第8章 その他の Java 8 機能を理解する : 問題 10 : Files.walk メソッド
問題
まず JDK の src.zip ファイルを解凍せよ。
Files.walkメソッドを使用して、予約語
transientvolatile
を含む Java のソースファイルを全て見つけよ。
解答
まず、ソースファイルにキーワードtransientまたはvolatileが含まれるかどうかをチェックするメソッドを用意します。
■ キーワードを含むかどうか?
private boolean hasKeywords(Path path) { try (Scanner scanner = new Scanner(path, "utf-8")) { while (scanner.hasNext()) { String word = scanner.next(); if (word.equals("transient") || word.equals("volatile")) return true; } return false; } catch (IOException ex) { ex.printStackTrace(); throw new RuntimeException(ex); // 後で Stream にかけるのでチェック例外は不可 } }
ワードの抽出は、Scannerのデフォルトに任せます。
Java の言語解析をしてる訳ではないので、コメントに書かれた予約語も拾ってしまいますが、そこはご勘弁を…
では、予約語を含む Java のソースファイルをリストアップしましょう。
Path root = Paths.get("～"); try (Stream<Path> stream = Files.walk(root)) { stream .filter(p -> p.toFile().isFile()) .filter(p -> p.toFile().getName().endsWith(".java")) .filter(p -> hasKeywords(p)) .forEach(System.out::println); } catch (IOException ex) { ex.printStackTrace(); }
■ ファイル一覧（492個）
com/sun/corba/se/impl/activation/RepositoryImpl.java com/sun/corba/se/impl/activation/ServerMain.java com/sun/corba/se/impl/encoding/CachedCodeBase.java com/sun/corba/se/impl/io/FVDCodeBaseImpl.java com/sun/corba/se/impl/io/ObjectStreamClass.java com/sun/corba/se/impl/ior/ObjectReferenceFactoryImpl.java com/sun/corba/se/impl/ior/ObjectReferenceProducerBase.java com/sun/corba/se/impl/ior/ObjectReferenceTemplateImpl.java com/sun/corba/se/impl/naming/cosnaming/NamingContextImpl.java com/sun/corba/se/impl/naming/cosnaming/TransientNameServer.java com/sun/corba/se/impl/naming/cosnaming/TransientNameService.java com/sun/corba/se/impl/naming/pcosnaming/InternalBindingValue.java com/sun/corba/se/impl/naming/pcosnaming/NameServer.java com/sun/corba/se/impl/naming/pcosnaming/NamingContextImpl.java com/sun/corba/se/impl/naming/pcosnaming/ServantManagerImpl.java com/sun/corba/se/impl/oa/toa/TOA.java com/sun/corba/se/impl/oa/toa/TOAImpl.java com/sun/corba/se/impl/orb/ORBDataParserImpl.java com/sun/corba/se/impl/orb/ORBSingleton.java com/sun/corba/se/impl/orbutil/ObjectStreamClassUtil_1_3.java com/sun/corba/se/impl/orbutil/ObjectStreamClass_1_3_1.java com/sun/corba/se/impl/orbutil/threadpool/ThreadPoolImpl.java com/sun/corba/se/impl/presentation/rmi/InvocationHandlerFactoryImpl.java com/sun/corba/se/impl/presentation/rmi/StubInvocationHandlerImpl.java com/sun/corba/se/impl/transport/SelectorImpl.java com/sun/corba/se/impl/util/IdentityHashtable.java com/sun/corba/se/spi/legacy/connection/ORBSocketFactory.java com/sun/corba/se/spi/orb/ORB.java com/sun/corba/se/spi/orb/ORBData.java com/sun/java/swing/plaf/motif/MotifDesktopPaneUI.java com/sun/java/swing/plaf/windows/WindowsLookAndFeel.java com/sun/java/swing/plaf/windows/WindowsToggleButtonUI.java com/sun/javadoc/FieldDoc.java com/sun/jmx/interceptor/DefaultMBeanServerInterceptor.java com/sun/jmx/mbeanserver/JmxMBeanServer.java com/sun/jmx/mbeanserver/Repository.java com/sun/jmx/remote/internal/ClientCommunicatorAdmin.java com/sun/jmx/remote/internal/ClientNotifForwarder.java com/sun/jmx/snmp/agent/SnmpMib.java com/sun/jmx/snmp/agent/SnmpMibAgent.java com/sun/jmx/snmp/agent/SnmpMibTable.java com/sun/jmx/snmp/daemon/CommunicatorServer.java com/sun/jmx/snmp/daemon/SnmpAdaptorServer.java com/sun/jmx/snmp/daemon/SnmpInformRequest.java com/sun/jmx/snmp/daemon/SnmpRequestHandler.java com/sun/jmx/snmp/daemon/SnmpSession.java