Simplify conditional logic.

client/src/main/java/com/vaadin/client/LayoutManager.java

@@ -144,21 +144,15 @@ public class LayoutManager {
             return true;
         } else if (elementResizeListeners.containsKey(e)) {
             return true;
-        } else if (getMeasuredSize(e, nullSize).hasDependents()) {
-            return true;
-        } else {
-            return false;
         }
+        return getMeasuredSize(e, nullSize).hasDependents();
     }
 
     private boolean needsMeasureForManagedLayout(ComponentConnector connector) {
         if (connector instanceof ManagedLayout) {
             return true;
-        } else if (connector.getParent() instanceof ManagedLayout) {
-            return true;
-        } else {
-            return false;
         }
+        return connector.getParent() instanceof ManagedLayout;
     }
 
     /**

client/src/main/java/com/vaadin/client/WidgetUtil.java

@@ -769,11 +769,7 @@ public class WidgetUtil {
             com.google.gwt.dom.client.Element pe) {
         String overflow = getComputedStyle(pe, "overflow");
         if (overflow != null) {
-            if (overflow.equals("auto") || overflow.equals("scroll")) {
-                return true;
-            } else {
-                return false;
-            }
+            return overflow.equals("auto") || overflow.equals("scroll");
         } else {
             return false;
         }

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

@@ -773,12 +773,8 @@ public abstract class AbstractComponentConnector extends AbstractConnector
         AbstractComponentState state = getState();
         if (state.description != null && !state.description.equals("")) {
             return true;
-        } else if (state.errorMessage != null
-                && !state.errorMessage.equals("")) {
-            return true;
-        } else {
-            return false;
         }
+        return state.errorMessage != null && !state.errorMessage.equals("");
     }
 
     /**

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

@@ -667,11 +667,7 @@ public class VDragAndDropWrapper extends VCustomComponent
                 drag.getCurrentGwtEvent(), 0.2);
         drag.getDropDetails().put("horizontalLocation",
                 horizontalDropLocation.toString());
-        if (oldHL != horizontalDropLocation || oldVL != verticalDropLocation) {
-            return true;
-        } else {
-            return false;
-        }
+        return oldHL != horizontalDropLocation || oldVL != verticalDropLocation;
     }
 
     protected void deEmphasis(boolean doLayout) {

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

@@ -426,11 +426,7 @@ public class VNotification extends VOverlay {
                 hide();
                 return false;
             }
-            if (temporaryStyle == STYLE_SYSTEM) {
-                return true;
-            } else {
-                return false;
-            }
+            return temporaryStyle == STYLE_SYSTEM;
         }
         // default
         switch (type) {

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

@@ -305,7 +305,6 @@ public class ComponentSizeValidator implements Serializable {
             this.component = component;
             this.info = info;
         }
-
     }
 
     private static Deque<ComponentInfo> getHeightAttributes(
@@ -435,7 +434,7 @@ public class ComponentSizeValidator implements Serializable {
     public static boolean parentCanDefineHeight(Component component) {
         Component parent = component.getParent();
         if (parent == null) {
-            // main window, valid situation
+            // main window
             return true;
         }
         if (parent.getHeight() < 0) {
@@ -446,37 +445,28 @@ public class ComponentSizeValidator implements Serializable {
             }
 
             if (parent instanceof AbstractOrderedLayout) {
-                boolean horizontal = true;
                 if (parent instanceof VerticalLayout) {
-                    horizontal = false;
-                }
-                if (horizontal && hasNonRelativeHeightComponent(
-                        (AbstractOrderedLayout) parent)) {
-                    return true;
-                } else {
                     return false;
                 }
+                return hasNonRelativeHeightComponent(
+                        (AbstractOrderedLayout) parent);
 
             } else if (parent instanceof GridLayout) {
                 GridLayout gl = (GridLayout) parent;
                 Area componentArea = gl.getComponentArea(component);
-                boolean rowHasHeight = false;
-                for (int row = componentArea.getRow1(); !rowHasHeight
-                        && row <= componentArea.getRow2(); row++) {
-                    for (int column = 0; !rowHasHeight
-                            && column < gl.getColumns(); column++) {
+                for (int row = componentArea.getRow1();
+                        row <= componentArea.getRow2(); row++) {
+                    for (int column = 0;
+                            column < gl.getColumns(); column++) {
                         Component c = gl.getComponent(column, row);
                         if (c != null) {
-                            rowHasHeight = !hasRelativeHeight(c);
+                            if (!hasRelativeHeight(c)) {
+                                return true;
+                            }
                         }
                     }
                 }
-                if (!rowHasHeight) {
-                    return false;
-                } else {
-                    // Other components define row height
-                    return true;
-                }
+                return false;
             } else if (isForm(parent)) {
                 /*
                  * If some other part of the form is not relative it determines
@@ -503,9 +493,8 @@ public class ComponentSizeValidator implements Serializable {
             // Relative height
             if (parent.getParent() != null) {
                 return parentCanDefineHeight(parent);
-            } else {
-                return true;
             }
+            return true;
         } else {
             // Absolute height
             return true;
@@ -516,7 +505,7 @@ public class ComponentSizeValidator implements Serializable {
      * Comparability form component which is defined in the different jar.
      *
      * TODO : Normally this logic shouldn't be here. But it means that the whole
-     * this class has wrong design and impementation and should be refactored.
+     * this class has wrong design and implementation and should be refactored.
      */
     private static boolean formHasNonRelativeWidthComponent(Component form) {
         HasComponents parent = (HasComponents) form;
@@ -553,7 +542,7 @@ public class ComponentSizeValidator implements Serializable {
     public static boolean parentCanDefineWidth(Component component) {
         Component parent = component.getParent();
         if (parent == null) {
-            // main window, valid situation
+            // main window
             return true;
         }
         if (parent instanceof Window) {
@@ -566,37 +555,25 @@ public class ComponentSizeValidator implements Serializable {
 
