++ b/app/src/main/java/ch/dissem/apps/abit/adapter/AddressSelectorAdapter.java
@@ -21,7 +21,6 @@ import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.CheckBox;
-import android.widget.CompoundButton;
 import android.widget.TextView;
 
 import java.util.ArrayList;
@@ -69,19 +68,16 @@ public class AddressSelectorAdapter
 
     static class ViewHolder extends RecyclerView.ViewHolder {
         public Selectable<BitmessageAddress> data;
-        public CheckBox checkbox;
-        public TextView address;
+        public final CheckBox checkbox;
+        public final TextView address;
 
         private ViewHolder(View v) {
             super(v);
             checkbox = (CheckBox) v.findViewById(R.id.checkbox);
             address = (TextView) v.findViewById(R.id.address);
-            checkbox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
-                @Override
-                public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
-                    if (data != null) {
-                        data.selected = isChecked;
-                    }
+            checkbox.setOnCheckedChangeListener((buttonView, isChecked) -> {
+                if (data != null) {
+                    data.selected = isChecked;
                 }
             });
         }
diff --git a/app/src/main/java/ch/dissem/apps/abit/adapter/SwipeableMessageAdapter.java b/app/src/main/java/ch/dissem/apps/abit/adapter/SwipeableMessageAdapter.java
index 2e4775b..53db232 100644
--- a/app/src/main/java/ch/dissem/apps/abit/adapter/SwipeableMessageAdapter.java
+++ b/app/src/main/java/ch/dissem/apps/abit/adapter/SwipeableMessageAdapter.java
@@ -59,8 +59,8 @@ public class SwipeableMessageAdapter
 
     private List<Plaintext> data = Collections.emptyList();
     private EventListener eventListener;
-    private View.OnClickListener itemViewOnClickListener;
-    private View.OnClickListener swipeableViewContainerOnClickListener;
+    private final View.OnClickListener itemViewOnClickListener;
+    private final View.OnClickListener swipeableViewContainerOnClickListener;
 
     private Label label;
     private int selectedPosition;
@@ -75,12 +75,12 @@ public class SwipeableMessageAdapter
 
         void onItemArchived(Plaintext item);
 
-        void onItemViewClicked(View v, boolean pinned);
+        void onItemViewClicked(View v);
     }
 
     @SuppressWarnings("WeakerAccess")
     static class ViewHolder extends AbstractSwipeableItemViewHolder {
-        public FrameLayout container;
+        public final FrameLayout container;
         public final ImageView avatar;
         public final TextView sender;
         public final TextView subject;
@@ -102,18 +102,8 @@ public class SwipeableMessageAdapter
     }
 
     public SwipeableMessageAdapter() {
-        itemViewOnClickListener = new View.OnClickListener() {
-            @Override
-            public void onClick(View v) {
-                onItemViewClick(v);
-            }
-        };
-        swipeableViewContainerOnClickListener = new View.OnClickListener() {
-            @Override
-            public void onClick(View v) {
-                onSwipeableViewContainerClick(v);
-            }
-        };
+        itemViewOnClickListener = this::onItemViewClick;
+        swipeableViewContainerOnClickListener = this::onSwipeableViewContainerClick;
 
         // SwipeableItemAdapter requires stable ID, and also
         // have to implement the getItemId() method appropriately.
@@ -127,14 +117,14 @@ public class SwipeableMessageAdapter
 
     private void onItemViewClick(View v) {
         if (eventListener != null) {
-            eventListener.onItemViewClicked(v, true); // pinned
+            eventListener.onItemViewClicked(v);
         }
     }
 
     private void onSwipeableViewContainerClick(View v) {
         if (eventListener != null) {
             eventListener.onItemViewClicked(
-                RecyclerViewAdapterUtils.getParentViewHolderItemView(v), false);  // not pinned
+                RecyclerViewAdapterUtils.getParentViewHolderItemView(v));
         }
     }
 
