Use single character for StringBuilder.append (#10102)

12 files changed, 60 insertions, 58 deletions

diff --git a/server/src/main/java/com/vaadin/navigator/Navigator.java b/server/src/main/java/com/vaadin/navigator/Navigator.java
index d65bad9db7..a21cdbcaac 100644
--- a/server/src/main/java/com/vaadin/navigator/Navigator.java
+++ b/server/src/main/java/com/vaadin/navigator/Navigator.java
@@ -159,7 +159,7 @@ public class Navigator implements Serializable {
             if (!ui.getUiRootPath().endsWith("/")) {
                 // make sure there is a '/' between the root path and the
                 // navigation state.
-                sb.append("/");
+                sb.append('/');
             }
             sb.append(state);
             URI location = ui.getPage().getLocation();
diff --git a/server/src/main/java/com/vaadin/server/ComponentSizeValidator.java b/server/src/main/java/com/vaadin/server/ComponentSizeValidator.java
index f65fc610c9..efbce4eeca 100644
--- a/server/src/main/java/com/vaadin/server/ComponentSizeValidator.java
+++ b/server/src/main/java/com/vaadin/server/ComponentSizeValidator.java
@@ -210,7 +210,7 @@ public class ComponentSizeValidator implements Serializable {
 
         public void reportErrors(StringBuilder clientJSON,
                 PrintStream serverErrorStream) {
-            clientJSON.append("{");
+            clientJSON.append('{');
 
             Component parent = component.getParent();
             String paintableId = component.getConnectorId();
@@ -282,16 +282,16 @@ public class ComponentSizeValidator implements Serializable {
                 boolean first = true;
                 for (InvalidLayout subError : subErrors) {
                     if (!first) {
-                        clientJSON.append(",");
+                        clientJSON.append(',');
                     } else {
                         first = false;
                     }
                     subError.reportErrors(clientJSON, serverErrorStream);
                 }
-                clientJSON.append("]");
+                clientJSON.append(']');
                 serverErrorStream.println("<< Sub erros");
             }
-            clientJSON.append("}");
+            clientJSON.append('}');
         }
     }
 
@@ -385,7 +385,7 @@ public class ComponentSizeValidator implements Serializable {
         err.append("- ");
 
         err.append(component.getClass().getSimpleName());
-        err.append("/").append(Integer.toHexString(component.hashCode()));
+        err.append('/').append(Integer.toHexString(component.hashCode()));
 
         if (component.getCaption() != null) {
             err.append(" \"");
@@ -399,8 +399,8 @@ public class ComponentSizeValidator implements Serializable {
         }
 
         if (createLoc != null) {
-            err.append(", created at (").append(createLoc.file).append(":")
-                    .append(createLoc.lineNumber).append(")");
+            err.append(", created at (").append(createLoc.file).append(':')
+                    .append(createLoc.lineNumber).append(')');
 
         }
 
@@ -408,11 +408,11 @@ public class ComponentSizeValidator implements Serializable {
             err.append(" (");
             err.append(attribute);
             if (sizeLoc != null) {
-                err.append(", set at (").append(sizeLoc.file).append(":")
-                        .append(sizeLoc.lineNumber).append(")");
+                err.append(", set at (").append(sizeLoc.file).append(':')
+                        .append(sizeLoc.lineNumber).append(')');
             }
 
-            err.append(")");
+            err.append(')');
         }
         err.append("\n");
 
@@ -452,10 +452,9 @@ public class ComponentSizeValidator implements Serializable {
             } else if (parent instanceof GridLayout) {
                 GridLayout gl = (GridLayout) parent;
                 Area componentArea = gl.getComponentArea(component);
-                for (int row = componentArea.getRow1();
-                        row <= componentArea.getRow2(); row++) {
-                    for (int column = 0;
-                            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) {
                             if (!hasRelativeHeight(c)) {
@@ -560,8 +559,8 @@ public class ComponentSizeValidator implements Serializable {
             } else if (parent instanceof GridLayout) {
                 GridLayout gl = (GridLayout) parent;
                 Area componentArea = gl.getComponentArea(component);
-                for (int col = componentArea.getColumn1();
-                        col <= componentArea.getColumn2(); col++) {
+                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) {
diff --git a/server/src/main/java/com/vaadin/server/JsonPaintTarget.java b/server/src/main/java/com/vaadin/server/JsonPaintTarget.java
index 3be04fc2c4..3fef4926d3 100644
--- a/server/src/main/java/com/vaadin/server/JsonPaintTarget.java
+++ b/server/src/main/java/com/vaadin/server/JsonPaintTarget.java
@@ -408,7 +408,7 @@ public class JsonPaintTarget implements PaintTarget {
         sb.append("\"");
         sb.append(name);
         sb.append("\":");
-        sb.append("{");
+        sb.append('{');
         for (Iterator<?> it = value.keySet().iterator(); it.hasNext();) {
             Object key = it.next();
             Object mapValue = value.get(key);
@@ -429,10 +429,10 @@ public class JsonPaintTarget implements PaintTarget {
                 sb.append("\"");
             }
             if (it.hasNext()) {
-                sb.append(",");
+                sb.append(',');
             }
         }
-        sb.append("}");
+        sb.append('}');
 
