Use String.isEmpty() (#10045)

18 files changed, 34 insertions, 34 deletions

diff --git a/client/src/main/java/com/vaadin/client/JavaScriptConnectorHelper.java b/client/src/main/java/com/vaadin/client/JavaScriptConnectorHelper.java
index f0a6e7057a..05449f1126 100644
--- a/client/src/main/java/com/vaadin/client/JavaScriptConnectorHelper.java
+++ b/client/src/main/java/com/vaadin/client/JavaScriptConnectorHelper.java
@@ -331,7 +331,7 @@ public class JavaScriptConnectorHelper {
     }
 
     private ServerConnector getConnector(String connectorId) {
-        if (connectorId == null || connectorId.length() == 0) {
+        if (connectorId == null || connectorId.isEmpty()) {
             return connector;
         }
 
@@ -364,7 +364,7 @@ public class JavaScriptConnectorHelper {
             // TODO Resolve conflicts using argument count and types
             String interfaceList = "";
             for (String iface : interfaces) {
-                if (interfaceList.length() != 0) {
+                if (!interfaceList.isEmpty()) {
                     interfaceList += ", ";
                 }
                 interfaceList += getJsInterfaceName(iface);
diff --git a/client/src/main/java/com/vaadin/client/ResourceLoader.java b/client/src/main/java/com/vaadin/client/ResourceLoader.java
index 53967a74f7..12922dca00 100644
--- a/client/src/main/java/com/vaadin/client/ResourceLoader.java
+++ b/client/src/main/java/com/vaadin/client/ResourceLoader.java
@@ -141,7 +141,7 @@ public class ResourceLoader {
         for (int i = 0; i < scripts.getLength(); i++) {
             ScriptElement element = ScriptElement.as(scripts.getItem(i));
             String src = element.getSrc();
-            if (src != null && src.length() != 0) {
+            if (src != null && !src.isEmpty()) {
                 loadedResources.add(src);
             }
         }
@@ -152,11 +152,11 @@ public class ResourceLoader {
             String rel = linkElement.getRel();
             String href = linkElement.getHref();
             if ("stylesheet".equalsIgnoreCase(rel) && href != null
-                    && href.length() != 0) {
+                    && !href.isEmpty()) {
                 loadedResources.add(href);
             }
             if ("import".equalsIgnoreCase(rel) && href != null
-                    && href.length() != 0) {
+                    && !href.isEmpty()) {
                 loadedResources.add(href);
             }
         }
diff --git a/client/src/main/java/com/vaadin/client/VErrorMessage.java b/client/src/main/java/com/vaadin/client/VErrorMessage.java
index b87704f3e0..0baa1baff1 100644
--- a/client/src/main/java/com/vaadin/client/VErrorMessage.java
+++ b/client/src/main/java/com/vaadin/client/VErrorMessage.java
@@ -49,7 +49,7 @@ public class VErrorMessage extends FlowPanel {
 
     public void updateMessage(String htmlErrorMessage) {
         clear();
-        if (htmlErrorMessage == null || htmlErrorMessage.length() == 0) {
+        if (htmlErrorMessage == null || htmlErrorMessage.isEmpty()) {
             add(new HTML(" "));
         } else {
             // pre-formatted on the server as div per child
diff --git a/client/src/main/java/com/vaadin/client/WidgetUtil.java b/client/src/main/java/com/vaadin/client/WidgetUtil.java
index 3390881b72..d24a1d53a5 100644
--- a/client/src/main/java/com/vaadin/client/WidgetUtil.java
+++ b/client/src/main/java/com/vaadin/client/WidgetUtil.java
@@ -934,7 +934,7 @@ public class WidgetUtil {
     public static void forceWebkitRedraw(Element element) {
         Style style = element.getStyle();
         String s = style.getProperty("webkitTransform");
-        if (s == null || s.length() == 0) {
+        if (s == null || s.isEmpty()) {
             style.setProperty("webkitTransform", "scale(1)");
         } else {
             style.setProperty("webkitTransform", "");
diff --git a/client/src/main/java/com/vaadin/client/componentlocator/SelectorPredicate.java b/client/src/main/java/com/vaadin/client/componentlocator/SelectorPredicate.java
index f01c693c4c..ddab95d2c9 100644
--- a/client/src/main/java/com/vaadin/client/componentlocator/SelectorPredicate.java
+++ b/client/src/main/java/com/vaadin/client/componentlocator/SelectorPredicate.java
@@ -42,9 +42,9 @@ public class SelectorPredicate {
     }
 
     /**
-     * Generate a list of predicates from a single predicate string
+     * Generates a list of predicates from a single predicate string.
      *
-     * @param str
+     * @param path
      *            a comma separated string of predicates
      * @return a List of Predicate objects
      */
@@ -52,7 +52,7 @@ public class SelectorPredicate {
         List<SelectorPredicate> predicates = new ArrayList<>();
 
