Use Collection.isEmpty() (#10172)

15 files changed, 45 insertions, 40 deletions

diff --git a/client/src/main/java/com/vaadin/client/componentlocator/ComponentLocator.java b/client/src/main/java/com/vaadin/client/componentlocator/ComponentLocator.java
index 9669131651..e0dbfca6b3 100644
--- a/client/src/main/java/com/vaadin/client/componentlocator/ComponentLocator.java
+++ b/client/src/main/java/com/vaadin/client/componentlocator/ComponentLocator.java
@@ -152,7 +152,7 @@ public class ComponentLocator {
         for (LocatorStrategy strategy : locatorStrategies) {
             if (strategy.validatePath(path)) {
                 List<Element> elements = strategy.getElementsByPath(path);
-                if (elements.size() > 0) {
+                if (!elements.isEmpty()) {
                     for (Element e : elements) {
                         jsElements.push(e);
                     }
@@ -184,7 +184,7 @@ public class ComponentLocator {
             if (strategy.validatePath(path)) {
                 List<Element> elements = strategy
                         .getElementsByPathStartingAt(path, root);
-                if (elements.size() > 0) {
+                if (!elements.isEmpty()) {
                     for (Element e : elements) {
                         jsElements.push(e);
                     }
diff --git a/client/src/main/java/com/vaadin/client/componentlocator/VaadinFinderLocatorStrategy.java b/client/src/main/java/com/vaadin/client/componentlocator/VaadinFinderLocatorStrategy.java
index b650702c08..2c2ff5707c 100644
--- a/client/src/main/java/com/vaadin/client/componentlocator/VaadinFinderLocatorStrategy.java
+++ b/client/src/main/java/com/vaadin/client/componentlocator/VaadinFinderLocatorStrategy.java
@@ -118,7 +118,7 @@ public class VaadinFinderLocatorStrategy implements LocatorStrategy {
             path.add(pathFragment);
         }
 
-        if (path.size() == 0) {
+        if (path.isEmpty()) {
             // If we didn't find a single element, return null..
             return null;
         }
@@ -277,7 +277,7 @@ public class VaadinFinderLocatorStrategy implements LocatorStrategy {
     public List<Element> getElementsByPath(String path) {
         List<SelectorPredicate> postFilters = SelectorPredicate
                 .extractPostFilterPredicates(path);
-        if (postFilters.size() > 0) {
+        if (!postFilters.isEmpty()) {
             path = path.substring(1, path.lastIndexOf(')'));
         }
 
@@ -347,7 +347,7 @@ public class VaadinFinderLocatorStrategy implements LocatorStrategy {
             Element root) {
         List<SelectorPredicate> postFilters = SelectorPredicate
                 .extractPostFilterPredicates(path);
-        if (postFilters.size() > 0) {
+        if (!postFilters.isEmpty()) {
             path = path.substring(1, path.lastIndexOf(')'));
         }
 
@@ -617,7 +617,7 @@ public class VaadinFinderLocatorStrategy implements LocatorStrategy {
         List<Integer> widgetTags = new ArrayList<>();
         widgetTags.addAll(getTags(widgetName));
 
-        if (widgetTags.size() == 0) {
+        if (widgetTags.isEmpty()) {
             widgetTags.addAll(getTags("com.vaadin.ui." + widgetName));
         }
 
@@ -631,7 +631,7 @@ public class VaadinFinderLocatorStrategy implements LocatorStrategy {
             final String simpleName = getSimpleClassName(name);
             final String fullName = getFullClassName(name);
 
-            if (widgetTags.size() > 0) {
+            if (!widgetTags.isEmpty()) {
                 Integer[] foundTags = client.getConfiguration()
                         .getTagsForServerSideClassName(fullName);
                 for (int tag : foundTags) {
diff --git a/client/src/main/java/com/vaadin/client/connectors/grid/GridDragSourceConnector.java b/client/src/main/java/com/vaadin/client/connectors/grid/GridDragSourceConnector.java
index bc94293e78..3414133a9d 100644
--- a/client/src/main/java/com/vaadin/client/connectors/grid/GridDragSourceConnector.java
+++ b/client/src/main/java/com/vaadin/client/connectors/grid/GridDragSourceConnector.java
@@ -141,7 +141,7 @@ public class GridDragSourceConnector extends DragSourceExtensionConnector {
         draggedItems = getDraggedRows(nativeEvent);
 
