Use String.isEmpty() (#10045)

15 files changed, 16 insertions, 16 deletions

diff --git a/server/src/main/java/com/vaadin/server/AbstractErrorMessage.java b/server/src/main/java/com/vaadin/server/AbstractErrorMessage.java
index 6ffbf6063e..cad1dc425d 100644
--- a/server/src/main/java/com/vaadin/server/AbstractErrorMessage.java
+++ b/server/src/main/java/com/vaadin/server/AbstractErrorMessage.java
@@ -129,7 +129,7 @@ public abstract class AbstractErrorMessage implements ErrorMessage {
                     sb.append("</div>\n");
                 }
             }
-            if (sb.length() > 0) {
+            if (sb.length() != 0) {
                 result = sb.toString();
             }
         }
diff --git a/server/src/main/java/com/vaadin/server/BootstrapHandler.java b/server/src/main/java/com/vaadin/server/BootstrapHandler.java
index 1cba25fbf6..6b43dc3a64 100644
--- a/server/src/main/java/com/vaadin/server/BootstrapHandler.java
+++ b/server/src/main/java/com/vaadin/server/BootstrapHandler.java
@@ -659,7 +659,7 @@ public abstract class BootstrapHandler extends SynchronizedRequestHandler {
         mainDiv.addClass(context.getThemeName());
         mainDiv.addClass(context.getUIClass().getSimpleName()
                 .toLowerCase(Locale.ENGLISH));
-        if (style != null && style.length() != 0) {
+        if (style != null && !style.isEmpty()) {
             mainDiv.attr("style", style);
         }
         mainDiv.appendElement("div").addClass("v-app-loading");
diff --git a/server/src/main/java/com/vaadin/server/LegacyApplicationUIProvider.java b/server/src/main/java/com/vaadin/server/LegacyApplicationUIProvider.java
index 4ad7097e3b..1128bc85fd 100644
--- a/server/src/main/java/com/vaadin/server/LegacyApplicationUIProvider.java
+++ b/server/src/main/java/com/vaadin/server/LegacyApplicationUIProvider.java
@@ -78,7 +78,7 @@ public abstract class LegacyApplicationUIProvider extends UIProvider {
         VaadinRequest request = event.getRequest();
         String pathInfo = request.getPathInfo();
         String name = null;
-        if (pathInfo != null && pathInfo.length() > 0) {
+        if (pathInfo != null && !pathInfo.isEmpty()) {
             Matcher matcher = WINDOW_NAME_PATTERN.matcher(pathInfo);
             if (matcher.matches()) {
                 // Skip the initial slash
diff --git a/server/src/main/java/com/vaadin/server/Page.java b/server/src/main/java/com/vaadin/server/Page.java
index 385aa0bf9a..4c880c2a6b 100644
--- a/server/src/main/java/com/vaadin/server/Page.java
+++ b/server/src/main/java/com/vaadin/server/Page.java
@@ -203,7 +203,7 @@ public class Page implements Serializable {
         private void paintContent(PaintTarget target) throws PaintException {
             target.startTag("open");
             target.addAttribute("src", resource);
-            if (name != null && name.length() > 0) {
+            if (name != null && !name.isEmpty()) {
                 target.addAttribute("name", name);
             }
             if (!tryToOpenAsPopup) {
diff --git a/server/src/main/java/com/vaadin/server/SizeWithUnit.java b/server/src/main/java/com/vaadin/server/SizeWithUnit.java
index b1b34e1fef..d5894f4e12 100644
--- a/server/src/main/java/com/vaadin/server/SizeWithUnit.java
+++ b/server/src/main/java/com/vaadin/server/SizeWithUnit.java
@@ -98,7 +98,7 @@ public class SizeWithUnit implements Serializable {
                 unit = Unit.PIXELS;
             } else {
                 String symbol = matcher.group(2);
-                if ((symbol != null && symbol.length() > 0)
+                if ((symbol != null && !symbol.isEmpty())
                         || defaultUnit == null) {
                     unit = Unit.getUnitFromSymbol(symbol);
                 } else {
diff --git a/server/src/main/java/com/vaadin/server/ThemeResource.java b/server/src/main/java/com/vaadin/server/ThemeResource.java