com/sun/jmx/snmp/daemon/SnmpSocket.java com/sun/jmx/snmp/internal/SnmpEngineImpl.java com/sun/jmx/snmp/SnmpEngine.java com/sun/org/apache/bcel/internal/classfile/JavaClass.java com/sun/org/apache/regexp/internal/RE.java com/sun/org/apache/xalan/internal/utils/SecuritySupport.java com/sun/org/apache/xalan/internal/xsltc/trax/TemplatesImpl.java com/sun/org/apache/xerces/internal/dom/AttrImpl.java com/sun/org/apache/xerces/internal/dom/CharacterDataImpl.java com/sun/org/apache/xerces/internal/dom/ChildNode.java com/sun/org/apache/xerces/internal/dom/CoreDocumentImpl.java com/sun/org/apache/xerces/internal/dom/DeferredAttrImpl.java com/sun/org/apache/xerces/internal/dom/DeferredAttrNSImpl.java com/sun/org/apache/xerces/internal/dom/DeferredCDATASectionImpl.java com/sun/org/apache/xerces/internal/dom/DeferredCommentImpl.java com/sun/org/apache/xerces/internal/dom/DeferredDocumentImpl.java com/sun/org/apache/xerces/internal/dom/DeferredDocumentTypeImpl.java com/sun/org/apache/xerces/internal/dom/DeferredElementDefinitionImpl.java com/sun/org/apache/xerces/internal/dom/DeferredElementImpl.java com/sun/org/apache/xerces/internal/dom/DeferredElementNSImpl.java com/sun/org/apache/xerces/internal/dom/DeferredEntityImpl.java com/sun/org/apache/xerces/internal/dom/DeferredEntityReferenceImpl.java com/sun/org/apache/xerces/internal/dom/DeferredNotationImpl.java com/sun/org/apache/xerces/internal/dom/DeferredProcessingInstructionImpl.java com/sun/org/apache/xerces/internal/dom/DeferredTextImpl.java com/sun/org/apache/xerces/internal/dom/ElementNSImpl.java com/sun/org/apache/xerces/internal/dom/ParentNode.java com/sun/org/apache/xerces/internal/impl/dtd/models/DFAContentModel.java com/sun/org/apache/xerces/internal/impl/dv/xs/AbstractDateTimeDV.java com/sun/org/apache/xerces/internal/impl/XMLStreamReaderImpl.java com/sun/org/apache/xerces/internal/impl/xpath/regex/RegularExpression.java com/sun/org/apache/xerces/internal/impl/xs/models/XSDFACM.java com/sun/org/apache/xerces/internal/impl/xs/XSComplexTypeDecl.java com/sun/org/apache/xerces/internal/util/SymbolTable.java com/sun/org/apache/xerces/internal/utils/SecuritySupport.java com/sun/org/apache/xerces/internal/xni/XMLString.java com/sun/org/apache/xml/internal/dtm/ref/dom2dtm/DOM2DTM.java com/sun/org/apache/xml/internal/dtm/ref/sax2dtm/SAX2DTM.java com/sun/org/apache/xml/internal/security/utils/XMLUtils.java com/sun/org/apache/xml/internal/utils/ThreadControllerWrapper.java com/sun/org/apache/xpath/internal/axes/AxesWalker.java com/sun/org/apache/xpath/internal/axes/ChildTestIterator.java com/sun/org/apache/xpath/internal/axes/DescendantIterator.java com/sun/org/apache/xpath/internal/axes/FilterExprIterator.java com/sun/org/apache/xpath/internal/axes/FilterExprIteratorSimple.java com/sun/org/apache/xpath/internal/axes/FilterExprWalker.java com/sun/org/apache/xpath/internal/axes/LocPathIterator.java com/sun/org/apache/xpath/internal/axes/PredicatedNodeTest.java com/sun/org/apache/xpath/internal/compiler/XPathParser.java com/sun/org/apache/xpath/internal/functions/FuncExtFunctionAvailable.java com/sun/org/apache/xpath/internal/NodeSet.java com/sun/org/apache/xpath/internal/NodeSetDTM.java com/sun/org/apache/xpath/internal/XPath.java com/sun/security/auth/X500Principal.java java/applet/Applet.java java/awt/AWTEvent.java java/awt/Button.java java/awt/Checkbox.java