diff --git a/app/src/main/java/ch/dissem/apps/abit/dialog/AddIdentityDialogFragment.java b/app/src/main/java/ch/dissem/apps/abit/dialog/AddIdentityDialogFragment.java
index 710ead0..59e16b6 100644
--- a/app/src/main/java/ch/dissem/apps/abit/dialog/AddIdentityDialogFragment.java
+++ b/app/src/main/java/ch/dissem/apps/abit/dialog/AddIdentityDialogFragment.java
@@ -19,7 +19,6 @@ package ch.dissem.apps.abit.dialog;
 import android.annotation.SuppressLint;
 import android.app.AlertDialog;
 import android.content.Context;
-import android.content.DialogInterface;
 import android.content.Intent;
 import android.os.AsyncTask;
 import android.os.Bundle;
@@ -61,56 +60,47 @@ public class AddIdentityDialogFragment extends AppCompatDialogFragment {
         getDialog().setTitle(R.string.add_identity);
         View view = inflater.inflate(R.layout.dialog_add_identity, container, false);
         final RadioGroup radioGroup = (RadioGroup) view.findViewById(R.id.radioGroup);
-        view.findViewById(R.id.ok).setOnClickListener(new View.OnClickListener() {
-            @Override
-            public void onClick(View v) {
-                final Context ctx = getActivity().getBaseContext();
-                switch (radioGroup.getCheckedRadioButtonId()) {
-                    case R.id.create_identity:
-                        Toast.makeText(ctx,
-                            R.string.toast_long_running_operation,
-                            Toast.LENGTH_SHORT).show();
-                        new AsyncTask<Void, Void, BitmessageAddress>() {
-                            @Override
-                            protected BitmessageAddress doInBackground(Void... args) {
-                                return bmc.createIdentity(false, Pubkey.Feature.DOES_ACK);
-                            }
+        view.findViewById(R.id.ok).setOnClickListener(v -> {
+            final Context ctx = getActivity().getBaseContext();
+            switch (radioGroup.getCheckedRadioButtonId()) {
+                case R.id.create_identity:
+                    Toast.makeText(ctx,
+                        R.string.toast_long_running_operation,
+                        Toast.LENGTH_SHORT).show();
+                    new AsyncTask<Void, Void, BitmessageAddress>() {
+                        @Override
+                        protected BitmessageAddress doInBackground(Void... args) {
+                            return bmc.createIdentity(false, Pubkey.Feature.DOES_ACK);
+                        }
 
-                            @Override
-                            protected void onPostExecute(BitmessageAddress chan) {
-                                Toast.makeText(ctx,
-                                    R.string.toast_identity_created,
-                                    Toast.LENGTH_SHORT).show();
-                                MainActivity mainActivity = MainActivity.getInstance();
-                                if (mainActivity != null) {
-                                    mainActivity.addIdentityEntry(chan);
-                                }
+                        @Override
+                        protected void onPostExecute(BitmessageAddress chan) {
+                            Toast.makeText(ctx,
+                                R.string.toast_identity_created,
+                                Toast.LENGTH_SHORT).show();
+                            MainActivity mainActivity = MainActivity.getInstance();
+                            if (mainActivity != null) {
+                                mainActivity.addIdentityEntry(chan);
                             }
-                        }.execute();
-                        break;
-                    case R.id.import_identity:
-                        startActivity(new Intent(ctx, ImportIdentityActivity.class));
-                        break;
-                    case R.id.add_chan:
-                        addChanDialog();
-                        break;
-                    case R.id.add_deterministic_address:
-                        new DeterministicIdentityDialogFragment().show(getFragmentManager(),
-                            "dialog");
-                        break;
-                    default:
-                        return;
-                }
-                dismiss();
+                        }
+                    }.execute();
+                    break;
+                case R.id.import_identity:
+                    startActivity(new Intent(ctx, ImportIdentityActivity.class));
+                    break;
+                case R.id.add_chan:
+                    addChanDialog();
+                    break;
+                case R.id.add_deterministic_address:
+                    new DeterministicIdentityDialogFragment().show(getFragmentManager(),
+                        "dialog");
+                    break;
+                default:
+                    return;
             }
+            dismiss();
         });
-        view.findViewById(R.id.dismiss)
-            .setOnClickListener(new View.OnClickListener() {
-                @Override
-                public void onClick(View v) {
-                    dismiss();
-                }
-            });
+        view.findViewById(R.id.dismiss).setOnClickListener(v -> dismiss());
         return view;
     }
 