index 8fc0a76bad..4410aa4cb7 100644
--- a/server/src/main/java/com/vaadin/server/ThemeResource.java
+++ b/server/src/main/java/com/vaadin/server/ThemeResource.java
@@ -45,7 +45,7 @@ public class ThemeResource implements Resource {
         if (resourceId == null) {
             throw new NullPointerException("Resource ID must not be null");
         }
-        if (resourceId.length() == 0) {
+        if (resourceId.isEmpty()) {
             throw new IllegalArgumentException("Resource ID can not be empty");
         }
         if (resourceId.charAt(0) == '/') {
diff --git a/server/src/main/java/com/vaadin/server/VaadinServlet.java b/server/src/main/java/com/vaadin/server/VaadinServlet.java
index d2498dddfc..638eeb047f 100644
--- a/server/src/main/java/com/vaadin/server/VaadinServlet.java
+++ b/server/src/main/java/com/vaadin/server/VaadinServlet.java
@@ -1412,7 +1412,7 @@ public class VaadinServlet extends HttpServlet implements Constants {
             servletPath = request.getContextPath() + request.getServletPath();
         }
 
-        if (servletPath.length() == 0
+        if (servletPath.isEmpty()
                 || servletPath.charAt(servletPath.length() - 1) != '/') {
             servletPath += "/";
         }
diff --git a/server/src/main/java/com/vaadin/ui/AbstractOrderedLayout.java b/server/src/main/java/com/vaadin/ui/AbstractOrderedLayout.java
index a90f8e8d8a..43f78f7c1b 100644
--- a/server/src/main/java/com/vaadin/ui/AbstractOrderedLayout.java
+++ b/server/src/main/java/com/vaadin/ui/AbstractOrderedLayout.java
@@ -476,7 +476,7 @@ public abstract class AbstractOrderedLayout extends AbstractLayout
             // handle expand ratio
             if (attr.hasKey(":expand")) {
                 String value = attr.get(":expand");
-                if (value.length() > 0) {
+                if (!value.isEmpty()) {
                     try {
                         float ratio = Float.valueOf(value);
                         setExpandRatio(newChild, ratio);
diff --git a/server/src/main/java/com/vaadin/ui/ComboBox.java b/server/src/main/java/com/vaadin/ui/ComboBox.java
index af100e03f1..0d7e7fc619 100644
--- a/server/src/main/java/com/vaadin/ui/ComboBox.java
+++ b/server/src/main/java/com/vaadin/ui/ComboBox.java
@@ -155,7 +155,7 @@ public class ComboBox<T> extends AbstractSingleSelect<T>
         public void createNewItem(String itemValue) {
             // New option entered
             if (getNewItemHandler() != null && itemValue != null
-                    && itemValue.length() > 0) {
+                    && !itemValue.isEmpty()) {
                 getNewItemHandler().accept(itemValue);
             }
         }
diff --git a/server/src/main/java/com/vaadin/ui/CustomLayout.java b/server/src/main/java/com/vaadin/ui/CustomLayout.java
index 0293b0a648..d44a02f52e 100644
--- a/server/src/main/java/com/vaadin/ui/CustomLayout.java
+++ b/server/src/main/java/com/vaadin/ui/CustomLayout.java
@@ -307,7 +307,7 @@ public class CustomLayout extends AbstractLayout implements LegacyComponent {
         // Workaround to make the CommunicationManager read the template file
         // and send it to the client
         String templateName = getState(false).templateName;
-        if (templateName != null && templateName.length() != 0) {
+        if (templateName != null && !templateName.isEmpty()) {
             Set<Object> usedResources = ((JsonPaintTarget) target)
                     .getUsedResources();
             String resourceName = "layouts/" + templateName + ".html";
diff --git a/server/src/main/java/com/vaadin/ui/MenuBar.java b/server/src/main/java/com/vaadin/ui/MenuBar.java
index 9cf60faddc..39d66bd0b0 100644
--- a/server/src/main/java/com/vaadin/ui/MenuBar.java
+++ b/server/src/main/java/com/vaadin/ui/MenuBar.java