java/awt/CheckboxMenuItem.java java/awt/Choice.java java/awt/color/ColorSpace.java java/awt/color/ICC_ColorSpace.java java/awt/color/ICC_Profile.java java/awt/Component.java java/awt/Container.java java/awt/ContainerOrderFocusTraversalPolicy.java java/awt/Cursor.java java/awt/datatransfer/DataFlavor.java java/awt/Dialog.java java/awt/dnd/DragGestureEvent.java java/awt/dnd/DragGestureRecognizer.java java/awt/dnd/DragSource.java java/awt/dnd/DragSourceContext.java java/awt/dnd/DropTarget.java java/awt/dnd/DropTargetContext.java java/awt/event/FocusEvent.java java/awt/event/InputEvent.java java/awt/event/InputMethodEvent.java java/awt/event/InvocationEvent.java java/awt/event/KeyEvent.java java/awt/event/MouseEvent.java java/awt/event/WindowEvent.java java/awt/Event.java java/awt/EventDispatchThread.java java/awt/EventQueue.java java/awt/font/FontRenderContext.java java/awt/font/NumericShaper.java java/awt/Font.java java/awt/geom/AffineTransform.java java/awt/geom/Path2D.java java/awt/GridBagConstraints.java java/awt/GridBagLayout.java java/awt/ImageCapabilities.java java/awt/KeyboardFocusManager.java java/awt/List.java java/awt/MenuComponent.java java/awt/MenuItem.java java/awt/peer/ComponentPeer.java java/awt/PopupMenu.java java/awt/Robot.java java/awt/Scrollbar.java java/awt/ScrollPaneAdjustable.java java/awt/SystemColor.java java/awt/SystemTray.java java/awt/TextComponent.java java/awt/TextField.java java/awt/Toolkit.java java/awt/TrayIcon.java java/awt/WaitDispatchSupport.java java/awt/Window.java java/beans/beancontext/BeanContextChildSupport.java java/beans/beancontext/BeanContextServicesSupport.java java/beans/beancontext/BeanContextSupport.java java/beans/Beans.java java/beans/ThreadGroupContext.java java/beans/Transient.java java/beans/WeakIdentityMap.java java/io/BufferedInputStream.java java/io/File.java java/io/FileInputStream.java java/io/FileOutputStream.java java/io/FilePermission.java java/io/FilterInputStream.java java/io/ObjectInputStream.java java/io/ObjectOutputStream.java java/io/ObjectStreamClass.java java/io/PipedInputStream.java java/io/RandomAccessFile.java java/lang/Class.java java/lang/ClassValue.java java/lang/invoke/CallSite.java java/lang/invoke/LambdaForm.java java/lang/invoke/MethodHandleImpl.java java/lang/invoke/MutableCallSite.java java/lang/invoke/SwitchPoint.java java/lang/invoke/VolatileCallSite.java java/lang/Package.java java/lang/ref/Finalizer.java java/lang/ref/Reference.java java/lang/ref/ReferenceQueue.java java/lang/reflect/AccessibleObject.java java/lang/reflect/Constructor.java java/lang/reflect/Executable.java java/lang/reflect/Field.java java/lang/reflect/Method.java java/lang/reflect/Modifier.java java/lang/reflect/Parameter.java java/lang/StringBuffer.java java/lang/System.java java/lang/Thread.java java/lang/Throwable.java java/math/BigDecimal.java java/math/BigInteger.java java/net/Inet6Address.java java/net/InetAddress.java java/net/InetSocketAddress.java java/net/SocketPermission.java java/net/URI.java java/net/URL.java java/net/URLPermission.java java/nio/Bits.java java/nio/channels/SelectionKey.java java/nio/channels/spi/AbstractInterruptibleChannel.java java/nio/channels/spi/AbstractSelectionKey.java java/nio/charset/Charset.java java/nio/file/attribute/AclEntry.java java/nio/file/spi/FileSystemProvider.java java/rmi/activation/ActivationID.java java/rmi/server/RemoteObject.java