         // Ignore event if there are no items dragged
-        if (draggedItems.size() == 0) {
+        if (draggedItems.isEmpty()) {
             return;
         }
 
@@ -214,9 +214,12 @@ public class GridDragSourceConnector extends DragSourceExtensionConnector {
             final Element selectionColumnCell = getGrid().getSelectionColumn()
                     .isPresent()
                     // -1 is used when even selection column is not frozen
-                    && frozenColumnCount != -1 ? draggedRowElement
-                            .removeChild(draggedRowElement.getFirstChild())
-                            .cast() : null;
+                    && frozenColumnCount != -1
+                            ? draggedRowElement
+                                    .removeChild(
+                                            draggedRowElement.getFirstChild())
+                                    .cast()
+                            : null;
 
             final List<String> frozenCellsTransforms = new ArrayList<>();
             for (int i = 0; i < getGrid().getColumnCount(); i++) {
@@ -331,7 +334,7 @@ public class GridDragSourceConnector extends DragSourceExtensionConnector {
             return;
         }
         // Ignore event if there are no items dragged
-        if (draggedItems != null && draggedItems.size() > 0) {
+        if (draggedItems != null && !draggedItems.isEmpty()) {
             super.onDragEnd(event);
         }
 
@@ -448,8 +451,8 @@ public class GridDragSourceConnector extends DragSourceExtensionConnector {
      * @return Stream of dragged table row elements.
      */
     private Stream<TableRowElement> getDraggedRowElementStream() {
-        return draggedItems.stream()
-                .map(row -> ((AbstractRemoteDataSource<JsonObject>) gridConnector
+        return draggedItems.stream().map(
+                row -> ((AbstractRemoteDataSource<JsonObject>) gridConnector
                         .getDataSource()).indexOf(row))
                 .map(getGridBody()::getRowElement);
     }
diff --git a/client/src/main/java/com/vaadin/client/debug/internal/AnalyzeLayoutsPanel.java b/client/src/main/java/com/vaadin/client/debug/internal/AnalyzeLayoutsPanel.java
index a1bcae5524..88a85cb764 100644
--- a/client/src/main/java/com/vaadin/client/debug/internal/AnalyzeLayoutsPanel.java
+++ b/client/src/main/java/com/vaadin/client/debug/internal/AnalyzeLayoutsPanel.java
@@ -83,17 +83,17 @@ public class AnalyzeLayoutsPanel extends FlowPanel {
         Set<ComponentConnector> zeroWidthComponents = new HashSet<>();
         findZeroSizeComponents(zeroHeightComponents, zeroWidthComponents,
                 ac.getUIConnector());
-        if (zeroHeightComponents.size() > 0 || zeroWidthComponents.size() > 0) {
+        if (!zeroHeightComponents.isEmpty() || !zeroWidthComponents.isEmpty()) {
             add(new HTML("<h4> Client side notifications</h4>"
                     + " <em>The following relative sized components were "
                     + "rendered to a zero size container on the client side."
                     + " Note that these are not necessarily invalid "
                     + "states, but reported here as they might be.</em>"));
-            if (zeroHeightComponents.size() > 0) {
+            if (!zeroHeightComponents.isEmpty()) {
                 add(new HTML("<p><strong>Vertically zero size:</strong></p>"));
                 printClientSideDetectedIssues(zeroHeightComponents, ac);
             }
-            if (zeroWidthComponents.size() > 0) {
+            if (!zeroWidthComponents.isEmpty()) {
                 add(new HTML(
                         "<p><strong>Horizontally zero size:</strong></p>"));
                 printClientSideDetectedIssues(zeroWidthComponents, ac);
diff --git a/client/src/main/java/com/vaadin/client/debug/internal/InfoSection.java b/client/src/main/java/com/vaadin/client/debug/internal/InfoSection.java
index c0efe72b78..9e688349ad 100644
--- a/client/src/main/java/com/vaadin/client/debug/internal/InfoSection.java
+++ b/client/src/main/java/com/vaadin/client/debug/internal/InfoSection.java
@@ -142,7 +142,7 @@ public class InfoSection implements Section {
         clear();
         List<ApplicationConnection> apps = ApplicationConfiguration
                 .getRunningApplications();
-        if (apps.size() == 0) {
+        if (apps.isEmpty()) {
             // try again in a while
             refresher.schedule(1000);
         } else {
diff --git a/client/src/main/java/com/vaadin/client/debug/internal/SelectorPath.java b/client/src/main/java/com/vaadin/client/debug/internal/SelectorPath.java
index 268924b143..07da3fbd4a 100644
--- a/client/src/main/java/com/vaadin/client/debug/internal/SelectorPath.java
+++ b/client/src/main/java/com/vaadin/client/debug/internal/SelectorPath.java
@@ -80,7 +80,7 @@ public class SelectorPath {
         String tmpPath = path;
         List<SelectorPredicate> postFilters = SelectorPredicate
                 .extractPostFilterPredicates(path);
-        if (postFilters.size() > 0) {
+        if (!postFilters.isEmpty()) {
             tmpPath = tmpPath.substring(1, tmpPath.lastIndexOf(')'));
             if (tmpPath.contains("#")) {
                 // FIXME: SubParts should be handled.
diff --git a/client/src/main/java/com/vaadin/client/extensions/FileDropTargetConnector.java b/client/src/main/java/com/vaadin/client/extensions/FileDropTargetConnector.java
index 2d4048bc78..6d9a5c3bba 100644
--- a/client/src/main/java/com/vaadin/client/extensions/FileDropTargetConnector.java
+++ b/client/src/main/java/com/vaadin/client/extensions/FileDropTargetConnector.java
@@ -80,7 +80,7 @@ public class FileDropTargetConnector extends DropTargetExtensionConnector {
      */
     private void uploadNextFile() {
         Scheduler.get().scheduleDeferred(() -> {
-            if (!uploading && uploadUrls.size() > 0) {
+            if (!uploading && !uploadUrls.isEmpty()) {
                 uploading = true;
                 String nextId = uploadUrls.keySet().stream().findAny().get();
 
