1 /*
   2  * Copyright (c) 2019, 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 package org.openjdk.bench.java.lang;
  25 
  26 import org.openjdk.jmh.annotations.*;
  27 import java.util.concurrent.TimeUnit;
  28 
  29 @BenchmarkMode(Mode.AverageTime)
  30 @OutputTimeUnit(TimeUnit.NANOSECONDS)
  31 @Fork(value = 3)
  32 @Warmup(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
  33 @Measurement(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
  34 @State(Scope.Benchmark)
  35 public class StringSubstring {
  36 
  37     public String s = new String("An arbitrary string that happened to be of length 52");
  38 
  39     @Benchmark
  40     public String from26toEnd0() {
  41         return s.substring(26);
  42     }
  43 
  44     @Benchmark
  45     public String from26toEnd1() {
  46         return s.substring(26, s.length());
  47     }
  48 
  49     /**
  50      * An empty substring should not allocate a new String
  51      */
  52     @Benchmark
  53     public String empty() {
  54         return s.substring(17, 17);
  55     }
  56 }