java/security/BasicPermission.java java/security/cert/CertificateRevokedException.java java/security/cert/X509Certificate.java java/security/cert/X509CRL.java java/security/CodeSigner.java java/security/CodeSource.java java/security/KeyFactory.java java/security/KeyPairGenerator.java java/security/KeyStore.java java/security/PermissionCollection.java java/security/Permissions.java java/security/Provider.java java/security/SecureRandom.java java/security/Timestamp.java java/security/UnresolvedPermission.java java/security/UnresolvedPermissionCollection.java java/sql/DriverManager.java java/sql/SQLException.java java/text/DateFormatSymbols.java java/text/DecimalFormat.java java/text/DecimalFormatSymbols.java java/text/MergeCollation.java java/text/RuleBasedCollator.java java/text/SimpleDateFormat.java java/time/chrono/ChronoLocalDateTimeImpl.java java/time/chrono/ChronoZonedDateTimeImpl.java java/time/chrono/HijrahChronology.java java/time/chrono/HijrahDate.java java/time/chrono/JapaneseDate.java java/time/chrono/JapaneseEra.java java/time/chrono/MinguoDate.java java/time/chrono/ThaiBuddhistDate.java java/time/format/DateTimeFormatterBuilder.java java/time/temporal/JulianFields.java java/time/temporal/WeekFields.java java/time/zone/ZoneRules.java java/time/ZoneOffset.java java/time/ZoneRegion.java java/util/AbstractList.java java/util/AbstractMap.java java/util/ArrayDeque.java java/util/ArrayList.java java/util/BitSet.java java/util/Calendar.java java/util/Collections.java java/util/concurrent/ArrayBlockingQueue.java java/util/concurrent/atomic/AtomicBoolean.java java/util/concurrent/atomic/AtomicInteger.java java/util/concurrent/atomic/AtomicIntegerFieldUpdater.java java/util/concurrent/atomic/AtomicLong.java java/util/concurrent/atomic/AtomicLongFieldUpdater.java java/util/concurrent/atomic/AtomicMarkableReference.java java/util/concurrent/atomic/AtomicReference.java java/util/concurrent/atomic/AtomicReferenceFieldUpdater.java java/util/concurrent/atomic/AtomicStampedReference.java java/util/concurrent/atomic/Striped64.java java/util/concurrent/CompletableFuture.java java/util/concurrent/ConcurrentHashMap.java java/util/concurrent/ConcurrentLinkedDeque.java java/util/concurrent/ConcurrentLinkedQueue.java java/util/concurrent/ConcurrentSkipListMap.java java/util/concurrent/CopyOnWriteArrayList.java java/util/concurrent/CountedCompleter.java java/util/concurrent/DelayQueue.java java/util/concurrent/Exchanger.java java/util/concurrent/ExecutorCompletionService.java java/util/concurrent/ForkJoinPool.java java/util/concurrent/ForkJoinTask.java java/util/concurrent/FutureTask.java java/util/concurrent/LinkedBlockingDeque.java java/util/concurrent/LinkedBlockingQueue.java java/util/concurrent/LinkedTransferQueue.java java/util/concurrent/locks/AbstractOwnableSynchronizer.java java/util/concurrent/locks/AbstractQueuedLongSynchronizer.java java/util/concurrent/locks/AbstractQueuedSynchronizer.java java/util/concurrent/locks/ReentrantReadWriteLock.java java/util/concurrent/locks/StampedLock.java java/util/concurrent/Phaser.java java/util/concurrent/PriorityBlockingQueue.java java/util/concurrent/ScheduledThreadPoolExecutor.java java/util/concurrent/SynchronousQueue.java java/util/concurrent/ThreadLocalRandom.java java/util/concurrent/ThreadPoolExecutor.java java/util/Currency.java java/util/Date.java java/util/EnumMap.java