diff --git a/build.gradle b/build.gradle
index 4822d4bd377f..922e75d9115b 100644
--- a/build.gradle
+++ b/build.gradle
@@ -212,7 +212,7 @@ android {
 
     android.applicationVariants.all { variant ->
         String variantName = variant.name
-        String capVariantName = variantName.substring(0, 1).toUpperCase() + variantName.substring(1);
+        String capVariantName = variantName.substring(0, 1).toUpperCase() + variantName.substring(1)
         tasks.register("spotbugs${capVariantName}", SpotBugsTask) {
             ignoreFailures = false
             effort = "max"
@@ -273,7 +273,6 @@ dependencies {
     implementation 'pl.droidsonroids.gif:android-gif-drawable:1.2.15'
     implementation 'com.github.tobiaskaminsky:qrcodescanner:0.1.2.2' // 'com.github.blikoon:QRCodeScanner:0.1.2'
     implementation 'com.google.android:flexbox:1.1.0'
-
     implementation 'org.parceler:parceler-api:1.1.12'
     annotationProcessor 'org.parceler:parceler:1.1.12'
     implementation('com.github.bumptech.glide:glide:3.7.0') {
@@ -282,6 +281,19 @@ dependencies {
     implementation 'com.caverock:androidsvg:1.3'
     implementation 'androidx.annotation:annotation:1.0.2'
     implementation 'com.google.code.gson:gson:2.8.5'
+    implementation 'org.jetbrains:annotations:17.0.0'
+
+    spotbugsPlugins 'com.h3xstream.findsecbugs:findsecbugs-plugin:1.9.0'
+    spotbugsPlugins 'com.mebigfatguy.fb-contrib:fb-contrib:7.4.3'
+
+    implementation 'com.google.dagger:dagger:2.22.1'
+    implementation 'com.google.dagger:dagger-android:2.22.1'
+    implementation 'com.google.dagger:dagger-android-support:2.22.1'
+    annotationProcessor 'com.google.dagger:dagger-compiler:2.22.1'
+    annotationProcessor 'com.google.dagger:dagger-android-processor:2.22.1'
+
+    compileOnly "org.projectlombok:lombok:1.18.6"
+    annotationProcessor "org.projectlombok:lombok:1.18.6"
 
     // dependencies for local unit tests
     testImplementation 'junit:junit:4.12'
@@ -302,26 +314,13 @@ dependencies {
     // Espresso core
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.1'
     androidTestImplementation 'androidx.test.espresso:espresso-contrib:3.1.1'
+    androidTestImplementation 'org.mockito:mockito-core:2.27.0'
     // UIAutomator - for cross-app UI tests, and to grant screen is turned on in Espresso tests
     // androidTestImplementation 'androidx.test.uiautomator:uiautomator:2.2.0'
     // fix conflict in dependencies; see http://g.co/androidstudio/app-test-app-conflict for details
     //androidTestImplementation "com.android.support:support-annotations:${supportLibraryVersion}"
-    implementation 'org.jetbrains:annotations:17.0.0'
-
-    compileOnly "org.projectlombok:lombok:1.18.6"
-    annotationProcessor "org.projectlombok:lombok:1.18.6"
-
     androidTestImplementation 'tools.fastlane:screengrab:1.2.0'
 
-    spotbugsPlugins 'com.h3xstream.findsecbugs:findsecbugs-plugin:1.9.0'
-    spotbugsPlugins 'com.mebigfatguy.fb-contrib:fb-contrib:7.4.3'
-
-    implementation 'com.google.dagger:dagger:2.22.1'
-    implementation 'com.google.dagger:dagger-android:2.22.1'
-    implementation 'com.google.dagger:dagger-android-support:2.22.1'
-    annotationProcessor 'com.google.dagger:dagger-compiler:2.22.1'
-    annotationProcessor 'com.google.dagger:dagger-android-processor:2.22.1'
-
 //    jacocoAnt "org.jacoco:org.jacoco.ant:${jacocoVersion}"
 //    jacocoAgent "org.jacoco:org.jacoco.agent:${jacocoVersion}"
 //    androidJacocoAgent "org.jacoco:org.jacoco.agent:${jacocoVersion}"
diff --git a/src/androidTest/java/com/owncloud/android/util/ErrorMessageAdapterIT.java b/src/androidTest/java/com/owncloud/android/util/ErrorMessageAdapterIT.java
new file mode 100644
index 000000000000..32867ac4d4a0
--- /dev/null
+++ b/src/androidTest/java/com/owncloud/android/util/ErrorMessageAdapterIT.java
@@ -0,0 +1,59 @@
+/*
+ *   ownCloud Android client application
+ *
+ *   @author David A. Velasco
+ *   Copyright (C) 2016 ownCloud Inc.
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License version 2,
+ *   as published by the Free Software Foundation.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+
+package com.owncloud.android.util;
+
+import android.accounts.Account;
+import android.content.res.Resources;
+
+import com.owncloud.android.MainApp;
+import com.owncloud.android.lib.common.operations.RemoteOperationResult;
+import com.owncloud.android.operations.RemoveFileOperation;
+import com.owncloud.android.utils.ErrorMessageAdapter;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+import androidx.test.platform.app.InstrumentationRegistry;
+
+import static junit.framework.TestCase.assertEquals;
+
+@RunWith(AndroidJUnit4.class)
+public class ErrorMessageAdapterIT {
+    private final static String PATH_TO_DELETE = "/path/to/a.file";
+    private final static String EXPECTED_ERROR_MESSAGE = "You are not permitted to delete this file";
+    private final static String ACCOUNT_TYPE = "nextcloud";
+
+    @Test
+    public void getErrorCauseMessageForForbiddenRemoval() {
+        Resources resources = InstrumentationRegistry.getInstrumentation().getTargetContext().getResources();
+        Account account = new Account("name", ACCOUNT_TYPE);
+
+        String errorMessage = ErrorMessageAdapter.getErrorCauseMessage(
+            new RemoteOperationResult(RemoteOperationResult.ResultCode.FORBIDDEN),
+            new RemoveFileOperation(PATH_TO_DELETE, false, account, false, MainApp.getAppContext()),
+            resources
+        );
+
+        assertEquals(EXPECTED_ERROR_MESSAGE, errorMessage);
+    }
+}
diff --git a/src/test/java/com/owncloud/android/utils/TestSorting.java b/src/androidTest/java/com/owncloud/android/util/TestSorting.java
similarity index 99%
rename from src/test/java/com/owncloud/android/utils/TestSorting.java
rename to src/androidTest/java/com/owncloud/android/util/TestSorting.java
index 65fae56fdf17..acee99b89275 100644
--- a/src/test/java/com/owncloud/android/utils/TestSorting.java
+++ b/src/androidTest/java/com/owncloud/android/util/TestSorting.java
@@ -1,4 +1,4 @@
-package com.owncloud.android.utils;
+package com.owncloud.android.util;
 