         String predicateStr = extractPredicateString(path);
-        if (null == predicateStr || predicateStr.length() == 0) {
+        if (null == predicateStr || predicateStr.isEmpty()) {
             return predicates;
         }
 
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 c7abe8c15f..77e1ee0a09 100644
--- a/client/src/main/java/com/vaadin/client/componentlocator/VaadinFinderLocatorStrategy.java
+++ b/client/src/main/java/com/vaadin/client/componentlocator/VaadinFinderLocatorStrategy.java
@@ -424,7 +424,7 @@ public class VaadinFinderLocatorStrategy implements LocatorStrategy {
             ComponentConnector root, Element actualRoot) {
         String[] pathComponents = path.split(SUBPART_SEPARATOR);
         List<ComponentConnector> connectors;
-        if (pathComponents[0].length() > 0) {
+        if (!pathComponents[0].isEmpty()) {
             connectors = findConnectorsByPath(pathComponents[0],
                     Arrays.asList(root));
         } else {
diff --git a/client/src/main/java/com/vaadin/client/connectors/grid/GridDropTargetConnector.java b/client/src/main/java/com/vaadin/client/connectors/grid/GridDropTargetConnector.java
index ae24ed850f..44a60b9fd5 100644
--- a/client/src/main/java/com/vaadin/client/connectors/grid/GridDropTargetConnector.java
+++ b/client/src/main/java/com/vaadin/client/connectors/grid/GridDropTargetConnector.java
@@ -273,7 +273,7 @@ public class GridDropTargetConnector extends DropTargetExtensionConnector {
                 if ("thead".equalsIgnoreCase(parentTagName)) {
                     // for empty grid or ON_TOP mode, drop as last row,
                     // otherwise as above first visible row
-                    if (visibleRowRange.length() == 0
+                    if (visibleRowRange.isEmpty()
                             || getState().dropMode == DropMode.ON_TOP) {
                         return tableWrapper;
                     } else {
@@ -283,7 +283,7 @@ public class GridDropTargetConnector extends DropTargetExtensionConnector {
                 } else if ("tfoot".equalsIgnoreCase(parentTagName)) {
                     // for empty grid or ON_TOP mode, drop as last row,
                     // otherwise as below last visible row
-                    if (visibleRowRange.length() == 0
+                    if (visibleRowRange.isEmpty()
                             || getState().dropMode == DropMode.ON_TOP) {
                         return tableWrapper;
                     } else {
@@ -299,7 +299,7 @@ public class GridDropTargetConnector extends DropTargetExtensionConnector {
         // the drag is on top of the tablewrapper
         // if no rows in grid, or if the drop mode is ON_TOP, then there is no
         // target row for the drop
-        if (visibleRowRange.length() == 0
+        if (visibleRowRange.isEmpty()
                 || getState().dropMode == DropMode.ON_TOP) {
             return tableWrapper;
         } else { // if dragged under the last row to empty space, drop target
diff --git a/client/src/main/java/com/vaadin/client/ui/VAccordion.java b/client/src/main/java/com/vaadin/client/ui/VAccordion.java
index 73f48639f3..16c16935d0 100644
--- a/client/src/main/java/com/vaadin/client/ui/VAccordion.java
+++ b/client/src/main/java/com/vaadin/client/ui/VAccordion.java
@@ -376,13 +376,13 @@ public class VAccordion extends VTabsheetBase {
          * Updates a tabs stylename from the child UIDL
          *
          * @param uidl
-         *            The child uidl of the tab
+         *            The child UIDL of the tab
          */
         private void updateTabStyleName(String newStyleName) {
-            if (newStyleName != null && newStyleName.length() != 0) {
+            if (newStyleName != null && !newStyleName.isEmpty()) {
                 if (!newStyleName.equals(styleName)) {
                     // If we have a new style name
-                    if (styleName != null && styleName.length() != 0) {
+                    if (styleName != null && !styleName.isEmpty()) {
                         // Remove old style name if present
                         removeStyleDependentName(styleName);
                     }
diff --git a/client/src/main/java/com/vaadin/client/ui/VCheckBoxGroup.java b/client/src/main/java/com/vaadin/client/ui/VCheckBoxGroup.java
index 427c4011a5..a957690526 100644
--- a/client/src/main/java/com/vaadin/client/ui/VCheckBoxGroup.java
+++ b/client/src/main/java/com/vaadin/client/ui/VCheckBoxGroup.java
@@ -124,7 +124,7 @@ public class VCheckBoxGroup extends FocusableFlowPanelComposite
         }
 
