diff --git a/app/src/main/java/org/linphone/LinphoneManager.java b/app/src/main/java/org/linphone/LinphoneManager.java
index 398e99f60..ea480aeb4 100644
--- a/app/src/main/java/org/linphone/LinphoneManager.java
+++ b/app/src/main/java/org/linphone/LinphoneManager.java
@@ -522,7 +522,7 @@ public class LinphoneManager implements SensorEventListener {
 
                 if (mCore.limeX3DhAvailable()) {
                     String url = mCore.getLimeX3DhServerUrl();
-                    if (url == null || url.length() == 0) {
+                    if (url == null || url.isEmpty()) {
                         url = getString(R.string.default_lime_x3dh_server_url);
                         Log.i("[Manager] Setting LIME X3Dh server url to default value: " + url);
                         mCore.setLimeX3DhServerUrl(url);
diff --git a/app/src/main/java/org/linphone/chat/ChatMessagesFragment.java b/app/src/main/java/org/linphone/chat/ChatMessagesFragment.java
index b509d1a2a..ccf17b10b 100644
--- a/app/src/main/java/org/linphone/chat/ChatMessagesFragment.java
+++ b/app/src/main/java/org/linphone/chat/ChatMessagesFragment.java
@@ -716,7 +716,7 @@ public class ChatMessagesFragment extends Fragment
         Core core = LinphoneManager.getCore();
         if (mRemoteSipAddress == null
                 || mRemoteSipUri == null
-                || mRemoteSipUri.length() == 0
+                || mRemoteSipUri.isEmpty()
                 || core == null) {
             // TODO error
             return;
@@ -768,7 +768,7 @@ public class ChatMessagesFragment extends Fragment
                         });
             }
 
-            if (mParticipants.size() == 0) {
+            if (mParticipants.isEmpty()) {
                 // Contact not found
                 String displayName = LinphoneUtils.getAddressDisplayName(mRemoteParticipantAddress);
                 mRoomLabel.setText(displayName);
@@ -1229,7 +1229,7 @@ public class ChatMessagesFragment extends Fragment
         }
 
         mRemoteComposing.setVisibility(View.VISIBLE);
-        if (composing.size() == 0) {
+        if (composing.isEmpty()) {
             mRemoteComposing.setVisibility(View.GONE);
         } else if (composing.size() == 1) {
             mRemoteComposing.setText(
diff --git a/app/src/main/java/org/linphone/chat/ChatRoomCreationFragment.java b/app/src/main/java/org/linphone/chat/ChatRoomCreationFragment.java
index d53479a1e..d59e189ff 100644
--- a/app/src/main/java/org/linphone/chat/ChatRoomCreationFragment.java
+++ b/app/src/main/java/org/linphone/chat/ChatRoomCreationFragment.java
@@ -485,7 +485,7 @@ public class ChatRoomCreationFragment extends Fragment
     }
 
     private void updateLayout() {
-        if (mParticipants.size() != 0) {
+        if (!mParticipants.isEmpty()) {
             mSearchAdapter.setContactsSelectedList(mParticipants);
             updateList();
             updateListSelected();
diff --git a/app/src/main/java/org/linphone/chat/DevicesAdapter.java b/app/src/main/java/org/linphone/chat/DevicesAdapter.java
index 1a8da4005..e95ecd25d 100644
--- a/app/src/main/java/org/linphone/chat/DevicesAdapter.java
+++ b/app/src/main/java/org/linphone/chat/DevicesAdapter.java
@@ -199,7 +199,7 @@ class DevicesAdapter extends BaseExpandableListAdapter {
 
     @Override
     public int getGroupCount() {
-        if (mParticipants.size() == 0) return 0;
+        if (mParticipants.isEmpty()) return 0;
         return mOnlyDisplayChildsAsGroups
                 ? mParticipants.get(0).getDevices().length
                 : mParticipants.size();
@@ -207,7 +207,7 @@ class DevicesAdapter extends BaseExpandableListAdapter {
 