         tag.addAttribute(sb.toString());
     }
@@ -448,13 +448,13 @@ public class JsonPaintTarget implements PaintTarget {
         buf.append("\"").append(name).append("\":[");
         for (int i = 0; i < values.length; i++) {
             if (i > 0) {
-                buf.append(",");
+                buf.append(',');
             }
             buf.append("\"");
             buf.append(escapeJSON(values[i].toString()));
             buf.append("\"");
         }
-        buf.append("]");
+        buf.append(']');
         tag.addAttribute(buf.toString());
     }
 
@@ -753,7 +753,7 @@ public class JsonPaintTarget implements PaintTarget {
                 data.append(attributesAsJsonObject());
                 data.append(getData());
                 // Writes the end (closing) tag
-                data.append("]");
+                data.append(']');
                 tagClosed = true;
             }
         }
@@ -774,7 +774,7 @@ public class JsonPaintTarget implements PaintTarget {
         }
 
         public void closeChildrenArray() {
-            // append("]");
+            // append(']');
             // firstField = false;
         }
 
@@ -821,17 +821,17 @@ public class JsonPaintTarget implements PaintTarget {
         private String attributesAsJsonObject() {
             final StringBuilder buf = new StringBuilder();
             buf.append(startField());
-            buf.append("{");
+            buf.append('{');
             for (final Iterator<Object> iter = attr.iterator(); iter
                     .hasNext();) {
                 final String element = (String) iter.next();
                 buf.append(element);
                 if (iter.hasNext()) {
-                    buf.append(",");
+                    buf.append(',');
                 }
             }
             buf.append(tag.variablesAsJsonObject());
-            buf.append("}");
+            buf.append('}');
             return buf.toString();
         }
 
@@ -851,10 +851,10 @@ public class JsonPaintTarget implements PaintTarget {
                 final Variable element = (Variable) iter.next();
                 buf.append(element.getJsonPresentation());
                 if (iter.hasNext()) {
-                    buf.append(",");
+                    buf.append(',');
                 }
             }
-            buf.append("}");
+            buf.append('}');
             return buf.toString();
         }
     }
@@ -972,10 +972,10 @@ public class JsonPaintTarget implements PaintTarget {
                 sb.append("\"");
                 i++;
                 if (i < value.length) {
-                    sb.append(",");
+                    sb.append(',');
                 }
             }
-            sb.append("]");
+            sb.append(']');
             return sb.toString();
         }
     }
diff --git a/server/src/main/java/com/vaadin/server/VaadinServlet.java b/server/src/main/java/com/vaadin/server/VaadinServlet.java
index edfbd1cc28..fff04caf45 100644
--- a/server/src/main/java/com/vaadin/server/VaadinServlet.java
+++ b/server/src/main/java/com/vaadin/server/VaadinServlet.java
@@ -1510,7 +1510,7 @@ public class VaadinServlet extends HttpServlet implements Constants {
             } else {
                 safe.append("&#");
                 safe.append((int) c);
-                safe.append(";");
+                safe.append(';');
             }
         }
 