@@ -123,34 +113,31 @@ public class AddIdentityDialogFragment extends AppCompatDialogFragment {
         new AlertDialog.Builder(activity)
             .setTitle(R.string.add_chan)
             .setView(dialogView)
-            .setPositiveButton(R.string.ok, new DialogInterface.OnClickListener() {
-                @Override
-                public void onClick(DialogInterface dialogInterface, int i) {
-                    TextView passphrase = (TextView) dialogView.findViewById(R.id.passphrase);
-                    Toast.makeText(ctx, R.string.toast_long_running_operation,
-                        Toast.LENGTH_SHORT).show();
-                    new AsyncTask<String, Void, BitmessageAddress>() {
-                        @Override
-                        protected BitmessageAddress doInBackground(String... args) {
-                            String pass = args[0];
-                            BitmessageAddress chan = bmc.createChan(pass);
-                            chan.setAlias(pass);
-                            bmc.addresses().save(chan);
-                            return chan;
-                        }
+            .setPositiveButton(R.string.ok, (dialogInterface, i) -> {
+                TextView passphrase = (TextView) dialogView.findViewById(R.id.passphrase);
+                Toast.makeText(ctx, R.string.toast_long_running_operation,
+                    Toast.LENGTH_SHORT).show();
+                new AsyncTask<String, Void, BitmessageAddress>() {
+                    @Override
+                    protected BitmessageAddress doInBackground(String... args) {
+                        String pass = args[0];
+                        BitmessageAddress chan = bmc.createChan(pass);
+                        chan.setAlias(pass);
+                        bmc.addresses().save(chan);
+                        return chan;
+                    }
 
-                        @Override
-                        protected void onPostExecute(BitmessageAddress chan) {
-                            Toast.makeText(ctx,
-                                R.string.toast_chan_created,
-                                Toast.LENGTH_SHORT).show();
-                            MainActivity mainActivity = MainActivity.getInstance();
-                            if (mainActivity != null) {
-                                mainActivity.addIdentityEntry(chan);
-                            }
+                    @Override
+                    protected void onPostExecute(BitmessageAddress chan) {
+                        Toast.makeText(ctx,
+                            R.string.toast_chan_created,
+                            Toast.LENGTH_SHORT).show();
+                        MainActivity mainActivity = MainActivity.getInstance();
+                        if (mainActivity != null) {
+                            mainActivity.addIdentityEntry(chan);
                         }
-                    }.execute(passphrase.getText().toString());
-                }
+                    }
+                }.execute(passphrase.getText().toString());
             })
             .setNegativeButton(R.string.cancel, null)
             .show();
diff --git a/app/src/main/java/ch/dissem/apps/abit/listener/WifiReceiver.java b/app/src/main/java/ch/dissem/apps/abit/listener/WifiReceiver.java
index ccd81ac..329d903 100644
--- a/app/src/main/java/ch/dissem/apps/abit/listener/WifiReceiver.java
+++ b/app/src/main/java/ch/dissem/apps/abit/listener/WifiReceiver.java
@@ -29,11 +29,13 @@ import ch.dissem.bitmessage.BitmessageContext;
 public class WifiReceiver extends BroadcastReceiver {
     @Override
     public void onReceive(Context ctx, Intent intent) {
-        if (Preferences.isWifiOnly(ctx)) {
-            BitmessageContext bmc = Singleton.getBitmessageContext(ctx);
+        if ("android.net.conn.CONNECTIVITY_CHANGE".equals(intent.getAction())) {
+            if (Preferences.isWifiOnly(ctx)) {
+                BitmessageContext bmc = Singleton.getBitmessageContext(ctx);
 