     @Override
     public int getChildrenCount(int groupPosition) {
-        if (mParticipants.size() == 0) return 0;
+        if (mParticipants.isEmpty()) return 0;
         return mOnlyDisplayChildsAsGroups
                 ? 0
                 : mParticipants.get(groupPosition).getDevices().length;
@@ -215,7 +215,7 @@ class DevicesAdapter extends BaseExpandableListAdapter {
 
     @Override
     public Object getGroup(int groupPosition) {
-        if (mParticipants.size() == 0) return null;
+        if (mParticipants.isEmpty()) return null;
         return mOnlyDisplayChildsAsGroups
                 ? mParticipants.get(0).getDevices()[groupPosition]
                 : mParticipants.get(groupPosition);
@@ -223,7 +223,7 @@ class DevicesAdapter extends BaseExpandableListAdapter {
 
     @Override
     public Object getChild(int groupPosition, int childPosition) {
-        if (mParticipants.size() == 0) return null;
+        if (mParticipants.isEmpty()) return null;
         return mParticipants.get(groupPosition).getDevices()[childPosition];
     }
 
diff --git a/app/src/main/java/org/linphone/compatibility/ApiTwentyFivePlus.java b/app/src/main/java/org/linphone/compatibility/ApiTwentyFivePlus.java
index c12f4715c..60802b676 100644
--- a/app/src/main/java/org/linphone/compatibility/ApiTwentyFivePlus.java
+++ b/app/src/main/java/org/linphone/compatibility/ApiTwentyFivePlus.java
@@ -37,6 +37,7 @@ import org.linphone.core.ChatRoomCapabilities;
 import org.linphone.core.tools.Log;
 import org.linphone.settings.LinphonePreferences;
 import org.linphone.utils.LinphoneShortcutManager;
+import org.linphone.utils.LinphoneUtils;
 
 @TargetApi(25)
 class ApiTwentyFivePlus {
@@ -50,13 +51,8 @@ class ApiTwentyFivePlus {
         ArrayList<ShortcutInfo> shortcuts = new ArrayList<>();
 
         ChatRoom[] rooms = LinphoneManager.getCore().getChatRooms();
-        ArrayList<ChatRoom> notEmptyOneToOneRooms = new ArrayList<>();
-        for (ChatRoom room : rooms) {
-            if (room.hasCapability(ChatRoomCapabilities.OneToOne.toInt())
-                    && room.getHistorySize() > 0) {
-                notEmptyOneToOneRooms.add(room);
-            }
-        }
+        ArrayList<ChatRoom> notEmptyOneToOneRooms =
+                LinphoneUtils.removeEmptyOneToOneChatRooms(rooms);
         Collections.sort(
                 notEmptyOneToOneRooms,
                 new Comparator<ChatRoom>() {
diff --git a/app/src/main/java/org/linphone/contacts/ContactsFragment.java b/app/src/main/java/org/linphone/contacts/ContactsFragment.java
index 7249d3317..655e6ab16 100644
--- a/app/src/main/java/org/linphone/contacts/ContactsFragment.java
+++ b/app/src/main/java/org/linphone/contacts/ContactsFragment.java
@@ -144,10 +144,10 @@ public class ContactsFragment extends Fragment
             }
         } else {
             if (!mOnlyDisplayLinphoneContacts
-                    && ContactsManager.getInstance().getContacts().size() == 0) {
+                    && ContactsManager.getInstance().getContacts().isEmpty()) {
                 mNoContact.setVisibility(View.VISIBLE);
             } else if (mOnlyDisplayLinphoneContacts
-                    && ContactsManager.getInstance().getSIPContacts().size() == 0) {
+                    && ContactsManager.getInstance().getSIPContacts().isEmpty()) {
                 mNoSipContact.setVisibility(View.VISIBLE);
             }
         }
@@ -268,7 +268,7 @@ public class ContactsFragment extends Fragment
 
     private void searchContacts(String search) {
         boolean isEditionEnabled = false;
-        if (search == null || search.length() == 0) {
+        if (search == null || search.isEmpty()) {
             changeContactsAdapter();
             return;
         }
diff --git a/app/src/main/java/org/linphone/contacts/ContactsManager.java b/app/src/main/java/org/linphone/contacts/ContactsManager.java
index 3e678204c..84b68b2f1 100644
--- a/app/src/main/java/org/linphone/contacts/ContactsManager.java
+++ b/app/src/main/java/org/linphone/contacts/ContactsManager.java
@@ -264,7 +264,7 @@ public class ContactsManager extends ContentObserver implements FriendListListen
             }
         }
 
