Replace iterators with enhanced for loops (#10018)

This change also includes some other minor cleanup.

client/src/main/java/com/vaadin/client/ui/VCustomLayout.java

@@ -339,9 +339,7 @@ public class VCustomLayout extends ComplexPanel {
 
     /** Get the location of an widget */
     public String getLocation(Widget w) {
-        for (final Iterator<String> i = locationToWidget.keySet().iterator(); i
-                .hasNext();) {
-            final String location = i.next();
+        for (final String location : locationToWidget.keySet()) {
             if (locationToWidget.get(location) == w) {
                 return location;
             }

client/src/main/java/com/vaadin/client/ui/VNotification.java

@@ -466,17 +466,14 @@ public class VNotification extends VOverlay {
     }
 
     public void removeEventListener(EventListener listener) {
-        if (listeners == null) {
-            return;
+        if (listeners != null) {
+            listeners.remove(listener);
         }
-        listeners.remove(listener);
     }
 
     private void fireEvent(HideEvent event) {
         if (listeners != null) {
-            for (Iterator<EventListener> it = listeners.iterator(); it
-                    .hasNext();) {
-                EventListener l = it.next();
+            for (EventListener l : listeners) {
                 l.notificationHidden(event);
             }
         }

client/src/main/java/com/vaadin/client/ui/tabsheet/TabsheetBaseConnector.java

@@ -96,9 +96,7 @@ public abstract class TabsheetBaseConnector
         }
 
         // Detach any old tab widget, should be max 1
-        for (Iterator<Widget> iterator = oldWidgets.iterator(); iterator
-                .hasNext();) {
-            Widget oldWidget = iterator.next();
+        for (Widget oldWidget : oldWidgets) {
             if (oldWidget.isAttached()) {
                 oldWidget.removeFromParent();
             }

compatibility-client/src/main/java/com/vaadin/v7/client/ui/VScrollTable.java

@@ -4031,9 +4031,8 @@ public class VScrollTable extends FlowPanel
                 for (i = 0; i < visibleColOrder.length; i++) {
                     cols[i] = visibleColOrder[i];
                 }
-                for (final Iterator<String> it = collapsedColumns.iterator(); it
-                        .hasNext();) {
-                    cols[i++] = it.next();
+                for (final String column : collapsedColumns) {
+                    cols[i++] = column;
                 }
             }
             List<Action> actions = new ArrayList<Action>(cols.length);
@@ -4401,11 +4400,11 @@ public class VScrollTable extends FlowPanel
                         .getOffsetWidth() + getHeaderPadding();
                 if (columnIndex < 0) {
                     columnIndex = 0;
-                    for (Iterator<Widget> it = tHead.iterator(); it
-                            .hasNext(); columnIndex++) {
-                        if (it.next() == this) {
+                    for (Widget widget : tHead) {
+                        if (widget == this) {
                             break;
                         }
+                        columnIndex++;
                     }
                 }
                 final int cw = scrollBody.getColWidth(columnIndex);
@@ -6441,14 +6440,10 @@ public class VScrollTable extends FlowPanel
                     // Hide rows which are not selected
                     Element dragImage = ev.getDragImage();
                     int i = 0;
-                    for (Iterator<Widget> iterator = scrollBody
-                            .iterator(); iterator.hasNext();) {
-                        VScrollTableRow next = (VScrollTableRow) iterator
-                                .next();
-
+                    for (Widget next : scrollBody) {
                         Element child = (Element) dragImage.getChild(i++);
 
-                        if (!rowKeyIsSelected(next.rowKey)) {
+                        if (!rowKeyIsSelected(((VScrollTableRow) next).rowKey)) {
                             child.getStyle().setVisibility(Visibility.HIDDEN);
                         }
                     }

compatibility-server/src/test/java/com/vaadin/v7/tests/VaadinClasses.java

@@ -19,7 +19,7 @@ public class VaadinClasses {
 
     private static final Set<String> WHITE_LIST_FQNS = new HashSet<String>();
 