-            if (isConnectedToMeteredNetwork(ctx) && bmc.isRunning()) {
-                bmc.shutdown();
+                if (isConnectedToMeteredNetwork(ctx) && bmc.isRunning()) {
+                    bmc.shutdown();
+                }
             }
         }
     }
@@ -43,7 +45,7 @@ public class WifiReceiver extends BroadcastReceiver {
         if (netInfo == null || !netInfo.isConnectedOrConnecting()) {
             return false;
         }
-        switch (netInfo.getType()){
+        switch (netInfo.getType()) {
             case ConnectivityManager.TYPE_ETHERNET:
             case ConnectivityManager.TYPE_WIFI:
                 return false;
diff --git a/app/src/main/java/ch/dissem/apps/abit/notification/ErrorNotification.java b/app/src/main/java/ch/dissem/apps/abit/notification/ErrorNotification.java
index 0efdc66..e7a0654 100644
--- a/app/src/main/java/ch/dissem/apps/abit/notification/ErrorNotification.java
+++ b/app/src/main/java/ch/dissem/apps/abit/notification/ErrorNotification.java
@@ -31,7 +31,7 @@ import ch.dissem.apps.abit.R;
 public class ErrorNotification extends AbstractNotification {
     public static final int ERROR_NOTIFICATION_ID = 4;
 
-    private NotificationCompat.Builder builder;
+    private final NotificationCompat.Builder builder;
 
     public ErrorNotification(Context ctx) {
         super(ctx);
diff --git a/app/src/main/java/ch/dissem/apps/abit/pow/ServerPowEngine.java b/app/src/main/java/ch/dissem/apps/abit/pow/ServerPowEngine.java
index 1dd81bb..e8812ea 100644
--- a/app/src/main/java/ch/dissem/apps/abit/pow/ServerPowEngine.java
+++ b/app/src/main/java/ch/dissem/apps/abit/pow/ServerPowEngine.java
@@ -17,14 +17,12 @@
 package ch.dissem.apps.abit.pow;
 
 import android.content.Context;
-import android.support.annotation.NonNull;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
-import java.util.concurrent.ThreadFactory;
 
 import ch.dissem.apps.abit.service.Singleton;
 import ch.dissem.apps.abit.synchronization.SyncAdapter;
@@ -42,7 +40,7 @@ import static ch.dissem.bitmessage.utils.Singleton.cryptography;
  * @author Christian Basler
  */
 public class ServerPowEngine implements ProofOfWorkEngine, InternalContext
-        .ContextHolder {
+    .ContextHolder {
     private static final Logger LOG = LoggerFactory.getLogger(ServerPowEngine.class);
 
     private final Context ctx;
@@ -52,40 +50,34 @@ public class ServerPowEngine implements ProofOfWorkEngine, InternalContext
 
     public ServerPowEngine(Context ctx) {
         this.ctx = ctx;
-        pool = Executors.newCachedThreadPool(new ThreadFactory() {
-            @Override
-            public Thread newThread(@NonNull Runnable r) {
-                Thread thread = Executors.defaultThreadFactory().newThread(r);
-                thread.setPriority(Thread.MIN_PRIORITY);
-                return thread;
-            }
+        pool = Executors.newCachedThreadPool(r -> {
+            Thread thread = Executors.defaultThreadFactory().newThread(r);
+            thread.setPriority(Thread.MIN_PRIORITY);
+            return thread;
         });
     }
 
     @Override
     public void calculateNonce(final byte[] initialHash, final byte[] target, Callback callback) {
-        pool.execute(new Runnable() {
-            @Override
-            public void run() {
-                BitmessageAddress identity = Singleton.getIdentity(ctx);
-                if (identity == null) throw new RuntimeException("No Identity for calculating POW");
+        pool.execute(() -> {
+            BitmessageAddress identity = Singleton.getIdentity(ctx);
+            if (identity == null) throw new RuntimeException("No Identity for calculating POW");
 