-        if (mContext != null && getContacts().size() == 0 && hasReadContactsAccess()) {
+        if (mContext != null && getContacts().isEmpty() && hasReadContactsAccess()) {
             fetchContactsAsync();
         }
     }
diff --git a/app/src/main/java/org/linphone/contacts/LinphoneContact.java b/app/src/main/java/org/linphone/contacts/LinphoneContact.java
index 892ecd055..3f5a9565a 100644
--- a/app/src/main/java/org/linphone/contacts/LinphoneContact.java
+++ b/app/src/main/java/org/linphone/contacts/LinphoneContact.java
@@ -125,7 +125,7 @@ public class LinphoneContact extends AndroidContact
     }
 
     public void setFirstNameAndLastName(String fn, String ln, boolean commitChanges) {
-        if (fn != null && fn.length() == 0 && ln != null && ln.length() == 0) return;
+        if (fn != null && fn.isEmpty() && ln != null && ln.isEmpty()) return;
         if (fn != null && fn.equals(mFirstName) && ln != null && ln.equals(mLastName)) return;
 
         if (commitChanges) {
diff --git a/app/src/main/java/org/linphone/purchase/InAppPurchaseActivity.java b/app/src/main/java/org/linphone/purchase/InAppPurchaseActivity.java
index 9a138b98e..2b03793dd 100644
--- a/app/src/main/java/org/linphone/purchase/InAppPurchaseActivity.java
+++ b/app/src/main/java/org/linphone/purchase/InAppPurchaseActivity.java
@@ -108,7 +108,7 @@ public class InAppPurchaseActivity extends Activity
 
     public List<Purchasable> getPurchasedItems() {
 
-        if (mPurchasedItems == null || mPurchasedItems.size() == 0) {
+        if (mPurchasedItems == null || mPurchasedItems.isEmpty()) {
             Log.w("nul");
         }
         return mPurchasedItems;
@@ -145,7 +145,7 @@ public class InAppPurchaseActivity extends Activity
     public void onPurchasedItemsQueryFinished(ArrayList<Purchasable> items) {
         mPurchasedItems = items;
 
-        if (items == null || items.size() == 0) {
+        if (items == null || items.isEmpty()) {
             mInAppPurchaseHelper.getAvailableItemsForPurchaseAsync();
         } else {
             for (Purchasable purchasedItem : mPurchasedItems) {
diff --git a/app/src/main/java/org/linphone/settings/LinphonePreferences.java b/app/src/main/java/org/linphone/settings/LinphonePreferences.java
index 0cc4946b5..a60f87b92 100644
--- a/app/src/main/java/org/linphone/settings/LinphonePreferences.java
+++ b/app/src/main/java/org/linphone/settings/LinphonePreferences.java
@@ -199,7 +199,7 @@ public class LinphonePreferences {
 
     public String getRingtone(String defaultRingtone) {
         String ringtone = getConfig().getString("app", "ringtone", defaultRingtone);
-        if (ringtone == null || ringtone.length() == 0) ringtone = defaultRingtone;
+        if (ringtone == null || ringtone.isEmpty()) ringtone = defaultRingtone;
         return ringtone;
     }
 
@@ -817,7 +817,7 @@ public class LinphonePreferences {
 
     public void setRemoteProvisioningUrl(String url) {
         if (getLc() == null) return;
-        if (url != null && url.length() == 0) {
+        if (url != null && url.isEmpty()) {
             url = null;
         }
         getLc().setProvisioningUri(url);