 import com.owncloud.android.datamodel.OCFile;
 
diff --git a/src/main/java/com/owncloud/android/authentication/AuthenticatorActivity.java b/src/main/java/com/owncloud/android/authentication/AuthenticatorActivity.java
index 658040abe4d9..19dd37a173a0 100644
--- a/src/main/java/com/owncloud/android/authentication/AuthenticatorActivity.java
+++ b/src/main/java/com/owncloud/android/authentication/AuthenticatorActivity.java
@@ -1091,9 +1091,8 @@ private void hidePassword() {
     public void onOkClick() {
         // this check should be unnecessary
         if (mServerInfo.mVersion == null ||
-                !mServerInfo.mVersion.isVersionValid() ||
-                mServerInfo.mBaseUrl == null ||
-                mServerInfo.mBaseUrl.length() == 0) {
+            !mServerInfo.mVersion.isVersionValid() ||
+            TextUtils.isEmpty(mServerInfo.mBaseUrl)) {
             mServerStatusIcon = R.drawable.ic_alert;
             mServerStatusText = getResources().getString(R.string.auth_wtf_reenter_URL);
             showServerStatus();
@@ -1898,8 +1897,7 @@ private void doOnResumeAndBound() {
             mOperationsServiceBinder.dispatchResultIfFinished((int) mWaitingForOpId, this);
         }
 
-        if (!webViewLoginMethod && mHostUrlInput.getText() != null && mHostUrlInput.getText().length() > 0
-                && !mServerIsChecked) {
+        if (!webViewLoginMethod && !TextUtils.isEmpty(mHostUrlInput.getText()) && !mServerIsChecked) {
             checkOcServer();
         }
     }
diff --git a/src/main/java/com/owncloud/android/authentication/AuthenticatorUrlUtils.java b/src/main/java/com/owncloud/android/authentication/AuthenticatorUrlUtils.java
index e20b53993d50..dea14c410de2 100644
--- a/src/main/java/com/owncloud/android/authentication/AuthenticatorUrlUtils.java
+++ b/src/main/java/com/owncloud/android/authentication/AuthenticatorUrlUtils.java
@@ -22,6 +22,7 @@
 package com.owncloud.android.authentication;
 
 import android.content.Context;
+import android.text.TextUtils;
 
 import com.owncloud.android.lib.resources.status.OwnCloudVersion;
 
@@ -64,7 +65,7 @@ public static String normalizeUrlSuffix(String url) {
     public static String normalizeUrl(String url, boolean sslWhenUnprefixed) {
         String normalizedUrl = url;
 
-        if (normalizedUrl != null && normalizedUrl.length() > 0) {
+        if (!TextUtils.isEmpty(normalizedUrl)) {
             normalizedUrl = normalizedUrl.trim();
 
             if (!normalizedUrl.toLowerCase(Locale.ROOT).startsWith(HTTP_PROTOCOL) &&
diff --git a/src/main/java/com/owncloud/android/datamodel/OCFile.java b/src/main/java/com/owncloud/android/datamodel/OCFile.java
index 3779f0ef7907..afaf7334b645 100644
--- a/src/main/java/com/owncloud/android/datamodel/OCFile.java
+++ b/src/main/java/com/owncloud/android/datamodel/OCFile.java
@@ -28,6 +28,8 @@
 import android.net.Uri;
 import android.os.Parcel;
 import android.os.Parcelable;
+import android.text.TextUtils;
+
 import androidx.annotation.NonNull;
 import androidx.core.content.FileProvider;
 import com.owncloud.android.R;
@@ -115,7 +117,7 @@ public class OCFile implements Parcelable, Comparable<OCFile>, ServerFileInterfa
     public OCFile(String path) {
         resetData();
         needsUpdatingWhileSaving = false;
-        if (path == null || path.length() <= 0 || !path.startsWith(PATH_SEPARATOR)) {
+        if (TextUtils.isEmpty(path) || !path.startsWith(PATH_SEPARATOR)) {
             throw new IllegalArgumentException("Trying to create a OCFile with a non valid remote path: " + path);
         }
         remotePath = path;
@@ -262,7 +264,7 @@ public boolean isDown() {
      * @return true if it is
      */
     public boolean existsOnDevice() {
-        if (localPath != null && localPath.length() > 0) {
+        if (!TextUtils.isEmpty(localPath)) {
             return new File(localPath).exists();
         }
         return false;
@@ -283,7 +285,7 @@ public String getStoragePath() {
      * @return A URI to the local copy of the file, or NULL if not stored in the device
      */
     public Uri getStorageUri() {
-        if (localPath == null || localPath.length() == 0) {
+        if (TextUtils.isEmpty(localPath)) {
             return null;
         }
         if (localUri == null) {
@@ -297,7 +299,7 @@ public Uri getStorageUri() {
 