-                ProofOfWorkRequest request = new ProofOfWorkRequest(identity, initialHash,
-                        CALCULATE, target);
-                SyncAdapter.startPowSync(ctx);
-                try {
-                    CryptoCustomMessage<ProofOfWorkRequest> cryptoMsg = new CryptoCustomMessage<>
-                            (request);
-                    cryptoMsg.signAndEncrypt(
-                            identity,
-                            cryptography().createPublicKey(identity.getPublicDecryptionKey())
-                    );
-                    context.getNetworkHandler().send(
-                            Preferences.getTrustedNode(ctx), Preferences.getTrustedNodePort(ctx),
-                            cryptoMsg);
-                } catch (Exception e) {
-                    LOG.error(e.getMessage(), e);
-                }
+            ProofOfWorkRequest request = new ProofOfWorkRequest(identity, initialHash,
+                CALCULATE, target);
+            SyncAdapter.startPowSync(ctx);
+            try {
+                CryptoCustomMessage<ProofOfWorkRequest> cryptoMsg = new CryptoCustomMessage<>
+                    (request);
+                cryptoMsg.signAndEncrypt(
+                    identity,
+                    cryptography().createPublicKey(identity.getPublicDecryptionKey())
+                );
+                context.getNetworkHandler().send(
+                    Preferences.getTrustedNode(ctx), Preferences.getTrustedNodePort(ctx),
+                    cryptoMsg);
+            } catch (Exception e) {
+                LOG.error(e.getMessage(), e);
             }
         });
     }
diff --git a/app/src/main/java/ch/dissem/apps/abit/repository/AndroidAddressRepository.java b/app/src/main/java/ch/dissem/apps/abit/repository/AndroidAddressRepository.java
index b585aeb..5557112 100644
--- a/app/src/main/java/ch/dissem/apps/abit/repository/AndroidAddressRepository.java
+++ b/app/src/main/java/ch/dissem/apps/abit/repository/AndroidAddressRepository.java
@@ -169,14 +169,10 @@ public class AndroidAddressRepository implements AddressRepository {
 
     @Override
     public void save(BitmessageAddress address) {
-        try {
-            if (exists(address)) {
-                update(address);
-            } else {
-                insert(address);
-            }
-        } catch (IOException e) {
-            LOG.error(e.getMessage(), e);
+        if (exists(address)) {
+            update(address);
+        } else {
+            insert(address);
         }
     }
 
@@ -191,7 +187,7 @@ public class AndroidAddressRepository implements AddressRepository {
         }
     }
 
-    private void update(BitmessageAddress address) throws IOException {
+    private void update(BitmessageAddress address) {
         try {
             SQLiteDatabase db = sql.getWritableDatabase();
             // Create a new map of values, where column names are the keys
@@ -224,7 +220,7 @@ public class AndroidAddressRepository implements AddressRepository {
         }
     }
 
-    private void insert(BitmessageAddress address) throws IOException {
+    private void insert(BitmessageAddress address) {
         try {
             SQLiteDatabase db = sql.getWritableDatabase();
             // Create a new map of values, where column names are the keys
diff --git a/app/src/main/java/ch/dissem/apps/abit/repository/AndroidMessageRepository.java b/app/src/main/java/ch/dissem/apps/abit/repository/AndroidMessageRepository.java
index f430f66..8c6aad8 100644
--- a/app/src/main/java/ch/dissem/apps/abit/repository/AndroidMessageRepository.java
+++ b/app/src/main/java/ch/dissem/apps/abit/repository/AndroidMessageRepository.java
@@ -275,14 +275,12 @@ public class AndroidMessageRepository extends AbstractMessageRepository {
             db.setTransactionSuccessful();
         } catch (SQLiteConstraintException e) {
             LOG.trace(e.getMessage(), e);
-        } catch (IOException e) {
-            LOG.error(e.getMessage(), e);
         } finally {
             db.endTransaction();
         }
     }
 
-    private void insert(SQLiteDatabase db, Plaintext message) throws IOException {
+    private void insert(SQLiteDatabase db, Plaintext message) {
         ContentValues values = new ContentValues();
         values.put(COLUMN_IV, message.getInventoryVector() == null ? null : message
             .getInventoryVector().getHash());
@@ -302,7 +300,7 @@ public class AndroidMessageRepository extends AbstractMessageRepository {
         message.setId(id);
     }
 
