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Add a method to detect Java 3D extensions
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‎src/main/java/org/scijava/java3d/DefaultJava3DService.java‎

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/*
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* #%L
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* Utility classes for working with Java 3D.
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* %%
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* Copyright (C) 2015 Board of Regents of the University of
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* Wisconsin-Madison.
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* %%
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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* #L%
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*/
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package org.scijava.java3d;
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import java.io.File;
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import java.util.ArrayList;
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import java.util.List;
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import org.scijava.plugin.Plugin;
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import org.scijava.service.AbstractService;
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import org.scijava.service.Service;
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/**
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* Default service for working with Java 3D.
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*
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* @author Curtis Rueden
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*/
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@Plugin(type = Service.class)
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public class DefaultJava3DService extends AbstractService implements
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Java3DService
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{
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@Override
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public List<File> getLibExtLocations() {
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final ArrayList<File> files = new ArrayList<File>();
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final String extDirs = System.getProperty("java.ext.dirs");
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if (extDirs == null) return files;
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for (final String dir : extDirs.split(":")) {
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checkLibExtDirectory(files, dir);
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}
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return files;
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}
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// -- Helper methods --
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private void checkLibExtDirectory(final ArrayList<File> files,
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final String dir)
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{
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checkFile(files, new File(dir, "j3dcore.jar"));
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checkFile(files, new File(dir, "vecmath.jar"));
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checkFile(files, new File(dir, "j3dutils.jar"));
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}
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private void checkFile(ArrayList<File> files, File file) {
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if (file.exists()) files.add(file);
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}
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}

‎src/main/java/org/scijava/java3d/Java3DService.java‎

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package org.scijava.java3d;
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import java.io.File;
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import java.util.List;
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import org.scijava.service.SciJavaService;
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import org.scijava.ui.UIService;
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/**
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* Interface for services which work with Java 3D.
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*
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* <p>
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* Historically, Java 3D was installed as an extension to the Java Runtime
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* Environment, meaning that JAR files and native libraries were placed in the
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* {@code lib/ext} directory of the JRE installation, or manually appended to
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* the Java extensions via the {@code java.ext.dirs} system property.
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* </p>
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* <p>
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* However, that approach has many downsides:
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* </p>
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* <ul>
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* <li>Users must install Java 3D manually, independent of the application.</li>
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* <li>Thus, at runtime, the application cannot manage the version of Java 3D in
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* the same was that it manages versions of its regular dependencies.</li>
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* <li>Similarly, at build time, the Java 3D dependency must be treated
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* specially (e.g., with Maven, using {@code provided} scope in the POM).</li>
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* </ul>
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* <p>
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* Failure to manage Java 3D installations as needed can result in cryptic
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* version-skew-related error messages, such as {@link NoSuchMethodError} or
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* even native-library-related errors. This situation is especially prevalent on
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* OS X, where Java 3D 1.3 was pre-installed in
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* {@code /System/Library/Java/Extensions} on older versions of the OS, and left
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* in place after OS upgrades (despite Java itself being uninstalled).
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* </p>
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* <p>
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* These days, Java 3D is built on top of JOGL, and <a
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* href="https://github.com/hharrison/java3d-core">available on GitHub</a>. But
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* old installations of Java 3D still lurk, waiting to disrupt applications at
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* runtime: libraries present on the Java extensions path take precedence over
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* those on the regular class path.
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* </p>
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* <p>
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* This service mitigates the issue by warning users (via
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* {@link UIService#showDialog}) if any Java 3D installations are detected as
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* Java extensions, and asking the user to clean them up before proceeding.
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* Consequently, applications can now use the modern JOGL version of Java 3D,
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* without worrying about obsolete versions of Java 3D interfering at runtime.
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* </p>
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*
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* @author Curtis Rueden
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*/
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public interface Java3DService extends SciJavaService {
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/**
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* Gets the locations where Java 3D is installed as an extension.
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*
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* @return a {@link List} of directories containing Java 3D libraries.
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*/
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List<File> getLibExtLocations();
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}

‎src/test/java/org/scijava/java3d/Java3DServiceTest.java‎

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package org.scijava.java3d;
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import static org.junit.Assert.assertEquals;
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import java.io.File;
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import java.io.IOException;
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import java.util.HashSet;
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import org.junit.After;
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import org.junit.Before;
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import org.junit.Test;
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import org.scijava.Context;
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import org.scijava.util.FileUtils;
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/**
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* Tests {@link Java3DService}.
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*
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* @author Curtis Rueden
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*/
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public class Java3DServiceTest {
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private Context context;
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private Java3DService j3d;
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private File tmp1;
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private File tmp2;
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@Before
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public void setUp() throws IOException {
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context = new Context(Java3DService.class);
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j3d = context.service(Java3DService.class);
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tmp1 = FileUtils.createTemporaryDirectory("libExt", "1");
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tmp2 = FileUtils.createTemporaryDirectory("libExt", "2");
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}
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@After
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public void tearDown() {
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FileUtils.deleteRecursively(tmp1);
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FileUtils.deleteRecursively(tmp2);
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}
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@Test
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public void testGetLibExtLocations() throws IOException {
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final HashSet<File> expected = new HashSet<File>();
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System.setProperty("java.ext.dirs", tmp1.getAbsolutePath() + ":" +
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tmp2.getAbsolutePath());
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final File j3dcore1 = createFile(tmp1, "j3dcore.jar");
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expected.add(j3dcore1);
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assertEquals(expected, libExtFiles());
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final File j3dcore2 = createFile(tmp2, "j3dcore.jar");
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expected.add(j3dcore2);
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assertEquals(expected, libExtFiles());
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final File vecmath = createFile(tmp1, "vecmath.jar");
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createFile(tmp2, "red-herring");
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expected.add(vecmath);
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assertEquals(expected, libExtFiles());
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System.setProperty("java.ext.dirs", tmp1.getAbsolutePath());
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expected.remove(j3dcore2);
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assertEquals(expected, libExtFiles());
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System.setProperty("java.ext.dirs", "");
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expected.clear();
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assertEquals(expected, libExtFiles());
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System.clearProperty("java.ext.dirs");
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assertEquals(expected, libExtFiles());
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}
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// -- Helper methods --
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private File createFile(final File dir, final String name) throws IOException
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{
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final File file = new File(dir, name);
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file.createNewFile();
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return file;
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}
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private HashSet<File> libExtFiles() {
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return new HashSet<File>(j3d.getLibExtLocations());
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}
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}

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