-    public static List<Class<? extends Field>> getFields() {
+    public static List<Class<? extends Field<?>>> getFields() {
         return getServerClasses(Field.class::isAssignableFrom)
                 .map(VaadinClasses::castFieldClass)
                 .collect(Collectors.toList());
@@ -50,8 +50,8 @@ public class VaadinClasses {
                 .collect(Collectors.toList());
     }
 
-    private static Class<? extends Field> castFieldClass(Class<?> clazz) {
-        return (Class<? extends Field>) clazz;
+    private static Class<? extends Field<?>> castFieldClass(Class<?> clazz) {
+        return (Class<? extends Field<?>>) clazz;
     }
 
     private static Class<? extends Component> castComponentClass(

server/src/main/java/com/vaadin/server/ComponentSizeValidator.java

@@ -92,9 +92,7 @@ public class ComponentSizeValidator implements Serializable {
             }
         } else if (isForm(component)) {
             HasComponents form = (HasComponents) component;
-            for (Iterator<Component> iterator = form.iterator(); iterator
-                    .hasNext();) {
-                Component child = iterator.next();
+            for (Component child : form) {
                 errors = validateComponentRelativeSizes(child, errors, parent);
             }
         }
@@ -129,7 +127,7 @@ public class ComponentSizeValidator implements Serializable {
         StringBuffer err = new StringBuffer();
         err.append("Vaadin DEBUG\n");
 
-        StringBuilder indent = new StringBuilder("");
+        StringBuilder indent = new StringBuilder();
         ComponentInfo ci;
         if (attributes != null) {
             while (attributes.size() > LAYERS_SHOWN) {

server/src/main/java/com/vaadin/server/JsonPaintTarget.java

@@ -224,7 +224,7 @@ public class JsonPaintTarget implements PaintTarget {
      */
     static StringBuilder escapeXML(StringBuilder xml) {
         if (xml == null || xml.length() <= 0) {
-            return new StringBuilder("");
+            return new StringBuilder();
         }
 
         final StringBuilder result = new StringBuilder(xml.length() * 2);

server/src/main/java/com/vaadin/ui/Upload.java

@@ -841,9 +841,7 @@ public class Upload extends AbstractComponent
         // this is implemented differently than other listeners to maintain
         // backwards compatibility
         if (progressListeners != null) {
-            for (Iterator<ProgressListener> it = progressListeners
-                    .iterator(); it.hasNext();) {
-                ProgressListener l = it.next();
+            for (ProgressListener l : progressListeners) {
                 l.updateProgress(totalBytes, contentLength);
             }
         }

uitest/src/main/java/com/vaadin/tests/ListenerOrder.java

@@ -89,10 +89,8 @@ public class ListenerOrder extends com.vaadin.server.LegacyApplication
         s1.addListener((ValueChangeListener) this);
 
         Item i = s1.getItem("second");
-        for (Iterator<?> it = i.getItemPropertyIds().iterator(); it
-                .hasNext();) {
-            Object o = it.next();
-            System.out.println("[" + o + "]");
+        for (Object id : i.getItemPropertyIds()) {
+            System.out.println("[" + id + "]");
         }
 
     }

uitest/src/main/java/com/vaadin/tests/Parameters.java

@@ -114,10 +114,9 @@ public class Parameters extends com.vaadin.server.LegacyApplication
 
         params.removeAllItems();
         Map<String, String[]> parameters = request.getParameterMap();
-        for (final Iterator<String> i = parameters.keySet().iterator(); i
-                .hasNext();) {
-            final String name = i.next();
-            final String[] values = parameters.get(name);
+        for (final Map.Entry<String, String[]> entry : parameters.entrySet()) {
+            final String name = entry.getKey();
+            final String[] values = entry.getValue();
             String v = "";
             for (int j = 0; j < values.length; j++) {
                 if (v.length() > 0) {

uitest/src/main/java/com/vaadin/tests/TestBench.java

@@ -20,9 +20,10 @@ import java.io.File;
 import java.net.URL;
 import java.util.ArrayList;
 import java.util.Enumeration;
-import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
+import java.util.Set;
 
 import com.vaadin.server.ExternalResource;
 import com.vaadin.server.LegacyApplication;
@@ -69,8 +70,7 @@ public class TestBench extends com.vaadin.server.LegacyApplication
 
