6900043: Add method to return line.separator property

Summary: Add System.lineSeparator(), returning getProperty("line.separator")
Reviewed-by: darcy

src/share/classes/java/lang/System.java

@@ -619,6 +619,20 @@ public final class System {
         return props;
     }
 
+    /**
+     * Returns the system-dependent line separator string.  It always
+     * returns the same value - the initial value of the {@linkplain
+     * #getProperty(String) system property} {@code line.separator}.
+     *
+     * <p>On UNIX systems, it returns {@code "\n"}; on Microsoft
+     * Windows systems it returns {@code "\r\n"}.
+     */
+    public static String lineSeparator() {
+        return lineSeparator;
+    }
+
+    private static String lineSeparator;
+
     /**
      * Sets the system properties to the <code>Properties</code>
      * argument.
@@ -1104,6 +1118,7 @@ public final class System {
     private static void initializeSystemClass() {
         props = new Properties();
         initProperties(props);
+        lineSeparator = props.getProperty("line.separator");
         sun.misc.Version.init();
 
         // Workaround until DownloadManager initialization is revisited.
@@ -1192,7 +1207,7 @@ public final class System {
     }
 
     /* returns the class of the caller. */
-    static Class getCallerClass() {
+    static Class<?> getCallerClass() {
         // NOTE use of more generic Reflection.getCallerClass()
         return Reflection.getCallerClass(3);
     }

src/share/classes/java/util/Formatter.java

@@ -2552,9 +2552,6 @@ public final class Formatter implements Closeable, Flushable {
         private boolean dt = false;
         private char c;
 
-        // cache the line separator
-        private String ls;
-
         private int index(String s) {
             if (s != null) {
                 try {
@@ -2702,9 +2699,7 @@ public final class Formatter implements Closeable, Flushable {
                 printHashCode(arg);
                 break;
             case Conversion.LINE_SEPARATOR:
-                if (ls == null)
-                    ls = System.getProperty("line.separator");
-                a.append(ls);
+                a.append(System.lineSeparator());
                 break;
             case Conversion.PERCENT_SIGN:
                 a.append('%');