@@ -124,7 +124,7 @@ public class FileDropTargetConnector extends DropTargetExtensionConnector {
             }
 
             // Request a list of upload URLs for the dropped files
-            if (fileParams.size() > 0) {
+            if (!fileParams.isEmpty()) {
                 getRpcProxy(FileDropTargetRpc.class).drop(fileParams);
             }
 
@@ -197,7 +197,8 @@ public class FileDropTargetConnector extends DropTargetExtensionConnector {
         protected FileUploadXHR() {
         }
 
-        public final native void postFile(File file) /*-{
+        public final native void postFile(File file)
+        /*-{
             this.setRequestHeader('Content-Type', 'multipart/form-data');
             this.send(file);
         }-*/;
diff --git a/client/src/main/java/com/vaadin/client/extensions/ResponsiveConnector.java b/client/src/main/java/com/vaadin/client/extensions/ResponsiveConnector.java
index 7115c1e3c6..3af049c635 100644
--- a/client/src/main/java/com/vaadin/client/extensions/ResponsiveConnector.java
+++ b/client/src/main/java/com/vaadin/client/extensions/ResponsiveConnector.java
@@ -107,7 +107,7 @@ public class ResponsiveConnector extends AbstractExtensionConnector
         selectors.append('.').append(primaryStyle);
 