     VerticalLayout bodyLayout = new VerticalLayout();
 
-    // TODO this could probably be a simple Set
-    HashMap<Class<?>, String> itemCaptions = new HashMap<>();
+    Set<Class<?>> itemCaptions = new HashSet<>();
 
     @Override
     public void init() {
@@ -81,23 +81,21 @@ public class TestBench extends com.vaadin.server.LegacyApplication
             try {
                 final List<Class<?>> testableClasses = getTestableClassesForPackage(
                         testablePackages[p]);
-                for (final Iterator<Class<?>> it = testableClasses
-                        .iterator(); it.hasNext();) {
-                    final Class<?> t = it.next();
+                for (final Class<?> t : testableClasses) {
                     // ignore TestBench itself
                     if (t.equals(TestBench.class)) {
                         continue;
                     }
                     try {
                         testables.addItem(t);
-                        itemCaptions.put(t, t.getName());
+                        itemCaptions.add(t);
                         testables.setParent(t, testablePackages[p]);
                         testables.setChildrenAllowed(t, false);
                         continue;
                     } catch (final Exception e) {
                         try {
                             testables.addItem(t);
-                            itemCaptions.put(t, t.getName());
+                            itemCaptions.add(t);
                             testables.setParent(t, testablePackages[p]);
                             testables.setChildrenAllowed(t, false);
                             continue;
@@ -113,18 +111,15 @@ public class TestBench extends com.vaadin.server.LegacyApplication
 
         menu = new Tree("Testables", testables);
 
-        for (final Iterator<Class<?>> i = itemCaptions.keySet().iterator(); i
-                .hasNext();) {
-            final Class<?> testable = i.next();
+        for (final Class<?> testable : itemCaptions) {
             // simplify captions
             final String name = testable.getName()
                     .substring(testable.getName().lastIndexOf('.') + 1);
             menu.setItemCaption(testable, name);
         }
         // expand all root items
-        for (final Iterator<?> i = menu.rootItemIds().iterator(); i
-                .hasNext();) {
-            menu.expandItemsRecursively(i.next());
+        for (final Object id : menu.rootItemIds()) {
+            menu.expandItemsRecursively(id);
         }
 
         menu.addListener(this);
@@ -302,8 +297,7 @@ public class TestBench extends com.vaadin.server.LegacyApplication
 
         final ArrayList<Class<?>> classes = new ArrayList<>();
         // For every directory identified capture all the .class files
-        for (final Iterator<File> it = directories.iterator(); it.hasNext();) {
-            final File directory = it.next();
+        for (final File directory : directories) {
             if (directory.exists()) {
                 // Get the list of the files contained in the package
                 final String[] files = directory.list();

uitest/src/main/java/com/vaadin/tests/TestForMultipleStyleNames.java

@@ -77,6 +77,7 @@ public class TestForMultipleStyleNames extends CustomComponent
 
     }
 
+    @SuppressWarnings("unchecked")
     @Override
     public void valueChange(ValueChangeEvent event) {
 
@@ -89,11 +90,9 @@ public class TestForMultipleStyleNames extends CustomComponent
             }
         }
 
-        final Collection<?> styles = (Collection<?>) s.getValue();
+        final Collection<String> styles = (Collection<String>) s.getValue();
 
-        for (final Iterator<?> iterator = styles.iterator(); iterator
-                .hasNext();) {
-            final String styleName = (String) iterator.next();
+        for (final String styleName : styles) {
             if (curStyles.contains(styleName)) {
                 // already added
                 curStyles.remove(styleName);
@@ -101,9 +100,7 @@ public class TestForMultipleStyleNames extends CustomComponent
                 l.addStyleName(styleName);
             }
         }
-        for (final Iterator<String> iterator2 = curStyles.iterator(); iterator2
-                .hasNext();) {
-            final String object = iterator2.next();
+        for (final String object : curStyles) {
             l.removeStyleName(object);
         }
     }

uitest/src/main/java/com/vaadin/tests/TestSizeableIncomponents.java

@@ -303,9 +303,7 @@ public class TestSizeableIncomponents extends LegacyApplication {
                 ((Label) c).setValue("Test label");
             }
 