diff --git a/server/src/main/java/com/vaadin/ui/AbsoluteLayout.java b/server/src/main/java/com/vaadin/ui/AbsoluteLayout.java
index beedc52a45..58e937e8a2 100644
--- a/server/src/main/java/com/vaadin/ui/AbsoluteLayout.java
+++ b/server/src/main/java/com/vaadin/ui/AbsoluteLayout.java
@@ -676,20 +676,20 @@ public class AbsoluteLayout extends AbstractLayout
             Component newChild = designContext.readDesign(childComponent);
             StringBuilder css = new StringBuilder();
             if (attr.hasKey(ATTR_TOP)) {
-                css.append("top:").append(attr.get(ATTR_TOP)).append(";");
+                css.append("top:").append(attr.get(ATTR_TOP)).append(';');
             }
             if (attr.hasKey(ATTR_RIGHT)) {
-                css.append("right:").append(attr.get(ATTR_RIGHT)).append(";");
+                css.append("right:").append(attr.get(ATTR_RIGHT)).append(';');
             }
             if (attr.hasKey(ATTR_BOTTOM)) {
-                css.append("bottom:").append(attr.get(ATTR_BOTTOM)).append(";");
+                css.append("bottom:").append(attr.get(ATTR_BOTTOM)).append(';');
             }
             if (attr.hasKey(ATTR_LEFT)) {
-                css.append("left:").append(attr.get(ATTR_LEFT)).append(";");
+                css.append("left:").append(attr.get(ATTR_LEFT)).append(';');
             }
             if (attr.hasKey(ATTR_Z_INDEX)) {
                 css.append("z-index:").append(attr.get(ATTR_Z_INDEX))
-                        .append(";");
+                        .append(';');
             }
             addComponent(newChild, css.toString());
         }
diff --git a/server/src/main/java/com/vaadin/ui/GridLayout.java b/server/src/main/java/com/vaadin/ui/GridLayout.java
index cc043927e9..b4d97018ce 100644
--- a/server/src/main/java/com/vaadin/ui/GridLayout.java
+++ b/server/src/main/java/com/vaadin/ui/GridLayout.java
@@ -652,14 +652,14 @@ public class GridLayout extends AbstractLayout
                 sb.append(component.getCaption());
                 sb.append("\"");
             }
-            sb.append(")");
+            sb.append(')');
             sb.append(" is already added to ");
             sb.append(existingArea.childData.column1);
-            sb.append(",");
+            sb.append(',');
             sb.append(existingArea.childData.column1);
-            sb.append(",");
+            sb.append(',');
             sb.append(existingArea.childData.row1);
-            sb.append(",");
+            sb.append(',');
             sb.append(existingArea.childData.row2);
             sb.append("(column1, column2, row1, row2).");
 
diff --git a/server/src/main/java/com/vaadin/ui/UI.java b/server/src/main/java/com/vaadin/ui/UI.java
index 5d27c1de74..e8b9198111 100644
--- a/server/src/main/java/com/vaadin/ui/UI.java
+++ b/server/src/main/java/com/vaadin/ui/UI.java
@@ -214,13 +214,13 @@ public abstract class UI extends AbstractSingleComponentContainer
                     .validateLayouts(UI.this);
             StringBuilder json = new StringBuilder();
             json.append("{\"invalidLayouts\":");
-            json.append("[");
+            json.append('[');
 
             if (invalidSizes != null) {
                 boolean first = true;
                 for (InvalidLayout invalidSize : invalidSizes) {
                     if (!first) {
-                        json.append(",");
+                        json.append(',');
                     } else {
                         first = false;
                     }
diff --git a/server/src/main/java/com/vaadin/ui/components/grid/GridDragSource.java b/server/src/main/java/com/vaadin/ui/components/grid/GridDragSource.java
index 128e8bcb97..cf5051abb4 100644
--- a/server/src/main/java/com/vaadin/ui/components/grid/GridDragSource.java
+++ b/server/src/main/java/com/vaadin/ui/components/grid/GridDragSource.java
@@ -61,14 +61,15 @@ public class GridDragSource<T> extends DragSourceExtension<Grid<T>> {
     /**
      * Default drag data generator for Grid. It creates a list of row values
      * separated by a tabulator character ({@code \t}).
+     * 
      * <pre>
-     *      "column1_value\tcolumn2_value\t ... columnN_value"
+     * "column1_value\tcolumn2_value\t ... columnN_value"
      * </pre>
      */
     private final SerializableFunction<T, String> defaultGridGenerator = item -> {
         StringBuilder generatedValue = new StringBuilder();
         getParent().getColumns().forEach(column -> {
-            generatedValue.append("\t");    // Tab separated values
+            generatedValue.append("\t"); // Tab separated values
             generatedValue.append(column.getValueProvider().apply(item));
         });
         return generatedValue.substring(1);
@@ -92,8 +93,8 @@ public class GridDragSource<T> extends DragSourceExtension<Grid<T>> {
         generatorFunctions = new HashMap<>();
 
