src/java.base/share/classes/java/io/InputStream.java

*** 27,36 ****
--- 27,37 ----
  
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.List;
  import java.util.Objects;
+ import jdk.internal.io.IOSupport;
  
  /**
   * This abstract class is the superclass of all classes representing
   * an input stream of bytes.
   *
*** 540,554 ****
       *
       * @since 9
       */
      public long transferTo(OutputStream out) throws IOException {
          Objects.requireNonNull(out, "out");
!         long transferred = 0;
!         byte[] buffer = new byte[DEFAULT_BUFFER_SIZE];
!         int read;
!         while ((read = this.read(buffer, 0, DEFAULT_BUFFER_SIZE)) >= 0) {
!             out.write(buffer, 0, read);
!             transferred += read;
!         }
!         return transferred;
      }
  }
--- 541,548 ----
       *
       * @since 9
       */
      public long transferTo(OutputStream out) throws IOException {
          Objects.requireNonNull(out, "out");
!         return IOSupport.copy(this, out);
      }
  }