1 /*
   2  * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 import java.util.Arrays;
  25 import java.util.SystemRandom;
  26 
  27 /*
  28  * @test
  29  * @summary Test for java.util.SystemRandom
  30  */
  31 public class SystemRandomTest {
  32     public static void main(String[] args) {
  33         System.out.println("SystemRandomTest... (8 bytes / invocation)");
  34         byte[] bytes = new byte[8];
  35         long t0 = System.nanoTime();
  36         try (SystemRandom sr = SystemRandom.newInstance()) {
  37             sr.getBytes(bytes);
  38             long t1 = System.nanoTime();
  39             System.out.println("1st invocation: " +
  40                 (t1 - t0) + " ns, result: " + Arrays.toString(bytes));
  41 
  42             final int N = 1_000_000;
  43 
  44             t0 = System.nanoTime();
  45             for (int i = 0; i < N; i++) {
  46                 sr.getBytes(bytes);
  47             }
  48             t1 = System.nanoTime();
  49 
  50             System.out.println("Following " + N + " invocations: " +
  51                 ((double)(t1 - t0)/1e9d) + " s, (" +
  52                 ((t1-t0)/N) + " ns/invocation)");
  53         }
  54     }
  55 }