         // Set default generator function for "text" parameter
-        generatorFunctions
-                .put(DragSourceState.DATA_TYPE_TEXT, defaultGridGenerator);
+        generatorFunctions.put(DragSourceState.DATA_TYPE_TEXT,
+                defaultGridGenerator);
     }
 
     @Override
@@ -163,6 +164,7 @@ public class GridDragSource<T> extends DragSourceExtension<Grid<T>> {
      * type} data.
      * <p>
      * Example, building a JSON object that contains the item's values:
+     * 
      * <pre>
      *     dragSourceExtension.setDragDataGenerator("application/json", item ->
      * {
@@ -181,12 +183,13 @@ public class GridDragSource<T> extends DragSourceExtension<Grid<T>> {
      * </pre>
      *
      * @param type
-     *         Type of the generated data. The generated value will be
-     *         accessible during drop using this type.
+     *            Type of the generated data. The generated value will be
+     *            accessible during drop using this type.
      * @param generator
-     *         Function to be executed on row data generation.
+     *            Function to be executed on row data generation.
      */
-    public void setDragDataGenerator(String type, SerializableFunction<T, String> generator) {
+    public void setDragDataGenerator(String type,
+            SerializableFunction<T, String> generator) {
         generatorFunctions.put(type, generator);
     }
 
@@ -194,7 +197,7 @@ public class GridDragSource<T> extends DragSourceExtension<Grid<T>> {
      * Remove the generator function set for the given type.
      *
      * @param type
-     *         Type of the generator to be removed.
+     *            Type of the generator to be removed.
      */
     public void clearDragDataGenerator(String type) {
         generatorFunctions.remove(type);
@@ -204,7 +207,7 @@ public class GridDragSource<T> extends DragSourceExtension<Grid<T>> {
      * Returns the drag data generator function for the given type.
      *
      * @param type
-     *         Type of the generated data.
+     *            Type of the generated data.
      * @return Drag data generator function for the given type.
      */
     public SerializableFunction<T, String> getDragDataGenerator(String type) {
diff --git a/server/src/main/java/com/vaadin/ui/declarative/Design.java b/server/src/main/java/com/vaadin/ui/declarative/Design.java
index 78288737a0..761ce3c355 100644
--- a/server/src/main/java/com/vaadin/ui/declarative/Design.java
+++ b/server/src/main/java/com/vaadin/ui/declarative/Design.java
@@ -302,7 +302,7 @@ public class Design implements Serializable {
                 Character c = className.charAt(i);
                 if (Character.isUpperCase(c)) {
                     if (i > 0) {
-                        result.append("-");
+                        result.append('-');
                     }
                     result.append(Character.toLowerCase(c));
                 } else {
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 cdf0c6aaee..5b5887316c 100644
--- a/server/src/main/java/com/vaadin/ui/declarative/DesignAttributeHandler.java
+++ b/server/src/main/java/com/vaadin/ui/declarative/DesignAttributeHandler.java
@@ -328,7 +328,7 @@ public class DesignAttributeHandler implements Serializable {
         StringBuilder builder = new StringBuilder();
         for (int i = 0; i < words.length; i++) {
             if (builder.length() != 0) {
-                builder.append("-");
+                builder.append('-');
             }
             builder.append(words[i].toLowerCase());
         }
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 aade7e80b7..63f509c9ce 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
@@ -166,13 +166,13 @@ public class DesignShortcutActionConverter
         // handle modifiers
         if (value.getModifiers() != null) {
             for (int modifier : value.getModifiers()) {
-                sb.append(getStringForKeycode(modifier)).append("-");
+                sb.append(getStringForKeycode(modifier)).append('-');
             }
         }
         // handle keycode
         sb.append(getStringForKeycode(value.getKeyCode()));
         if (value.getCaption() != null) {
-            sb.append(" ").append(value.getCaption());
+            sb.append(' ').append(value.getCaption());
         }
         return sb.toString();
     }
diff --git a/server/src/main/java/com/vaadin/util/ConnectorHelper.java b/server/src/main/java/com/vaadin/util/ConnectorHelper.java
index 46b4ba4bf1..480724ae5e 100644
--- a/server/src/main/java/com/vaadin/util/ConnectorHelper.java
+++ b/server/src/main/java/com/vaadin/util/ConnectorHelper.java
@@ -92,7 +92,7 @@ public class ConnectorHelper {
                 topClass = topClass.getEnclosingClass();
             }
             builder.append(connectorClass.getName());
-            builder.append("(");
+            builder.append('(');
             builder.append(topClass.getSimpleName());
             builder.append(".java:1)");
         }