-            for (Iterator<Configuration> i = configurations.iterator(); i
-                    .hasNext();) {
-                Configuration conf = i.next();
+            for (Configuration conf : configurations) {
                 conf.configure(c);
             }
             return c;

uitest/src/main/java/com/vaadin/tests/components/treetable/TreeTableTest.java

@@ -65,8 +65,7 @@ public class TreeTableTest extends Tables<TreeTable>
             Hierarchical c = getComponent().getContainerDataSource();
             int idx = 0;
 
-            for (Iterator<?> i = c.getItemIds().iterator(); i.hasNext();) {
-                Object id = i.next();
+            for (Object id : c.getItemIds()) {
                 if (id == itemId) {
                     if (idx % 2 == 1) {
                         return "bold";

uitest/src/main/java/com/vaadin/tests/dd/TreeDragStart.java

@@ -57,8 +57,8 @@ public class TreeDragStart extends TestBase {
         getLayout().addComponent(tree);
 
         // Expand all items
-        for (Iterator<?> it = tree.rootItemIds().iterator(); it.hasNext();) {
-            tree.expandItemsRecursively(it.next());
+        for (Object id : tree.rootItemIds()) {
+            tree.expandItemsRecursively(id);
         }
 
         // Set the tree in drag source mode

uitest/src/main/java/com/vaadin/tests/integration/JSR286Portlet.java

@@ -147,9 +147,9 @@ public class JSR286Portlet extends UI {
                 .getAttribute(PortletRequest.USER_INFO);
         if (uinfo != null) {
             String s = "";
-            for (Iterator<?> it = uinfo.keySet().iterator(); it.hasNext();) {
-                Object key = it.next();
-                Object val = uinfo.get(key);
+            for (Map.Entry<?, ?> entry : uinfo.entrySet()) {
+                Object key = entry.getKey();
+                Object val = entry.getValue();
                 s += key + ": " + val + "\n";
             }
             if (request.isUserInRole("administrator")) {

uitest/src/main/java/com/vaadin/tests/themes/valo/ValoThemeUI.java

@@ -146,15 +146,12 @@ public class ValoThemeUI extends UI {
 
             @Override
             public void afterViewChange(ViewChangeEvent event) {
-                for (Iterator<Component> it = menuItemsLayout.iterator(); it
-                        .hasNext();) {
-                    it.next().removeStyleName("selected");
+                for (Component c : menuItemsLayout) {
+                    c.removeStyleName("selected");
                 }
                 for (Entry<String, String> item : menuItems.entrySet()) {
                     if (event.getViewName().equals(item.getKey())) {
-                        for (Iterator<Component> it = menuItemsLayout
-                                .iterator(); it.hasNext();) {
-                            Component c = it.next();
+                        for (Component c : menuItemsLayout) {
                             if (c.getCaption() != null && c.getCaption()
                                     .startsWith(item.getValue())) {
                                 c.addStyleName("selected");

uitest/src/main/java/com/vaadin/v7/tests/components/tree/TreeHorizontalResize.java

@@ -35,8 +35,8 @@ public class TreeHorizontalResize extends TestBase {
         Tree tree = new Tree();
         tree.setContainerDataSource(getHardwareContainer());
         tree.setItemCaptionPropertyId(hw_PROPERTY_NAME);
-        for (Iterator<?> it = tree.rootItemIds().iterator(); it.hasNext();) {
-            tree.expandItemsRecursively(it.next());
+        for (Object id : tree.rootItemIds()) {
+            tree.expandItemsRecursively(id);
         }
         treeLayout.addComponent(tree);
     }

uitest/src/main/java/com/vaadin/v7/tests/components/tree/Trees.java

@@ -57,8 +57,7 @@ public class Trees extends AbstractSelectTestCase<Tree>
                     .getContainerDataSource();
             int idx = 0;
 
-            for (Iterator<?> i = c.getItemIds().iterator(); i.hasNext();) {
-                Object id = i.next();
+            for (Object id : c.getItemIds()) {
                 if (id == itemId) {
                     if (idx % 2 == 1) {
                         return "bold";