         String iconUrl = item.getString(ListingJsonConstants.JSONKEY_ITEM_ICON);
-        if (iconUrl != null && iconUrl.length() != 0) {
+        if (iconUrl != null && !iconUrl.isEmpty()) {
             Icon icon = client.getIcon(iconUrl);
             itemHtml = icon.getElement().getString() + itemHtml;
         }
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 ebb993702c..c872026ac7 100644
--- a/client/src/main/java/com/vaadin/client/ui/VComboBox.java
+++ b/client/src/main/java/com/vaadin/client/ui/VComboBox.java
@@ -1287,7 +1287,7 @@ public class VComboBox extends Composite implements Field, KeyDownHandler,
             String height = getElement().getStyle().getHeight();
             String preferredHeight = getPreferredHeight(pageLength);
 
-            return !(height == null || height.length() == 0
+            return !(height == null || height.isEmpty()
                     || height.equals(preferredHeight));
         }
 
@@ -2038,7 +2038,7 @@ public class VComboBox extends Composite implements Field, KeyDownHandler,
         if (selectedItemIcon != null) {
             panel.remove(selectedItemIcon);
         }
-        if (iconUri == null || iconUri.length() == 0) {
+        if (iconUri == null || iconUri.isEmpty()) {
             if (selectedItemIcon != null) {
                 selectedItemIcon = null;
                 afterSelectedItemIconChange();
@@ -2422,7 +2422,7 @@ public class VComboBox extends Composite implements Field, KeyDownHandler,
         for (ComboBoxSuggestion suggestion : currentSuggestions) {
             // Collect captions so we can calculate minimum width for
             // textarea
-            if (captions.length() > 0) {
+            if (!captions.isEmpty()) {
                 captions += "|";
             }
             captions += WidgetUtil
@@ -2658,7 +2658,7 @@ public class VComboBox extends Composite implements Field, KeyDownHandler,
     @Override
     public void setWidth(String width) {
         super.setWidth(width);
-        if (width.length() != 0) {
+        if (!width.isEmpty()) {
             tb.setWidth("100%");
         }
     }
diff --git a/client/src/main/java/com/vaadin/client/ui/VLink.java b/client/src/main/java/com/vaadin/client/ui/VLink.java
index ede020e572..84aac0f17e 100644
--- a/client/src/main/java/com/vaadin/client/ui/VLink.java
+++ b/client/src/main/java/com/vaadin/client/ui/VLink.java
@@ -98,15 +98,15 @@ public class VLink extends HTML implements ClickHandler, HasEnabled {
             }
 
             if (targetWidth > 0) {
-                features += (features.length() > 0 ? "," : "") + "width="
+                features += (features.isEmpty() ? "" : ",") + "width="
                         + targetWidth;
             }
             if (targetHeight > 0) {
-                features += (features.length() > 0 ? "," : "") + "height="
+                features += (features.isEmpty() ? "" : ",") + "height="
                         + targetHeight;
             }
 
-            if (features.length() > 0) {
+            if (!features.isEmpty()) {
                 // if 'special features' are set, use window.open(), unless
                 // a modifier key is held (ctrl to open in new tab etc)
                 Event e = DOM.eventGetCurrentEvent();
diff --git a/client/src/main/java/com/vaadin/client/ui/VNotification.java b/client/src/main/java/com/vaadin/client/ui/VNotification.java
index e5358a3db7..0eaee0102c 100644
--- a/client/src/main/java/com/vaadin/client/ui/VNotification.java
+++ b/client/src/main/java/com/vaadin/client/ui/VNotification.java
@@ -247,7 +247,7 @@ public class VNotification extends VOverlay {
             removeStyleDependentName(temporaryStyle);
             temporaryStyle = null;
         }
-        if (style != null && style.length() > 0) {
+        if (style != null && !style.isEmpty()) {
             temporaryStyle = style;
             addStyleName(style);
             addStyleDependentName(style);
@@ -635,7 +635,7 @@ public class VNotification extends VOverlay {
             html.append("</p>");
         }
 
-        if (html.length() > 0) {
+        if (html.length() != 0) {
 
             // Add error description
             if (details != null) {
diff --git a/client/src/main/java/com/vaadin/client/ui/VRadioButtonGroup.java b/client/src/main/java/com/vaadin/client/ui/VRadioButtonGroup.java
index 15b0d6f043..4f0bed52ed 100644
--- a/client/src/main/java/com/vaadin/client/ui/VRadioButtonGroup.java
+++ b/client/src/main/java/com/vaadin/client/ui/VRadioButtonGroup.java
@@ -143,7 +143,7 @@ public class VRadioButtonGroup extends FocusableFlowPanelComposite
         }
 
