| /* |
| * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| /** |
| * @test |
| * @summary Calculates Fibonacci numbers "recursively" via threads and compares |
| * the result with the classical calculation. |
| * This test is skipped on 32-bit Windows: limited virtual space on Win-32 |
| * make this test inherently unstable on Windows with 32-bit VM data model. |
| * @requires !(os.family == "windows" & sun.arch.data.model == "32") |
| * @modules java.base/jdk.internal.misc |
| * @library /test/lib |
| * @run main/othervm Fibonacci 15 |
| */ |
| |
| import jdk.test.lib.Asserts; |
| |
| public class Fibonacci extends Thread { |
| private int index; |
| private int value; |
| private Fibonacci left; |
| private Fibonacci right; |
| |
| public Fibonacci(int i) { |
| index = i; |
| } |
| |
| private int getValue() { |
| return value; |
| } |
| |
| @Override |
| public void run() { |
| if (index == 0 || index == 1) { |
| // base cases, 0 Fibonacci number = 0, 1 Fibonacci number = 1 |
| value = index; |
| } else { |
| // inductive cases |
| left = new Fibonacci(index - 2); |
| right = new Fibonacci(index - 1); |
| left.start(); |
| right.start(); |
| try { |
| left.join(); |
| right.join(); |
| } catch (InterruptedException e) { |
| throw new Error("InterruptedException for index " + index, e); |
| } |
| // compute and terminate |
| value = left.getValue() + right.getValue(); |
| } |
| } |
| |
| public static int traditionalFibonacci(int n) { |
| int n1 = 0, n2 = 1, nn = 0; |
| |
| if (n == 0 || n == 1) { |
| nn = n; |
| } |
| |
| for (int i = 1; i < n; ++i) { |
| nn = n2 + n1; |
| n1 = n2; |
| n2 = nn; |
| } |
| return nn; |
| } |
| |
| public static void main(String[] args) throws Error,AssertionError { |
| int expected; |
| int number; |
| Fibonacci recursiveFibonacci; |
| |
| if (args.length != 1) { |
| throw new Error("Error: args.length must be 1"); |
| } |
| |
| number = Integer.parseInt(args[0]); |
| recursiveFibonacci = new Fibonacci(number); |
| |
| recursiveFibonacci.start(); |
| try { |
| recursiveFibonacci.join(); |
| } catch (InterruptedException e) { |
| throw new Error("InterruptedException in main thread", e); |
| } |
| |
| expected = traditionalFibonacci(number); |
| |
| System.out.println("Fibonacci[" + number + "] = " + expected); |
| |
| Asserts.assertEQ(recursiveFibonacci.getValue(), expected, |
| "Unexpected calculated value: " + recursiveFibonacci.getValue() + " expected " + expected ); |
| } |
| } |