 
     public Uri getLegacyExposedFileUri() {
-        if (localPath == null || localPath.length() == 0) {
+        if (TextUtils.isEmpty(localPath)) {
             return null;
         }
 
@@ -312,7 +314,7 @@ public Uri getLegacyExposedFileUri() {
         Partly disabled because not all apps understand paths that we get via this method for now
      */
     public Uri getExposedFileUri(Context context) {
-        if (localPath == null || localPath.length() == 0) {
+        if (TextUtils.isEmpty(localPath)) {
             return null;
         }
         if (exposedFileUri == null) {
@@ -360,8 +362,7 @@ public String getFileName() {
      */
     public void setFileName(String name) {
         Log_OC.d(TAG, "OCFile name changing from " + remotePath);
-        if (name != null && name.length() > 0 && !name.contains(PATH_SEPARATOR) &&
-            !ROOT_PATH.equals(remotePath)) {
+        if (!TextUtils.isEmpty(name) && !name.contains(PATH_SEPARATOR) && !ROOT_PATH.equals(remotePath)) {
             String parent = new File(this.getRemotePath()).getParent();
             parent = parent.endsWith(PATH_SEPARATOR) ? parent : parent + PATH_SEPARATOR;
             remotePath = parent + name;
@@ -468,7 +469,7 @@ public void setEtagOnServer(String etag) {
     }
 
     public long getLocalModificationTimestamp() {
-        if (localPath != null && localPath.length() > 0) {
+        if (!TextUtils.isEmpty(localPath)) {
             File f = new File(localPath);
             return f.lastModified();
         }
@@ -479,7 +480,7 @@ public long getLocalModificationTimestamp() {
      * @return 'True' if the file is hidden
      */
     public boolean isHidden() {
-        return getFileName().length() > 0 && getFileName().charAt(0) == '.';
+        return !TextUtils.isEmpty(getFileName()) && getFileName().charAt(0) == '.';
     }
 
     /**
@@ -492,7 +493,7 @@ public String getLocalId() {
     }
 
     public boolean isInConflict() {
-        return etagInConflict != null && !"".equals(etagInConflict);
+        return !TextUtils.isEmpty(etagInConflict);
     }
 
     public boolean isSharedWithMe() {
diff --git a/src/main/java/com/owncloud/android/operations/DetectAuthenticationMethodOperation.java b/src/main/java/com/owncloud/android/operations/DetectAuthenticationMethodOperation.java
index 165f4189eec3..f20efbb5580a 100644
--- a/src/main/java/com/owncloud/android/operations/DetectAuthenticationMethodOperation.java
+++ b/src/main/java/com/owncloud/android/operations/DetectAuthenticationMethodOperation.java
@@ -22,6 +22,7 @@
 
 import android.content.Context;
 import android.net.Uri;
+import android.text.TextUtils;
 
 import com.owncloud.android.lib.common.OwnCloudClient;
 import com.owncloud.android.lib.common.operations.RemoteOperation;
@@ -89,8 +90,7 @@ protected RemoteOperationResult run(OwnCloudClient client) {
         // try to access the root folder, following redirections but not SAML SSO redirections
         result = operation.execute(client);
         String redirectedLocation = result.getRedirectedLocation(); 
-        while (redirectedLocation != null && redirectedLocation.length() > 0 && 
-                !result.isIdPRedirection()) {
+        while (!TextUtils.isEmpty(redirectedLocation) && !result.isIdPRedirection()) {
             client.setBaseUri(Uri.parse(result.getRedirectedLocation()));
             result = operation.execute(client);
             redirectedLocation = result.getRedirectedLocation();
diff --git a/src/main/java/com/owncloud/android/operations/DownloadFileOperation.java b/src/main/java/com/owncloud/android/operations/DownloadFileOperation.java
index 6842c2f8053b..73c9e5a3fe22 100644
--- a/src/main/java/com/owncloud/android/operations/DownloadFileOperation.java
+++ b/src/main/java/com/owncloud/android/operations/DownloadFileOperation.java
@@ -23,6 +23,7 @@
 
 import android.accounts.Account;
 import android.content.Context;
+import android.text.TextUtils;
 import android.webkit.MimeTypeMap;
 
 import com.owncloud.android.datamodel.DecryptedFolderMetadata;
@@ -110,7 +111,7 @@ public String getRemotePath() {
 
     public String getMimeType() {
         String mimeType = file.getMimeType();
-        if (mimeType == null || mimeType.length() <= 0) {
+        if (TextUtils.isEmpty(mimeType)) {
             try {
                 mimeType = MimeTypeMap.getSingleton()
                     .getMimeTypeFromExtension(
diff --git a/src/main/java/com/owncloud/android/operations/RenameFileOperation.java b/src/main/java/com/owncloud/android/operations/RenameFileOperation.java
index fa8b86e04c3a..cde479ad3cd7 100644
--- a/src/main/java/com/owncloud/android/operations/RenameFileOperation.java
+++ b/src/main/java/com/owncloud/android/operations/RenameFileOperation.java
@@ -21,6 +21,8 @@
 
 package com.owncloud.android.operations;
 