         if (target.getState().styles != null
-                && target.getState().styles.size() > 0) {
+                && !target.getState().styles.isEmpty()) {
             for (String style : target.getState().styles) {
                 selectors.append(",.").append(style);
                 selectors.append(",.").append(primaryStyle).append('.')
diff --git a/client/src/main/java/com/vaadin/client/ui/VComboBox.java b/client/src/main/java/com/vaadin/client/ui/VComboBox.java
index 37b94ef8d6..5d98fd25d6 100644
--- a/client/src/main/java/com/vaadin/client/ui/VComboBox.java
+++ b/client/src/main/java/com/vaadin/client/ui/VComboBox.java
@@ -1067,7 +1067,7 @@ public class VComboBox extends Composite implements Field, KeyDownHandler,
          * Gets the preferred height of the menu including pageItemsCount items.
          */
         String getPreferredHeight(int pageItemsCount) {
-            if (currentSuggestions.size() > 0) {
+            if (!currentSuggestions.isEmpty()) {
                 final int pixels = getPreferredHeight()
                         / currentSuggestions.size() * pageItemsCount;
                 return pixels + "px";
@@ -1260,7 +1260,7 @@ public class VComboBox extends Composite implements Field, KeyDownHandler,
          */
         int getItemOffsetHeight() {
             List<MenuItem> items = getItems();
-            return items != null && items.size() > 0
+            return items != null && !items.isEmpty()
                     ? items.get(0).getOffsetHeight()
                     : 0;
         }
@@ -1270,7 +1270,7 @@ public class VComboBox extends Composite implements Field, KeyDownHandler,
          */
         int getItemOffsetWidth() {
             List<MenuItem> items = getItems();
-            return items != null && items.size() > 0
+            return items != null && !items.isEmpty()
                     ? items.get(0).getOffsetWidth()
                     : 0;
         }
diff --git a/client/src/main/java/com/vaadin/client/ui/VDragAndDropWrapper.java b/client/src/main/java/com/vaadin/client/ui/VDragAndDropWrapper.java
index 20a0afcf0d..0202cdf430 100644
--- a/client/src/main/java/com/vaadin/client/ui/VDragAndDropWrapper.java
+++ b/client/src/main/java/com/vaadin/client/ui/VDragAndDropWrapper.java
@@ -248,7 +248,7 @@ public class VDragAndDropWrapper extends VCustomComponent
             @Override
             public void execute() {
                 if (!uploading) {
-                    if (fileIds.size() > 0) {
+                    if (!fileIds.isEmpty()) {
 
                         uploading = true;
                         final Integer fileId = fileIds.remove(0);
diff --git a/client/src/main/java/com/vaadin/client/ui/VMenuBar.java b/client/src/main/java/com/vaadin/client/ui/VMenuBar.java
index 8f0026dc14..432f44fe05 100644
--- a/client/src/main/java/com/vaadin/client/ui/VMenuBar.java
+++ b/client/src/main/java/com/vaadin/client/ui/VMenuBar.java
@@ -1116,7 +1116,7 @@ public class VMenuBar extends SimpleFocusablePanel
         // Only collapse if there is more than one item in the root menu and the
         // menu has an explicit size
         if ((getItems().size() > 1 || (collapsedRootItems != null
-                && collapsedRootItems.getItems().size() > 0))
+                && !collapsedRootItems.getItems().isEmpty()))
                 && getElement().getStyle().getProperty("width") != null
                 && moreItem != null) {
 
@@ -1144,7 +1144,7 @@ public class VMenuBar extends SimpleFocusablePanel
                 }
                 int widthReduced = 0;
 
-                while (widthReduced < widthNeeded && getItems().size() > 0) {
+                while (widthReduced < widthNeeded && !getItems().isEmpty()) {
                     // Move last root menu item to collapsed menu
                     CustomMenuItem collapse = getItems()
                             .get(getItems().size() - 1);
@@ -1152,21 +1152,21 @@ public class VMenuBar extends SimpleFocusablePanel
                     removeItem(collapse);
                     collapsedRootItems.addItem(collapse, 0);
                 }
-            } else if (collapsedRootItems.getItems().size() > 0) {
+            } else if (!collapsedRootItems.getItems().isEmpty()) {
                 // Space available for items: expand first items from collapsed
                 // menu
                 int widthAvailable = diff + moreItemWidth;
                 int widthGrowth = 0;
 
