6924259: Remove offset and count fields from java.lang.String

Summary: Removes the use of shared character array buffers by String along with the two fields needed to support the use of shared buffers.
Reviewed-by: alanb, mduigou, forax, briangoetz
Contributed-by: brian.doherty@oracle.com

src/share/classes/java/lang/Integer.java

@@ -381,7 +381,7 @@ public final class Integer extends Number implements Comparable<Integer> {
         int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
         char[] buf = new char[size];
         getChars(i, size, buf);
-        return new String(0, size, buf);
+        return new String(buf, true);
     }
 
     /**

src/share/classes/java/lang/Long.java

@@ -373,7 +373,7 @@ public final class Long extends Number implements Comparable<Long> {
         int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
         char[] buf = new char[size];
         getChars(i, size, buf);
-        return new String(0, size, buf);
+        return new String(buf, true);
     }
 
     /**

src/share/classes/java/lang/StringCoding.java

@@ -250,6 +250,7 @@ class StringCoding {
     static char[] decode(byte[] ba, int off, int len) {
         String csn = Charset.defaultCharset().name();
         try {
+            // use charset name decode() variant which provides caching.
             return decode(csn, ba, off, len);
         } catch (UnsupportedEncodingException x) {
             warnUnsupportedCharset(csn);
@@ -382,6 +383,7 @@ class StringCoding {
     static byte[] encode(char[] ca, int off, int len) {
         String csn = Charset.defaultCharset().name();
         try {
+            // use charset name encode() variant which provides caching.
             return encode(csn, ca, off, len);
         } catch (UnsupportedEncodingException x) {
             warnUnsupportedCharset(csn);