+import android.text.TextUtils;
+
 import com.owncloud.android.datamodel.FileDataStorageManager;
 import com.owncloud.android.datamodel.OCFile;
 import com.owncloud.android.lib.common.OwnCloudClient;
@@ -157,7 +159,7 @@ private void saveLocalFile() {
      */
     private boolean isValidNewName() throws IOException {
         // check tricky names
-        if (newName == null || newName.length() <= 0 || newName.contains(File.separator)) {
+        if (TextUtils.isEmpty(newName) || newName.contains(File.separator)) {
             return false;
         }
         // create a test file
diff --git a/src/main/java/com/owncloud/android/operations/SynchronizeFileOperation.java b/src/main/java/com/owncloud/android/operations/SynchronizeFileOperation.java
index 7b0b5041dee7..72e4a1ecbe61 100644
--- a/src/main/java/com/owncloud/android/operations/SynchronizeFileOperation.java
+++ b/src/main/java/com/owncloud/android/operations/SynchronizeFileOperation.java
@@ -24,6 +24,7 @@
 import android.accounts.Account;
 import android.content.Context;
 import android.content.Intent;
+import android.text.TextUtils;
 
 import com.owncloud.android.datamodel.OCFile;
 import com.owncloud.android.files.services.FileDownloader;
@@ -204,7 +205,7 @@ protected RemoteOperationResult run(OwnCloudClient client) {
             if (mServerFile != null) {
                 /// check changes in server and local file
                 boolean serverChanged;
-                if (mLocalFile.getEtag() == null || mLocalFile.getEtag().length() == 0) {
+                if (TextUtils.isEmpty(mLocalFile.getEtag())) {
                     // file uploaded (null) or downloaded ("") before upgrade to version 1.8.0; check the old condition
                     serverChanged = mServerFile.getModificationTimestamp() !=
                             mLocalFile.getModificationTimestampAtLastSyncForData();
diff --git a/src/main/java/com/owncloud/android/operations/SynchronizeFolderOperation.java b/src/main/java/com/owncloud/android/operations/SynchronizeFolderOperation.java
index 32cf1605873c..e9751fbc6f49 100644
--- a/src/main/java/com/owncloud/android/operations/SynchronizeFolderOperation.java
+++ b/src/main/java/com/owncloud/android/operations/SynchronizeFolderOperation.java
@@ -23,6 +23,7 @@
 import android.accounts.Account;
 import android.content.Context;
 import android.content.Intent;
+import android.text.TextUtils;
 import android.util.Log;
 
 import com.owncloud.android.datamodel.FileDataStorageManager;
@@ -482,7 +483,7 @@ public void cancel() {
 
     public String getFolderPath() {
         String path = mLocalFolder.getStoragePath();
-        if (path != null && path.length() > 0) {
+        if (!TextUtils.isEmpty(path)) {
             return path;
         }
         return FileStorageUtils.getDefaultSavePathFor(mAccount.name, mLocalFolder);
diff --git a/src/main/java/com/owncloud/android/operations/UploadFileOperation.java b/src/main/java/com/owncloud/android/operations/UploadFileOperation.java
index 74b509a867b5..579a9185dc3c 100644
--- a/src/main/java/com/owncloud/android/operations/UploadFileOperation.java
+++ b/src/main/java/com/owncloud/android/operations/UploadFileOperation.java
@@ -27,6 +27,7 @@
 import android.content.Context;
 import android.net.Uri;
 import android.os.Build;
+import android.text.TextUtils;
 import android.util.Log;
 
 import com.evernote.android.job.JobRequest;
@@ -153,7 +154,7 @@ public class UploadFileOperation extends SyncOperation {
     public static OCFile obtainNewOCFileToUpload(String remotePath, String localPath, String mimeType) {
 
         // MIME type
-        if (mimeType == null || mimeType.length() <= 0) {
+        if (TextUtils.isEmpty(mimeType)) {
             mimeType = MimeTypeUtil.getBestMimeTypeByFilename(localPath);
         }
 
@@ -163,7 +164,7 @@ public static OCFile obtainNewOCFileToUpload(String remotePath, String localPath
         newFile.setLastSyncDateForData(0);
 
