diff --git a/jdk/src/java.desktop/share/classes/com/sun/media/sound/WaveExtensibleFileReader.java b/jdk/src/java.desktop/share/classes/com/sun/media/sound/WaveExtensibleFileReader.java
index ba46be6cf5a..2dbcab81c7c 100644
--- a/jdk/src/java.desktop/share/classes/com/sun/media/sound/WaveExtensibleFileReader.java
+++ b/jdk/src/java.desktop/share/classes/com/sun/media/sound/WaveExtensibleFileReader.java
@@ -167,9 +167,9 @@ public final class WaveExtensibleFileReader extends AudioFileReader {
         for (int i = 0; i < allchannelnames.length; i++) {
             if ((channelmask & m) != 0L) {
                 if (i < channelnames.length) {
-                    sb.append(channelnames[i] + " ");
+                    sb.append(channelnames[i]).append(' ');
                 } else {
-                    sb.append(allchannelnames[i] + " ");
+                    sb.append(allchannelnames[i]).append(' ');
                 }
             }
             m *= 2L;
diff --git a/jdk/src/java.desktop/share/classes/javax/swing/GroupLayout.java b/jdk/src/java.desktop/share/classes/javax/swing/GroupLayout.java
index 45b25845674..196596c13bc 100644
--- a/jdk/src/java.desktop/share/classes/javax/swing/GroupLayout.java
+++ b/jdk/src/java.desktop/share/classes/javax/swing/GroupLayout.java
@@ -1213,15 +1213,15 @@ public class GroupLayout implements LayoutManager2 {
             registerComponents(horizontalGroup, HORIZONTAL);
             registerComponents(verticalGroup, VERTICAL);
         }
-        StringBuffer buffer = new StringBuffer();
-        buffer.append("HORIZONTAL\n");
-        createSpringDescription(buffer, horizontalGroup, "  ", HORIZONTAL);
-        buffer.append("\nVERTICAL\n");
-        createSpringDescription(buffer, verticalGroup, "  ", VERTICAL);
-        return buffer.toString();
+        StringBuilder sb = new StringBuilder();
+        sb.append("HORIZONTAL\n");
+        createSpringDescription(sb, horizontalGroup, "  ", HORIZONTAL);
+        sb.append("\nVERTICAL\n");
+        createSpringDescription(sb, verticalGroup, "  ", VERTICAL);
+        return sb.toString();
     }
 
-    private void createSpringDescription(StringBuffer buffer, Spring spring,
+    private void createSpringDescription(StringBuilder sb, Spring spring,
             String indent, int axis) {
         String origin = "";
         String padding = "";
@@ -1239,20 +1239,19 @@ public class GroupLayout implements LayoutManager2 {
             padding = ", userCreated=" + paddingSpring.getUserCreated() +
                     ", matches=" + paddingSpring.getMatchDescription();
         }
-        buffer.append(indent + spring.getClass().getName() + " " +
-                Integer.toHexString(spring.hashCode()) + " " +
-                origin +
-                ", size=" + spring.getSize() +
-                ", alignment=" + spring.getAlignment() +
-                " prefs=[" + spring.getMinimumSize(axis) +
-                " " + spring.getPreferredSize(axis) +
-                " " + spring.getMaximumSize(axis) +
-                padding + "]\n");
+        sb.append(indent).append(spring.getClass().getName()).append(' ')
+                .append(Integer.toHexString(spring.hashCode())).append(' ')
+                .append(origin).append(", size=").append(spring.getSize())
+                .append(", alignment=").append(spring.getAlignment())
+                .append(" prefs=[").append(spring.getMinimumSize(axis))
+                .append(' ').append(spring.getPreferredSize(axis)).append(' ')
+                .append(spring.getMaximumSize(axis)).append(padding)
+                .append("]\n");
         if (spring instanceof Group) {
             List<Spring> springs = ((Group)spring).springs;
             indent += "  ";
             for (int counter = 0; counter < springs.size(); counter++) {
-                createSpringDescription(buffer, springs.get(counter), indent,
+                createSpringDescription(sb, springs.get(counter), indent,
                         axis);
             }
         }
diff --git a/jdk/src/java.desktop/share/classes/javax/swing/JColorChooser.java b/jdk/src/java.desktop/share/classes/javax/swing/JColorChooser.java
index a2aa8146c6b..cfcdd51c0c6 100644
--- a/jdk/src/java.desktop/share/classes/javax/swing/JColorChooser.java
+++ b/jdk/src/java.desktop/share/classes/javax/swing/JColorChooser.java
@@ -543,17 +543,17 @@ public class JColorChooser extends JComponent implements Accessible {
      * @return  a string representation of this <code>JColorChooser</code>
      */
     protected String paramString() {
-        StringBuilder chooserPanelsString = new StringBuilder("");
-        for (int i=0; i<chooserPanels.length; i++) {
-            chooserPanelsString.append("[" + chooserPanels[i].toString()
-                                       + "]");
+        StringBuilder chooserPanelsString = new StringBuilder();
+        for (AbstractColorChooserPanel panel : chooserPanels) {
+            chooserPanelsString.append('[').append(panel)
+                               .append(']');
         }
-        String previewPanelString = (previewPanel != null ?
-                                     previewPanel.toString() : "");
+        String previewPanelString = (previewPanel != null ? previewPanel
+                .toString() : "");
 
