1 /* 2 * Copyright (c) 2015, 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 /** 25 * @test 26 * @summary Calculates Fibonacci numbers "recursively" via threads and compares 27 * the result with the classical calculation. 28 * This test is skipped on 32-bit Windows: limited virtual space on Win-32 29 * make this test inherently unstable on Windows with 32-bit VM data model. 30 * @requires !(os.family == "windows" & sun.arch.data.model == "32") 31 * @library /testlibrary 32 * @run main Fibonacci 15 33 */ 34 35 import com.oracle.java.testlibrary.Asserts; 36 37 public class Fibonacci extends Thread { 38 private int index; 39 private int value; 40 private Fibonacci left; 41 private Fibonacci right; 42 43 public Fibonacci(int i) { 44 index = i; 45 } 46 47 private int getValue() { 48 return value; 49 } 50 51 @Override 52 public void run() { 53 if (index == 0 || index == 1) { 54 // base cases, 0 Fibonacci number = 0, 1 Fibonacci number = 1 55 value = index; 56 } else { 57 // inductive cases 58 left = new Fibonacci(index - 2); 59 right = new Fibonacci(index - 1); 60 left.start(); 61 right.start(); 62 try { 63 left.join(); 64 right.join(); 65 } catch (InterruptedException e) { 66 throw new Error("InterruptedException for index " + index, e); 67 } 68 // compute and terminate 69 value = left.getValue() + right.getValue(); 70 } 71 } 72 73 public static int traditionalFibonacci(int n) { 74 int n1 = 0, n2 = 1, nn = 0; 75 76 if (n == 0 || n == 1) { 77 nn = n; 78 } 79 80 for (int i = 1; i < n; ++i) { 81 nn = n2 + n1; 82 n1 = n2; 83 n2 = nn; 84 } 85 return nn; 86 } 87 88 public static void main(String[] args) throws Error,AssertionError { 89 int expected; 90 int number; 91 Fibonacci recursiveFibonacci; 92 93 if (args.length != 1) { 94 throw new Error("Error: args.length must be 1"); 95 } 96 97 number = Integer.parseInt(args[0]); 98 recursiveFibonacci = new Fibonacci(number); 99 100 recursiveFibonacci.start(); 101 try { 102 recursiveFibonacci.join(); 103 } catch (InterruptedException e) { 104 throw new Error("InterruptedException in main thread", e); 105 } 106 107 expected = traditionalFibonacci(number); 108 109 System.out.println("Fibonacci[" + number + "] = " + expected); 110 111 Asserts.assertEQ(recursiveFibonacci.getValue(), expected, 112 "Unexpected calculated value: " + recursiveFibonacci.getValue() + " expected " + expected ); 113 } 114 }