         // size
-        if (localPath != null && localPath.length() > 0) {
+        if (!TextUtils.isEmpty(localPath)) {
             File localFile = new File(localPath);
             newFile.setFileLength(localFile.length());
             newFile.setLastSyncDateForData(localFile.lastModified());
@@ -192,7 +193,7 @@ public UploadFileOperation(UploadsStorageManager uploadsStorageManager,
         if (upload == null) {
             throw new IllegalArgumentException("Illegal NULL file in UploadFileOperation creation");
         }
-        if (upload.getLocalPath() == null || upload.getLocalPath().length() <= 0) {
+        if (TextUtils.isEmpty(upload.getLocalPath())) {
             throw new IllegalArgumentException(
                     "Illegal file in UploadFileOperation; storage path invalid: "
                             + upload.getLocalPath());
diff --git a/src/main/java/com/owncloud/android/services/OperationsService.java b/src/main/java/com/owncloud/android/services/OperationsService.java
index dcaf56af8345..118b6c109bee 100644
--- a/src/main/java/com/owncloud/android/services/OperationsService.java
+++ b/src/main/java/com/owncloud/android/services/OperationsService.java
@@ -36,6 +36,7 @@
 import android.os.Looper;
 import android.os.Message;
 import android.os.Process;
+import android.text.TextUtils;
 import android.util.Pair;
 
 import com.owncloud.android.MainApp;
@@ -455,8 +456,7 @@ private void nextOperation() {
                             );
                         } else {
                             OwnCloudCredentials credentials = null;
-                            if (mLastTarget.mCookie != null &&
-                                    mLastTarget.mCookie.length() > 0) {
+                            if (!TextUtils.isEmpty(mLastTarget.mCookie)) {
                                 // just used for GetUserName
                                 // TODO refactor to run GetUserName as AsyncTask in the context of
                                 // AuthenticatorActivity
@@ -558,7 +558,7 @@ private Pair<Target, RemoteOperation> newOperation(Intent operationIntent) {
                     case ACTION_CREATE_SHARE_VIA_LINK:
                         remotePath = operationIntent.getStringExtra(EXTRA_REMOTE_PATH);
                         password = operationIntent.getStringExtra(EXTRA_SHARE_PASSWORD);
-                        if (remotePath.length() > 0) {
+                        if (!TextUtils.isEmpty(remotePath)) {
                             operation = new CreateShareViaLinkOperation(remotePath, password);
                         }
                         break;
@@ -567,7 +567,7 @@ private Pair<Target, RemoteOperation> newOperation(Intent operationIntent) {
                         remotePath = operationIntent.getStringExtra(EXTRA_REMOTE_PATH);
                         shareId = operationIntent.getLongExtra(EXTRA_SHARE_ID, -1);
 
-                        if (remotePath != null && remotePath.length() > 0) {
+                        if (!TextUtils.isEmpty(remotePath)) {
                             UpdateShareViaLinkOperation updateLinkOperation = new UpdateShareViaLinkOperation(remotePath);
 
                             password = operationIntent.getStringExtra(EXTRA_SHARE_PASSWORD);
@@ -616,7 +616,7 @@ private Pair<Target, RemoteOperation> newOperation(Intent operationIntent) {
                         String shareeName = operationIntent.getStringExtra(EXTRA_SHARE_WITH);
                         shareType = (ShareType) operationIntent.getSerializableExtra(EXTRA_SHARE_TYPE);
                         int permissions = operationIntent.getIntExtra(EXTRA_SHARE_PERMISSIONS, -1);
-                        if (remotePath.length() > 0) {
+                        if (!TextUtils.isEmpty(remotePath)) {
                             operation = new CreateShareWithShareeOperation(remotePath, shareeName, shareType,
                                     permissions);
                         }
@@ -627,7 +627,7 @@ private Pair<Target, RemoteOperation> newOperation(Intent operationIntent) {
                         shareType = (ShareType) operationIntent.getSerializableExtra(EXTRA_SHARE_TYPE);
                         String shareWith = operationIntent.getStringExtra(EXTRA_SHARE_WITH);
 
-                        if (remotePath.length() > 0) {
+                        if (!TextUtils.isEmpty(remotePath)) {
                             operation = new UnshareOperation(remotePath, shareType, shareWith, this);
                         }
                         break;
diff --git a/src/main/java/com/owncloud/android/ui/activity/FileDisplayActivity.java b/src/main/java/com/owncloud/android/ui/activity/FileDisplayActivity.java
index 6ad33c85cce5..01d3cbdfb2d9 100644
--- a/src/main/java/com/owncloud/android/ui/activity/FileDisplayActivity.java
+++ b/src/main/java/com/owncloud/android/ui/activity/FileDisplayActivity.java
@@ -1989,7 +1989,7 @@ private void onCreateShareViaLinkOperationFinish(CreateShareViaLinkOperation ope
             // Detect Failure (403) --> maybe needs password
             String password = operation.getPassword();
             if (result.getCode() == RemoteOperationResult.ResultCode.SHARE_FORBIDDEN    &&
-                    (password == null || password.length() == 0)                        &&
+                    TextUtils.isEmpty(password)                                         &&
                     getCapabilities().getFilesSharingPublicEnabled().isUnknown()) {
                 // Was tried without password, but not sure that it's optional.
 
diff --git a/src/main/java/com/owncloud/android/ui/activity/PassCodeActivity.java b/src/main/java/com/owncloud/android/ui/activity/PassCodeActivity.java
index 5d50058e4255..60063d52fee9 100644
--- a/src/main/java/com/owncloud/android/ui/activity/PassCodeActivity.java
+++ b/src/main/java/com/owncloud/android/ui/activity/PassCodeActivity.java
@@ -26,6 +26,7 @@
 import android.graphics.PorterDuff;
 import android.os.Bundle;
 import android.text.Editable;
+import android.text.TextUtils;
 import android.text.TextWatcher;
 import android.view.KeyEvent;
 import android.view.View;
@@ -204,7 +205,7 @@ protected void setTextListeners() {
 