-    private void update(SQLiteDatabase db, Plaintext message) throws IOException {
+    private void update(SQLiteDatabase db, Plaintext message) {
         ContentValues values = new ContentValues();
         values.put(COLUMN_IV, message.getInventoryVector() == null ? null : message
             .getInventoryVector().getHash());
diff --git a/app/src/main/java/ch/dissem/apps/abit/repository/SqlHelper.java b/app/src/main/java/ch/dissem/apps/abit/repository/SqlHelper.java
index 87a2bc2..5e6a68c 100644
--- a/app/src/main/java/ch/dissem/apps/abit/repository/SqlHelper.java
+++ b/app/src/main/java/ch/dissem/apps/abit/repository/SqlHelper.java
@@ -27,10 +27,10 @@ import ch.dissem.apps.abit.util.Assets;
  */
 public class SqlHelper extends SQLiteOpenHelper {
     // If you change the database schema, you must increment the database version.
-    public static final int DATABASE_VERSION = 5;
-    public static final String DATABASE_NAME = "jabit.db";
+    private static final int DATABASE_VERSION = 5;
+    private static final String DATABASE_NAME = "jabit.db";
 
-    protected final Context ctx;
+    private final Context ctx;
 
     public SqlHelper(Context ctx) {
         super(ctx, DATABASE_NAME, null, DATABASE_VERSION);
@@ -65,7 +65,7 @@ public class SqlHelper extends SQLiteOpenHelper {
         }
     }
 
-    protected void executeMigration(SQLiteDatabase db, String name) {
+    private void executeMigration(SQLiteDatabase db, String name) {
         for (String statement : Assets.readSqlStatements(ctx, "db/migration/" + name + ".sql")) {
             db.execSQL(statement);
         }
diff --git a/app/src/main/java/ch/dissem/apps/abit/service/ProofOfWorkService.java b/app/src/main/java/ch/dissem/apps/abit/service/ProofOfWorkService.java
index c01f5c3..3b41df7 100644
--- a/app/src/main/java/ch/dissem/apps/abit/service/ProofOfWorkService.java
+++ b/app/src/main/java/ch/dissem/apps/abit/service/ProofOfWorkService.java
@@ -37,9 +37,9 @@ import static ch.dissem.apps.abit.notification.ProofOfWorkNotification.ONGOING_N
  */
 public class ProofOfWorkService extends Service {
     // Object to use as a thread-safe lock
-    private static ProofOfWorkEngine engine = new MultiThreadedPOWEngine();
-    private static boolean calculating;
+    private static final ProofOfWorkEngine engine = new MultiThreadedPOWEngine();
     private static final Queue<PowItem> queue = new LinkedList<>();
+    private static boolean calculating;
     private ProofOfWorkNotification notification;
 
     @Override
diff --git a/app/src/main/java/ch/dissem/apps/abit/service/ServicePowEngine.java b/app/src/main/java/ch/dissem/apps/abit/service/ServicePowEngine.java
index 7211dcf..b7f0a84 100644
--- a/app/src/main/java/ch/dissem/apps/abit/service/ServicePowEngine.java
+++ b/app/src/main/java/ch/dissem/apps/abit/service/ServicePowEngine.java
@@ -38,14 +38,14 @@ public class ServicePowEngine implements ProofOfWorkEngine {
     private final Context ctx;
 
     private static final Object lock = new Object();
-    private Queue<PowItem> queue = new LinkedList<>();
+    private final Queue<PowItem> queue = new LinkedList<>();
     private PowBinder service;
 
     public ServicePowEngine(Context ctx) {
         this.ctx = ctx;
     }
 
-    private ServiceConnection connection = new ServiceConnection() {
+    private final ServiceConnection connection = new ServiceConnection() {
         @Override
         public void onServiceConnected(ComponentName name, IBinder service) {
             synchronized (lock) {
@@ -75,4 +75,4 @@ public class ServicePowEngine implements ProofOfWorkEngine {
             }
         }
     }
-}
\ No newline at end of file
+}
diff --git a/app/src/main/java/ch/dissem/apps/abit/util/Preferences.java b/app/src/main/java/ch/dissem/apps/abit/util/Preferences.java
index 0653559..e5d52ba 100644
--- a/app/src/main/java/ch/dissem/apps/abit/util/Preferences.java
+++ b/app/src/main/java/ch/dissem/apps/abit/util/Preferences.java
@@ -20,9 +20,6 @@ import android.content.Context;
 import android.content.SharedPreferences;
 import android.preference.PreferenceManager;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 import java.io.IOException;
 import java.net.InetAddress;