java/util/EventObject.java java/util/GregorianCalendar.java java/util/HashMap.java java/util/HashSet.java java/util/Hashtable.java java/util/IdentityHashMap.java java/util/JapaneseImperialCalendar.java java/util/jar/JarFile.java java/util/jar/JarVerifier.java java/util/LinkedHashMap.java java/util/LinkedList.java java/util/Locale.java java/util/logging/Handler.java java/util/logging/Level.java java/util/logging/Logger.java java/util/logging/LogManager.java java/util/logging/LogRecord.java java/util/logging/MemoryHandler.java java/util/logging/StreamHandler.java java/util/PriorityQueue.java java/util/PropertyPermission.java java/util/regex/Pattern.java java/util/ResourceBundle.java java/util/Scanner.java java/util/SimpleTimeZone.java java/util/stream/AbstractShortCircuitTask.java java/util/stream/SliceOps.java java/util/TimeZone.java java/util/TreeMap.java java/util/TreeSet.java java/util/WeakHashMap.java java/util/zip/ZipFile.java javax/accessibility/AccessibleContext.java javax/accessibility/AccessibleState.java javax/lang/model/element/UnknownAnnotationValueException.java javax/lang/model/element/UnknownElementException.java javax/lang/model/type/MirroredTypeException.java javax/lang/model/type/MirroredTypesException.java javax/lang/model/type/UnknownTypeException.java javax/management/AttributeList.java javax/management/ImmutableDescriptor.java javax/management/loading/MLet.java javax/management/MBeanConstructorInfo.java javax/management/MBeanFeatureInfo.java javax/management/MBeanInfo.java javax/management/MBeanNotificationInfo.java javax/management/MBeanOperationInfo.java javax/management/MBeanPermission.java javax/management/MBeanServerPermission.java javax/management/modelmbean/DescriptorSupport.java javax/management/modelmbean/RequiredModelMBean.java javax/management/monitor/Monitor.java javax/management/ObjectName.java javax/management/openmbean/ArrayType.java javax/management/openmbean/CompositeType.java javax/management/openmbean/OpenMBeanAttributeInfoSupport.java javax/management/openmbean/OpenMBeanConstructorInfoSupport.java javax/management/openmbean/OpenMBeanInfoSupport.java javax/management/openmbean/OpenMBeanOperationInfoSupport.java javax/management/openmbean/OpenMBeanParameterInfoSupport.java javax/management/openmbean/OpenType.java javax/management/openmbean/SimpleType.java javax/management/openmbean/TabularDataSupport.java javax/management/openmbean/TabularType.java javax/management/relation/RoleList.java javax/management/relation/RoleUnresolvedList.java javax/management/remote/JMXServiceURL.java javax/management/remote/rmi/RMIConnector.java javax/management/StandardMBean.java javax/management/timer/Timer.java javax/naming/CompositeName.java javax/naming/CompoundName.java javax/naming/directory/BasicAttribute.java javax/naming/directory/BasicAttributes.java javax/naming/ldap/LdapName.java javax/naming/ldap/Rdn.java javax/print/attribute/HashAttributeSet.java javax/print/DocFlavor.java javax/print/event/PrintJobEvent.java javax/print/MimeType.java javax/rmi/CORBA/Stub.java javax/security/auth/kerberos/DelegationPermission.java javax/security/auth/kerberos/KerberosKey.java javax/security/auth/kerberos/KerberosPrincipal.java javax/security/auth/kerberos/KerberosTicket.java javax/security/auth/kerberos/KeyImpl.java javax/security/auth/kerberos/ServicePermission.java javax/security/auth/PrivateCredentialPermission.java