     private void onPassCodeEditTextFocusChange(final int passCodeIndex) {
         for (int i = 0; i < passCodeIndex; i++) {
-            if ("".equals(mPassCodeEditTexts[i].getText().toString())) {
+            if (TextUtils.isEmpty(mPassCodeEditTexts[i].getText())) {
                 mPassCodeEditTexts[i].requestFocus();
                 break;
             }
diff --git a/src/main/java/com/owncloud/android/ui/activity/ReceiveExternalFilesActivity.java b/src/main/java/com/owncloud/android/ui/activity/ReceiveExternalFilesActivity.java
index 683426418b61..9b86cb0fca43 100755
--- a/src/main/java/com/owncloud/android/ui/activity/ReceiveExternalFilesActivity.java
+++ b/src/main/java/com/owncloud/android/ui/activity/ReceiveExternalFilesActivity.java
@@ -43,6 +43,7 @@
 import android.os.Handler;
 import android.os.Looper;
 import android.os.Parcelable;
+import android.text.TextUtils;
 import android.text.format.DateFormat;
 import android.view.LayoutInflater;
 import android.view.Menu;
@@ -750,7 +751,7 @@ private void populateDirectoryList() {
         boolean notRoot = mParents.size() > 1;
 
         if (actionBar != null) {
-            if ("".equals(current_dir)) {
+            if (TextUtils.isEmpty(current_dir)) {
                 ThemeUtils.setColoredTitle(actionBar, R.string.uploader_top_message, this);
             } else {
                 ThemeUtils.setColoredTitle(actionBar, current_dir, this);
diff --git a/src/main/java/com/owncloud/android/ui/activity/ShareActivity.java b/src/main/java/com/owncloud/android/ui/activity/ShareActivity.java
index edfd9373cf27..ee8f04b41fb5 100644
--- a/src/main/java/com/owncloud/android/ui/activity/ShareActivity.java
+++ b/src/main/java/com/owncloud/android/ui/activity/ShareActivity.java
@@ -25,6 +25,7 @@
 import android.content.Intent;
 import android.net.Uri;
 import android.os.Bundle;
+import android.text.TextUtils;
 
 import com.google.android.material.snackbar.Snackbar;
 import com.owncloud.android.R;
@@ -348,7 +349,7 @@ private void onCreateShareViaLinkOperationFinish(CreateShareViaLinkOperation ope
             // Detect Failure (403) --> maybe needs password
             String password = operation.getPassword();
             if (result.getCode() == RemoteOperationResult.ResultCode.SHARE_FORBIDDEN    &&
-                    (password == null || password.length() == 0)                        &&
+                    TextUtils.isEmpty(password)                                         &&
                     getCapabilities().getFilesSharingPublicEnabled().isUnknown()) {
                     // Was tried without password, but not sure that it's optional.
 
diff --git a/src/main/java/com/owncloud/android/ui/dialog/CreateFolderDialogFragment.java b/src/main/java/com/owncloud/android/ui/dialog/CreateFolderDialogFragment.java
index 8963fedcfdc6..1f7dc2feb9ab 100644
--- a/src/main/java/com/owncloud/android/ui/dialog/CreateFolderDialogFragment.java
+++ b/src/main/java/com/owncloud/android/ui/dialog/CreateFolderDialogFragment.java
@@ -24,6 +24,7 @@
 import android.content.DialogInterface;
 import android.graphics.PorterDuff;
 import android.os.Bundle;
+import android.text.TextUtils;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.Window;
@@ -124,7 +125,7 @@ public void onClick(DialogInterface dialog, int which) {
                     ((TextView)(getDialog().findViewById(R.id.user_input)))
                         .getText().toString().trim();
 
-            if (newFolderName.length() <= 0) {
+            if (TextUtils.isEmpty(newFolderName)) {
                 DisplayUtils.showSnackMessage(getActivity(), R.string.filename_empty);
                 return;
             }
diff --git a/src/main/java/com/owncloud/android/ui/dialog/RenameFileDialogFragment.java b/src/main/java/com/owncloud/android/ui/dialog/RenameFileDialogFragment.java
index 9909a5f1263a..0957d13ba5b0 100644
--- a/src/main/java/com/owncloud/android/ui/dialog/RenameFileDialogFragment.java
+++ b/src/main/java/com/owncloud/android/ui/dialog/RenameFileDialogFragment.java
@@ -30,6 +30,7 @@
 import android.content.DialogInterface;
 import android.graphics.PorterDuff;
 import android.os.Bundle;
+import android.text.TextUtils;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.Window;
@@ -139,7 +140,7 @@ public void onClick(DialogInterface dialog, int which) {
                 ((TextView)(getDialog().findViewById(R.id.user_input)))
                     .getText().toString().trim();
 
-            if (newFileName.length() <= 0) {
+            if (TextUtils.isEmpty(newFileName)) {
                 DisplayUtils.showSnackMessage(getActivity(), R.string.filename_empty);
                 return;
             }
diff --git a/src/main/java/com/owncloud/android/ui/dialog/SharePasswordDialogFragment.java b/src/main/java/com/owncloud/android/ui/dialog/SharePasswordDialogFragment.java
index 535a70f2bf40..cb8b76e174e7 100644
--- a/src/main/java/com/owncloud/android/ui/dialog/SharePasswordDialogFragment.java
+++ b/src/main/java/com/owncloud/android/ui/dialog/SharePasswordDialogFragment.java
@@ -24,6 +24,7 @@
 import android.content.DialogInterface;
 import android.graphics.PorterDuff;
 import android.os.Bundle;
+import android.text.TextUtils;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
@@ -152,7 +153,7 @@ public void onClick(DialogInterface dialog, int which) {
         if (which == AlertDialog.BUTTON_POSITIVE) {
             String password = ((TextView) (getDialog().findViewById(R.id.share_password))).getText().toString();
 
