src/java.base/share/classes/java/lang/String.java

rev 49004 : 8197594: String#repeat

*** 2961,2970 ****
--- 2961,3016 ----
       *          guaranteed to be from a pool of unique strings.
       * @jls 3.10.5 String Literals
       */
      public native String intern();
  
+     /**
+      * Returns a string whose value is the concatenation of this
+      * string repeated {@code count} times.
+      * <p>
+      * If count or length is zero then the empty string is returned.
+      * <p>
+      * This method may be used to create space padding for
+      * formatting text or zero padding for formatting numbers.
+      * @param   count number of times to repeat
+      * @return  A string composed of this string repeated
+      *          {@code count} times or the empty string if count
+      *          or length is zero.
+      * @throws  IllegalArgumentException if the {@code count} is
+      *          negative.
+      */
+     public String repeat(int count) {
+         if (count < 0) {
+             throw new IllegalArgumentException("count is negative, " + count);
+         }
+         if (count == 1) {
+             return this;
+         }
+         final int len = value.length;
+         if (len == 0 || count == 0) {
+             return "";
+         }
+         if (len == 1) {
+             final byte[] single = new byte[count];
+             Arrays.fill(single, value[0]);
+             return new String(single, coder);
+         }
+         if (Integer.MAX_VALUE / count < len) {
+             throw new OutOfMemoryError();
+         }
+         final int limit = len * count;
+         final byte[] multiple = new byte[limit];
+         System.arraycopy(value, 0, multiple, 0, len);
+         int copied = len;
+         for (int next = copied << 1; next < limit && 0 < next; next = next << 1) {
+             System.arraycopy(multiple, 0, multiple, copied, copied);
+             copied = next;
+         }
+         System.arraycopy(multiple, 0, multiple, copied, limit - copied);
+         return new String(multiple, coder);
+     }
+ 
      ////////////////////////////////////////////////////////////////
  
      /**
       * Copy character bytes from this string into dst starting at dstBegin.
       * This method doesn't perform any range checking.