                 while (widthAvailable > widthGrowth
-                        && collapsedRootItems.getItems().size() > 0) {
+                        && !collapsedRootItems.getItems().isEmpty()) {
                     // Move first item from collapsed menu to the root menu
                     CustomMenuItem expand = collapsedRootItems.getItems()
                             .get(0);
                     collapsedRootItems.removeItem(expand);
                     addItem(expand);
                     widthGrowth += expand.getOffsetWidth();
-                    if (collapsedRootItems.getItems().size() > 0) {
+                    if (!collapsedRootItems.getItems().isEmpty()) {
                         widthAvailable -= moreItemWidth;
                     }
                     if (widthGrowth > widthAvailable) {
@@ -1177,7 +1177,7 @@ public class VMenuBar extends SimpleFocusablePanel
                     }
                 }
             }
-            if (collapsedRootItems.getItems().size() > 0) {
+            if (!collapsedRootItems.getItems().isEmpty()) {
                 addItem(moreItem);
             }
         }
diff --git a/client/src/main/java/com/vaadin/client/ui/VWindow.java b/client/src/main/java/com/vaadin/client/ui/VWindow.java
index c39da6d168..df2c4b17f3 100644
--- a/client/src/main/java/com/vaadin/client/ui/VWindow.java
+++ b/client/src/main/java/com/vaadin/client/ui/VWindow.java
@@ -327,7 +327,7 @@ public class VWindow extends VOverlay implements ShortcutActionHandlerOwner,
     }
 
     private static VWindow getTopmostWindow() {
-        if (windowOrder.size() > 0) {
+        if (!windowOrder.isEmpty()) {
             return windowOrder.get(windowOrder.size() - 1);
         }
         return null;
diff --git a/client/src/main/java/com/vaadin/client/ui/menubar/MenuBar.java b/client/src/main/java/com/vaadin/client/ui/menubar/MenuBar.java
index 099cf15489..fae876165b 100644
--- a/client/src/main/java/com/vaadin/client/ui/menubar/MenuBar.java
+++ b/client/src/main/java/com/vaadin/client/ui/menubar/MenuBar.java
@@ -331,7 +331,7 @@ public class MenuBar extends Widget implements PopupListener {
      * @return the first item from the menu or null if no items.
      */
     public MenuItem getFirstItem() {
-        return items != null && items.size() > 0 ? items.get(0) : null;
+        return items != null && !items.isEmpty() ? items.get(0) : null;
     }
 
     /**
@@ -341,7 +341,7 @@ public class MenuBar extends Widget implements PopupListener {
      * @return the last item from the menu or null if no items.
      */
     public MenuItem getLastItem() {
-        return items != null && items.size() > 0 ? items.get(items.size() - 1)
+        return items != null && !items.isEmpty() ? items.get(items.size() - 1)
                 : null;
     }
 
@@ -627,7 +627,7 @@ public class MenuBar extends Widget implements PopupListener {
      */
     private void onShow() {
         // Select the first item when a menu is shown.
-        if (items.size() > 0) {
+        if (!items.isEmpty()) {
             selectItem(items.get(0));
         }
     }
diff --git a/client/src/main/java/com/vaadin/client/widget/grid/datasources/ListSorter.java b/client/src/main/java/com/vaadin/client/widget/grid/datasources/ListSorter.java
index 14cb2e6523..07fc05622b 100644
--- a/client/src/main/java/com/vaadin/client/widget/grid/datasources/ListSorter.java
+++ b/client/src/main/java/com/vaadin/client/widget/grid/datasources/ListSorter.java
@@ -159,11 +159,12 @@ public class ListSorter<T> {
 
                     if (result != 0) {
                         return o.getDirection() == SortDirection.ASCENDING
-                                ? result : -result;
+                                ? result
+                                : -result;
                     }
                 }
 
-                if (order.size() > 0) {
+                if (!order.isEmpty()) {
                     return order.get(0)
                             .getDirection() == SortDirection.ASCENDING
                                     ? a.hashCode() - b.hashCode()
diff --git a/client/src/main/java/com/vaadin/client/widgets/Escalator.java b/client/src/main/java/com/vaadin/client/widgets/Escalator.java
index 6adc0cbef9..61887dd980 100644
--- a/client/src/main/java/com/vaadin/client/widgets/Escalator.java
+++ b/client/src/main/java/com/vaadin/client/widgets/Escalator.java
@@ -425,7 +425,7 @@ public class Escalator extends Widget
                         velocity = delta / ellapsed;
                         // if last speed was so low, reset speeds and start
                         // storing again
-                        if (speeds.size() > 0 && !validSpeed(speeds.get(0))) {
+                        if (!speeds.isEmpty() && !validSpeed(speeds.get(0))) {
                             speeds.clear();
                             run = true;
                         }