-            if (password.length() <= 0) {
+            if (TextUtils.isEmpty(password)) {
                 DisplayUtils.showSnackMessage(
                         getActivity().findViewById(android.R.id.content),
                         R.string.share_link_empty_password
diff --git a/src/main/java/com/owncloud/android/ui/dialog/SyncedFolderPreferencesDialogFragment.java b/src/main/java/com/owncloud/android/ui/dialog/SyncedFolderPreferencesDialogFragment.java
index abd2132dca28..b590d60e8214 100644
--- a/src/main/java/com/owncloud/android/ui/dialog/SyncedFolderPreferencesDialogFragment.java
+++ b/src/main/java/com/owncloud/android/ui/dialog/SyncedFolderPreferencesDialogFragment.java
@@ -27,6 +27,7 @@
 import android.graphics.Typeface;
 import android.os.Build;
 import android.os.Bundle;
+import android.text.TextUtils;
 import android.text.style.StyleSpan;
 import android.view.LayoutInflater;
 import android.view.View;
@@ -203,7 +204,7 @@ private void setupDialogElements(View view) {
         // Set values
         setEnabled(mSyncedFolder.getEnabled());
 
-        if (mSyncedFolder.getLocalPath() != null && mSyncedFolder.getLocalPath().length() > 0) {
+        if (!TextUtils.isEmpty(mSyncedFolder.getLocalPath())) {
             mLocalFolderPath.setText(
                     DisplayUtils.createTextWithSpan(
                             String.format(
@@ -216,7 +217,7 @@ private void setupDialogElements(View view) {
             mLocalFolderSummary.setText(R.string.choose_local_folder);
         }
 
-        if (mSyncedFolder.getLocalPath() != null && mSyncedFolder.getLocalPath().length() > 0) {
+        if (!TextUtils.isEmpty(mSyncedFolder.getLocalPath())) {
             mRemoteFolderSummary.setText(mSyncedFolder.getRemotePath());
         } else {
             mRemoteFolderSummary.setText(R.string.choose_remote_folder);
diff --git a/src/main/java/com/owncloud/android/ui/helpers/FileOperationsHelper.java b/src/main/java/com/owncloud/android/ui/helpers/FileOperationsHelper.java
index 806aaf23dea1..789cf4a98227 100755
--- a/src/main/java/com/owncloud/android/ui/helpers/FileOperationsHelper.java
+++ b/src/main/java/com/owncloud/android/ui/helpers/FileOperationsHelper.java
@@ -39,6 +39,7 @@
 import android.os.Build;
 import android.os.Environment;
 import android.provider.MediaStore;
+import android.text.TextUtils;
 import android.util.Log;
 import android.view.View;
 import android.webkit.MimeTypeMap;
@@ -431,7 +432,7 @@ public void shareFileViaLink(OCFile file, String password) {
             Intent service = new Intent(mFileActivity, OperationsService.class);
             service.setAction(OperationsService.ACTION_CREATE_SHARE_VIA_LINK);
             service.putExtra(OperationsService.EXTRA_ACCOUNT, mFileActivity.getAccount());
-            if (password != null && password.length() > 0) {
+            if (!TextUtils.isEmpty(password)) {
                 service.putExtra(OperationsService.EXTRA_SHARE_PASSWORD, password);
             }
             service.putExtra(OperationsService.EXTRA_REMOTE_PATH, file.getRemotePath());
diff --git a/src/main/java/com/owncloud/android/ui/preview/PreviewImageActivity.java b/src/main/java/com/owncloud/android/ui/preview/PreviewImageActivity.java
index 308d37eb7ac0..5b729de7db66 100644
--- a/src/main/java/com/owncloud/android/ui/preview/PreviewImageActivity.java
+++ b/src/main/java/com/owncloud/android/ui/preview/PreviewImageActivity.java
@@ -32,6 +32,7 @@
 import android.content.ServiceConnection;
 import android.os.Bundle;
 import android.os.IBinder;
+import android.text.TextUtils;
 import android.view.MenuItem;
 import android.view.View;
 
@@ -222,7 +223,7 @@ public void onRemoteOperationFinish(RemoteOperation operation, RemoteOperationRe
                 // Detect Failure (403) --> maybe needs password
                 String password = op.getPassword();
                 if (result.getCode() == RemoteOperationResult.ResultCode.SHARE_FORBIDDEN &&
-                    (password == null || password.length() == 0) &&
+                    TextUtils.isEmpty(password) &&
                     getCapabilities().getFilesSharingPublicEnabled().isUnknown()) {
                     // Was tried without password, but not sure that it's optional.
 