-        return super.paramString() +
-        ",chooserPanels=" + chooserPanelsString.toString() +
-        ",previewPanel=" + previewPanelString;
+        return super.paramString() + ",chooserPanels="
+                + chooserPanelsString.toString() + ",previewPanel="
+                + previewPanelString;
     }
 
 /////////////////
diff --git a/jdk/src/java.desktop/share/classes/javax/swing/plaf/basic/BasicFileChooserUI.java b/jdk/src/java.desktop/share/classes/javax/swing/plaf/basic/BasicFileChooserUI.java
index 668467427f6..810aea8b923 100644
--- a/jdk/src/java.desktop/share/classes/javax/swing/plaf/basic/BasicFileChooserUI.java
+++ b/jdk/src/java.desktop/share/classes/javax/swing/plaf/basic/BasicFileChooserUI.java
@@ -1330,8 +1330,8 @@ public class BasicFileChooserUI extends FileChooserUI {
 
             for (Object obj : values) {
                 String val = ((obj == null) ? "" : obj.toString());
-                plainBuf.append(val + "\n");
-                htmlBuf.append("  <li>" + val + "\n");
+                plainBuf.append(val).append('\n');
+                htmlBuf.append("  <li>").append(val).append('\n');
             }
 
             // remove the last newline
diff --git a/jdk/src/java.desktop/share/classes/javax/swing/plaf/basic/BasicListUI.java b/jdk/src/java.desktop/share/classes/javax/swing/plaf/basic/BasicListUI.java
index fd4292e6350..77e24ca65ea 100644
--- a/jdk/src/java.desktop/share/classes/javax/swing/plaf/basic/BasicListUI.java
+++ b/jdk/src/java.desktop/share/classes/javax/swing/plaf/basic/BasicListUI.java
@@ -2948,8 +2948,8 @@ public class BasicListUI extends ListUI
                 for (int i = 0; i < values.length; i++) {
                     Object obj = values[i];
                     String val = ((obj == null) ? "" : obj.toString());
-                    plainStr.append(val + "\n");
-                    htmlStr.append("  <li>" + val + "\n");
+                    plainStr.append(val).append('\n');
+                    htmlStr.append("  <li>").append(val).append('\n');
                 }
 
                 // remove the last newline
diff --git a/jdk/src/java.desktop/share/classes/javax/swing/plaf/basic/BasicTableUI.java b/jdk/src/java.desktop/share/classes/javax/swing/plaf/basic/BasicTableUI.java
index bff514b57ff..25e13361d03 100644
--- a/jdk/src/java.desktop/share/classes/javax/swing/plaf/basic/BasicTableUI.java
+++ b/jdk/src/java.desktop/share/classes/javax/swing/plaf/basic/BasicTableUI.java
@@ -2230,11 +2230,11 @@ public class BasicTableUI extends TableUI
                     for (int col = 0; col < cols.length; col++) {
                         Object obj = table.getValueAt(rows[row], cols[col]);
                         String val = ((obj == null) ? "" : obj.toString());
-                        plainStr.append(val + "\t");
-                        htmlStr.append("  <td>" + val + "</td>\n");
+                        plainStr.append(val).append('\t');
+                        htmlStr.append("  <td>").append(val).append("</td>\n");
                     }
                     // we want a newline at the end of each line and not a tab
-                    plainStr.deleteCharAt(plainStr.length() - 1).append("\n");
+                    plainStr.deleteCharAt(plainStr.length() - 1).append('\n');
                     htmlStr.append("</tr>\n");
                 }
 
diff --git a/jdk/src/java.desktop/share/classes/javax/swing/plaf/basic/BasicTreeUI.java b/jdk/src/java.desktop/share/classes/javax/swing/plaf/basic/BasicTreeUI.java
index 4b783a02585..15517efc7b3 100644
--- a/jdk/src/java.desktop/share/classes/javax/swing/plaf/basic/BasicTreeUI.java
+++ b/jdk/src/java.desktop/share/classes/javax/swing/plaf/basic/BasicTreeUI.java
@@ -3618,8 +3618,8 @@ public class BasicTreeUI extends TreeUI
                     boolean leaf = model.isLeaf(node);
                     String label = getDisplayString(path, true, leaf);
 
-                    plainStr.append(label + "\n");
-                    htmlStr.append("  <li>" + label + "\n");
+                    plainStr.append(label).append('\n');
+                    htmlStr.append("  <li>").append(label).append('\n');
                 }
 
                 // remove the last newline
diff --git a/jdk/src/java.desktop/share/classes/sun/font/StandardGlyphVector.java b/jdk/src/java.desktop/share/classes/sun/font/StandardGlyphVector.java
index 77f2715e935..d48c99a6781 100644
--- a/jdk/src/java.desktop/share/classes/sun/font/StandardGlyphVector.java
+++ b/jdk/src/java.desktop/share/classes/sun/font/StandardGlyphVector.java
@@ -1894,9 +1894,9 @@ public class StandardGlyphVector extends GlyphVector {
             }
         }
         catch(Exception e) {
-            buf.append(" " + e.getMessage());
+            buf.append(' ').append(e.getMessage());
         }
-        buf.append("}");
+        buf.append('}');
 
         return buf;
     }