             if (parent instanceof AbstractOrderedLayout) {
                 AbstractOrderedLayout ol = (AbstractOrderedLayout) parent;
-                boolean horizontal = true;
-                if (ol instanceof VerticalLayout) {
-                    horizontal = false;
-                }
 
-                if (!horizontal && hasNonRelativeWidthComponent(ol)) {
-                    // valid situation, other components defined width
-                    return true;
-                } else {
-                    return false;
-                }
+                // VerticalLayout and a child defines height
+                return ol instanceof VerticalLayout
+                        && hasNonRelativeWidthComponent(ol);
             } else if (parent instanceof GridLayout) {
                 GridLayout gl = (GridLayout) parent;
                 Area componentArea = gl.getComponentArea(component);
-                boolean columnHasWidth = false;
-                for (int col = componentArea.getColumn1(); !columnHasWidth
-                        && col <= componentArea.getColumn2(); col++) {
-                    for (int row = 0; !columnHasWidth
-                            && row < gl.getRows(); row++) {
+                for (int col = componentArea.getColumn1();
+                        col <= componentArea.getColumn2(); col++) {
+                    for (int row = 0; row < gl.getRows(); row++) {
                         Component c = gl.getComponent(col, row);
                         if (c != null) {
-                            columnHasWidth = !hasRelativeWidth(c);
+                            if (!hasRelativeWidth(c)) {
+                                return true;
+                            }
                         }
                     }
                 }
-                if (!columnHasWidth) {
-                    return false;
-                } else {
-                    // Other components define column width
-                    return true;
-                }
+                return false;
             } else if (parent instanceof AbstractSplitPanel
                     || parent instanceof TabSheet
                     || parent instanceof CustomComponent) {
@@ -608,18 +585,11 @@ public class ComponentSizeValidator implements Serializable {
                 return false;
             } else if (parent instanceof Window) {
                 // Sub window can define width based on caption
-                if (parent.getCaption() != null
-                        && !parent.getCaption().isEmpty()) {
-                    return true;
-                } else {
-                    return false;
-                }
-            } else if (parent instanceof Panel) {
-                // TODO Panel should be able to define width based on caption
-                return false;
-            } else {
-                return true;
+                return parent.getCaption() != null
+                        && !parent.getCaption().isEmpty();
             }
+            // TODO Panel should be able to define width based on caption
+            return !(parent instanceof Panel);
         } else if (hasRelativeWidth(parent)) {
             // Relative width
             if (parent.getParent() == null) {

server/src/main/java/com/vaadin/server/widgetsetutils/ClassPathExplorer.java

@@ -58,13 +58,8 @@ public class ClassPathExplorer {
     /**
      * File filter that only accepts directories.
      */
-    private final static FileFilter DIRECTORIES_ONLY = (File f) -> {
-        if (f.exists() && f.isDirectory()) {
-            return true;
-        } else {
-            return false;
-        }
-    };
+    private final static FileFilter DIRECTORIES_ONLY = (File f) ->
+            f.exists() && f.isDirectory();
 
     /**
      * Contains information about widgetsets and themes found on the classpath

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

@@ -426,12 +426,9 @@ public abstract class AbstractComponent extends AbstractClientConnector
             return false;
         } else if (!super.isConnectorEnabled()) {
             return false;
-        } else if (getParent() instanceof SelectiveRenderer
-                && !((SelectiveRenderer) getParent()).isRendered(this)) {
-            return false;
-        } else {
-            return true;
         }
+        return !(getParent() instanceof SelectiveRenderer)
+            || ((SelectiveRenderer) getParent()).isRendered(this);
     }
 
     /*

shared/src/main/java/com/vaadin/shared/util/SharedUtil.java

@@ -93,13 +93,10 @@ public class SharedUtil implements Serializable {
         } else if (!Character.isUpperCase(camelCaseString.charAt(i - 1))) {
             // Word ends if previous char wasn't upper case
             return true;
-        } else if (i + 1 < camelCaseString.length()
-                && !Character.isUpperCase(camelCaseString.charAt(i + 1))) {
-            // Word ends if next char isn't upper case
-            return true;
-        } else {
-            return false;
         }
+        // Word ends if next char isn't upper case
+        return i + 1 < camelCaseString.length()
+                && !Character.isUpperCase(camelCaseString.charAt(i + 1));
     }
 
     /**