diff --git a/src/main/java/com/owncloud/android/utils/ClipboardUtil.java b/src/main/java/com/owncloud/android/utils/ClipboardUtil.java
index ac697da6d003..8c6f62756773 100644
--- a/src/main/java/com/owncloud/android/utils/ClipboardUtil.java
+++ b/src/main/java/com/owncloud/android/utils/ClipboardUtil.java
@@ -24,6 +24,7 @@
 import android.content.ClipData;
 import android.content.ClipboardManager;
 import android.content.Context;
+import android.text.TextUtils;
 import android.widget.Toast;
 
 import com.owncloud.android.R;
@@ -43,7 +44,7 @@ public static void copyToClipboard(Activity activity, String text) {
     }
 
     public static void copyToClipboard(Activity activity, String text, boolean showToast) {
-        if (text != null && text.length() > 0) {
+        if (!TextUtils.isEmpty(text)) {
             try {
                 ClipData clip = ClipData.newPlainText(
                         activity.getString(
diff --git a/src/main/java/com/owncloud/android/utils/ErrorMessageAdapter.java b/src/main/java/com/owncloud/android/utils/ErrorMessageAdapter.java
index fc4125345ff1..30a74bbb8656 100644
--- a/src/main/java/com/owncloud/android/utils/ErrorMessageAdapter.java
+++ b/src/main/java/com/owncloud/android/utils/ErrorMessageAdapter.java
@@ -22,6 +22,7 @@
 package com.owncloud.android.utils;
 
 import android.content.res.Resources;
+import android.text.TextUtils;
 
 import com.owncloud.android.R;
 import com.owncloud.android.lib.common.operations.RemoteOperation;
@@ -77,11 +78,11 @@ public static String getErrorCauseMessage(
     ) {
         String message = getSpecificMessageForResultAndOperation(result, operation, res);
 
-        if (message == null || message.length() <= 0) {
+        if (TextUtils.isEmpty(message)) {
             message = getCommonMessageForResult(result, res);
         }
 
-        if (message == null || message.length() <= 0) {
+        if (TextUtils.isEmpty(message)) {
             message = getGenericErrorMessageForOperation(operation, res);
         }
 
@@ -434,7 +435,7 @@ private static String getCommonMessageForResult(RemoteOperationResult result, Re
 
             }
 
-            else if (result.getHttpPhrase() != null && result.getHttpPhrase().length() > 0) {
+            else if (!TextUtils.isEmpty(result.getHttpPhrase())) {
                 // last chance: error message from server
                 message = result.getHttpPhrase();
             }
diff --git a/src/test/java/com/owncloud/android/utils/ErrorMessageAdapterUnitTest.java b/src/test/java/com/owncloud/android/utils/ErrorMessageAdapterUnitTest.java
deleted file mode 100644
index 1a9b171f79c9..000000000000
--- a/src/test/java/com/owncloud/android/utils/ErrorMessageAdapterUnitTest.java
+++ /dev/null
@@ -1,84 +0,0 @@
-/*
- *   ownCloud Android client application
- *
- *   @author David A. Velasco
- *   Copyright (C) 2016 ownCloud Inc.
- *
- *   This program is free software: you can redistribute it and/or modify
- *   it under the terms of the GNU General Public License version 2,
- *   as published by the Free Software Foundation.
- *
- *   This program is distributed in the hope that it will be useful,
- *   but WITHOUT ANY WARRANTY; without even the implied warranty of
- *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *   GNU General Public License for more details.
- *
- *   You should have received a copy of the GNU General Public License
- *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
- *
- */
-
-
-package com.owncloud.android.utils;
-
-import android.accounts.Account;
-import android.content.res.Resources;
-
-import com.owncloud.android.MainApp;
-import com.owncloud.android.R;
-import com.owncloud.android.lib.common.operations.RemoteOperationResult;
-import com.owncloud.android.operations.RemoveFileOperation;
-
-import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.mockito.Mock;
-import org.mockito.runners.MockitoJUnitRunner;
-
-import static org.hamcrest.CoreMatchers.is;
-import static org.hamcrest.MatcherAssert.assertThat;
-import static org.mockito.Mockito.when;
-
-/**
- * Local unit test, to be run out of Android emulator or device.
- *
- * At the moment, it's a sample to validate the automatic test environment, in the scope of local unit tests with
- * mock Android dependencies.
- *
- * Don't take it as an example of completeness.
- *
- * See http://developer.android.com/intl/es/training/testing/unit-testing/local-unit-tests.html .
- */
-@RunWith(MockitoJUnitRunner.class)
-public class ErrorMessageAdapterUnitTest {
-
-    private final static String MOCK_FORBIDDEN_PERMISSIONS = "You do not have permission %s";
-    private final static String MOCK_TO_DELETE = "to delete this file";
-    private final static String PATH_TO_DELETE = "/path/to/a.file";
-    private final static String EXPECTED_ERROR_MESSAGE = "You do not have permission to delete this file";
-    private final static String ACCOUNT_TYPE = "nextcloud";
-
-    @Mock
-    private Resources mMockResources;
-
-    @Test
-    public void getErrorCauseMessageForForbiddenRemoval() {
-        // Given a mocked set of resources passed to the object under test...
-        when(mMockResources.getString(R.string.forbidden_permissions))
-            .thenReturn(MOCK_FORBIDDEN_PERMISSIONS);
-        when(mMockResources.getString(R.string.forbidden_permissions_delete))
-            .thenReturn(MOCK_TO_DELETE);
-
-        Account account = new Account("name", ACCOUNT_TYPE);
-
-        // ... when method under test is called ...
-        String errorMessage = ErrorMessageAdapter.getErrorCauseMessage(
-            new RemoteOperationResult(RemoteOperationResult.ResultCode.FORBIDDEN),
-                new RemoveFileOperation(PATH_TO_DELETE, false, account, false, MainApp.getAppContext()),
-            mMockResources
-        );
-
-        // ... then the result should be the expected one.
-        assertThat(errorMessage, is(EXPECTED_ERROR_MESSAGE));
-
-    }
-}