@@ -139,7 +139,7 @@ public class MenuBar extends AbstractComponent
             }
 
             String description = item.getDescription();
-            if (description != null && description.length() > 0) {
+            if (description != null && !description.isEmpty()) {
                 target.addAttribute(MenuBarConstants.ATTRIBUTE_ITEM_DESCRIPTION,
                         description);
             }
diff --git a/server/src/main/java/com/vaadin/ui/declarative/DesignAttributeHandler.java b/server/src/main/java/com/vaadin/ui/declarative/DesignAttributeHandler.java
index dde1624352..0fbfe9c6b5 100644
--- a/server/src/main/java/com/vaadin/ui/declarative/DesignAttributeHandler.java
+++ b/server/src/main/java/com/vaadin/ui/declarative/DesignAttributeHandler.java
@@ -327,7 +327,7 @@ public class DesignAttributeHandler implements Serializable {
         String[] words = propertyName.split("(?<!^)(?=[A-Z])");
         StringBuilder builder = new StringBuilder();
         for (int i = 0; i < words.length; i++) {
-            if (builder.length() > 0) {
+            if (builder.length() != 0) {
                 builder.append("-");
             }
             builder.append(words[i].toLowerCase());
diff --git a/server/src/main/java/com/vaadin/ui/declarative/DesignContext.java b/server/src/main/java/com/vaadin/ui/declarative/DesignContext.java
index e3237ada53..042fa77826 100644
--- a/server/src/main/java/com/vaadin/ui/declarative/DesignContext.java
+++ b/server/src/main/java/com/vaadin/ui/declarative/DesignContext.java
@@ -530,7 +530,7 @@ public class DesignContext implements Serializable {
         // global id: only update the mapping, the id has already been set for
         // the component
         String id = component.getId();
-        if (id != null && id.length() > 0) {
+        if (id != null && !id.isEmpty()) {
             boolean mappingExists = mapId(id, component);
             if (mappingExists) {
                 throw new DesignException(
diff --git a/server/src/main/java/com/vaadin/ui/declarative/FieldBinder.java b/server/src/main/java/com/vaadin/ui/declarative/FieldBinder.java
index f860e30e7c..dfd7033430 100644
--- a/server/src/main/java/com/vaadin/ui/declarative/FieldBinder.java
+++ b/server/src/main/java/com/vaadin/ui/declarative/FieldBinder.java
@@ -176,7 +176,7 @@ public class FieldBinder implements Serializable {
         try {
             // create and validate field name
             String fieldName = asFieldName(identifier);
-            if (fieldName.length() == 0) {
+            if (fieldName.isEmpty()) {
                 return false;
             }
             // validate that the field can be found
@@ -231,7 +231,7 @@ public class FieldBinder implements Serializable {
             }
         }
         // lowercase first letter
-        if (result.length() > 0 && Character.isLetter(result.charAt(0))) {
+        if (result.length() != 0 && Character.isLetter(result.charAt(0))) {
             result.setCharAt(0, Character.toLowerCase(result.charAt(0)));
         }
         return result.toString();
diff --git a/server/src/main/java/com/vaadin/ui/declarative/converters/DesignShortcutActionConverter.java b/server/src/main/java/com/vaadin/ui/declarative/converters/DesignShortcutActionConverter.java
index b4f38928a9..aade7e80b7 100644
--- a/server/src/main/java/com/vaadin/ui/declarative/converters/DesignShortcutActionConverter.java
+++ b/server/src/main/java/com/vaadin/ui/declarative/converters/DesignShortcutActionConverter.java
@@ -123,7 +123,7 @@ public class DesignShortcutActionConverter
     @Override
     public Result<ShortcutAction> convertToModel(String value,
             ValueContext context) {
-        if (value.length() == 0) {
+        if (value.isEmpty()) {
             return Result.ok(null);
         }