         String iconUrl = item.getString(ListingJsonConstants.JSONKEY_ITEM_ICON);
-        if (iconUrl != null && iconUrl.length() != 0) {
+        if (iconUrl != null && !iconUrl.isEmpty()) {
             Icon icon = client.getIcon(iconUrl);
             itemHtml = icon.getElement().getString() + itemHtml;
         }
diff --git a/client/src/main/java/com/vaadin/client/ui/VUpload.java b/client/src/main/java/com/vaadin/client/ui/VUpload.java
index d25508d29a..dd4c295492 100644
--- a/client/src/main/java/com/vaadin/client/ui/VUpload.java
+++ b/client/src/main/java/com/vaadin/client/ui/VUpload.java
@@ -332,7 +332,7 @@ public class VUpload extends SimplePanel {
             VConsole.log("Submit cancelled (disabled or already submitted)");
             return;
         }
-        if (fu.getFilename().length() == 0) {
+        if (fu.getFilename().isEmpty()) {
             VConsole.log("Submitting empty selection (no file)");
         }
         // flush possibly pending variable changes, so they will be handled
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 c6d817587b..9e4aad0d2c 100644
--- a/client/src/main/java/com/vaadin/client/ui/VWindow.java
+++ b/client/src/main/java/com/vaadin/client/ui/VWindow.java
@@ -1204,7 +1204,7 @@ public class VWindow extends VOverlay implements ShortcutActionHandlerOwner,
         // Override PopupPanel which sets the width to the contents
         getElement().getStyle().setProperty("width", width);
         // Update v-has-width in case undefined window is resized
-        setStyleName("v-has-width", width != null && width.length() > 0);
+        setStyleName("v-has-width", width != null && !width.isEmpty());
     }
 
     @Override
@@ -1212,7 +1212,7 @@ public class VWindow extends VOverlay implements ShortcutActionHandlerOwner,
         // Override PopupPanel which sets the height to the contents
         getElement().getStyle().setProperty("height", height);
         // Update v-has-height in case undefined window is resized
-        setStyleName("v-has-height", height != null && height.length() > 0);
+        setStyleName("v-has-height", height != null && !height.isEmpty());
     }
 
     private void onDragEvent(Event event) {
diff --git a/client/src/main/java/com/vaadin/client/ui/layout/LayoutDependencyTree.java b/client/src/main/java/com/vaadin/client/ui/layout/LayoutDependencyTree.java
index 815509c44b..c837570c85 100644
--- a/client/src/main/java/com/vaadin/client/ui/layout/LayoutDependencyTree.java
+++ b/client/src/main/java/com/vaadin/client/ui/layout/LayoutDependencyTree.java
@@ -615,7 +615,7 @@ public class LayoutDependencyTree {
     }
 
     private static String getSizeDefinition(String size) {
-        if (size == null || size.length() == 0) {
+        if (size == null || size.isEmpty()) {
             return "undefined";
         } else if (size.endsWith("%")) {
             return "relative";
diff --git a/client/src/main/java/com/vaadin/client/ui/window/WindowConnector.java b/client/src/main/java/com/vaadin/client/ui/window/WindowConnector.java
index 4e28fb6349..dc8d30e517 100644
--- a/client/src/main/java/com/vaadin/client/ui/window/WindowConnector.java
+++ b/client/src/main/java/com/vaadin/client/ui/window/WindowConnector.java
@@ -252,7 +252,7 @@ public class WindowConnector extends AbstractSingleComponentContainerConnector
                 childStyle.setPosition(Position.ABSOLUTE);
 
                 Style wrapperStyle = contentElement.getStyle();
-                if (window.getElement().getStyle().getWidth().length() == 0
+                if (window.getElement().getStyle().getWidth().isEmpty()
                         && !content.isRelativeWidth()) {
                     /*
                      * Need to lock width to make undefined width work even with
diff --git a/client/src/test/java/com/vaadin/client/ApplicationConnectionURLGenerationTest.java b/client/src/test/java/com/vaadin/client/ApplicationConnectionURLGenerationTest.java
index 8a84208ea8..1473af44ae 100644
--- a/client/src/test/java/com/vaadin/client/ApplicationConnectionURLGenerationTest.java
+++ b/client/src/test/java/com/vaadin/client/ApplicationConnectionURLGenerationTest.java
@@ -56,7 +56,7 @@ public class ApplicationConnectionURLGenerationTest {
                     SharedUtil.addGetParameters(URIS[i], "a=b&c=d"));
 
             // Fragments
-            if (URIS_WITH_ABCD_PARAM_AND_FRAGMENT[i].length() > 0) {
+            if (!URIS_WITH_ABCD_PARAM_AND_FRAGMENT[i].isEmpty()) {
                 assertEquals(URIS_WITH_ABCD_PARAM_AND_FRAGMENT[i], SharedUtil
                         .addGetParameters(URIS[i] + "#fragment", "a=b&c=d"));