javax/security/auth/Subject.java javax/security/auth/x500/X500Principal.java javax/sql/rowset/BaseRowSet.java javax/sql/rowset/serial/SerialJavaObject.java javax/sql/rowset/spi/SyncFactory.java javax/swing/AbstractAction.java javax/swing/AbstractButton.java javax/swing/AbstractCellEditor.java javax/swing/AbstractSpinnerModel.java javax/swing/ActionMap.java javax/swing/ActionPropertyChangeListener.java javax/swing/AncestorNotifier.java javax/swing/BoxLayout.java javax/swing/colorchooser/DefaultColorSelectionModel.java javax/swing/DefaultBoundedRangeModel.java javax/swing/DefaultButtonModel.java javax/swing/DefaultDesktopManager.java javax/swing/DefaultSingleSelectionModel.java javax/swing/event/EventListenerList.java javax/swing/ImageIcon.java javax/swing/InputMap.java javax/swing/JComponent.java javax/swing/JDesktopPane.java javax/swing/JFileChooser.java javax/swing/JLayer.java javax/swing/JList.java javax/swing/JMenuBar.java javax/swing/JOptionPane.java javax/swing/JPopupMenu.java javax/swing/JProgressBar.java javax/swing/JSlider.java javax/swing/JSpinner.java javax/swing/JTabbedPane.java javax/swing/JTable.java javax/swing/JTree.java javax/swing/JViewport.java javax/swing/LegacyGlueFocusTraversalPolicy.java javax/swing/MenuSelectionManager.java javax/swing/plaf/basic/BasicLookAndFeel.java javax/swing/plaf/basic/BasicPopupMenuUI.java javax/swing/plaf/basic/BasicScrollBarUI.java javax/swing/plaf/basic/BasicSliderUI.java javax/swing/plaf/basic/BasicTabbedPaneUI.java javax/swing/plaf/basic/BasicTextUI.java javax/swing/plaf/basic/BasicTreeUI.java javax/swing/plaf/basic/LazyActionMap.java javax/swing/plaf/metal/MetalBumps.java javax/swing/plaf/metal/MetalIconFactory.java javax/swing/plaf/nimbus/AbstractRegionPainter.java javax/swing/plaf/synth/SynthContext.java javax/swing/plaf/synth/SynthSliderUI.java javax/swing/Popup.java javax/swing/PopupFactory.java javax/swing/RepaintManager.java javax/swing/SortingFocusTraversalPolicy.java javax/swing/SwingWorker.java javax/swing/table/DefaultTableColumnModel.java javax/swing/table/JTableHeader.java javax/swing/table/TableColumn.java javax/swing/text/AbstractDocument.java javax/swing/text/DefaultCaret.java javax/swing/text/DefaultFormatter.java javax/swing/text/DefaultStyledDocument.java javax/swing/text/GapContent.java javax/swing/text/html/CSS.java javax/swing/text/html/HTMLEditorKit.java javax/swing/text/InternationalFormatter.java javax/swing/text/JTextComponent.java javax/swing/text/MaskFormatter.java javax/swing/text/PlainDocument.java javax/swing/text/SimpleAttributeSet.java javax/swing/text/StringContent.java javax/swing/text/StyleContext.java javax/swing/Timer.java javax/swing/TimerQueue.java javax/swing/ToolTipManager.java javax/swing/tree/DefaultMutableTreeNode.java javax/swing/tree/DefaultTreeCellEditor.java javax/swing/tree/DefaultTreeCellRenderer.java javax/swing/tree/DefaultTreeSelectionModel.java javax/xml/bind/annotation/XmlAccessType.java javax/xml/bind/annotation/XmlAnyAttribute.java javax/xml/bind/annotation/XmlElement.java javax/xml/bind/annotation/XmlElements.java javax/xml/bind/annotation/XmlElementWrapper.java javax/xml/bind/annotation/XmlID.java javax/xml/bind/annotation/XmlIDREF.java javax/xml/bind/annotation/XmlType.java javax/xml/bind/annotation/XmlValue.java javax/xml/bind/DatatypeConverter.java javax/xml/bind/JAXB.java javax/xml/bind/JAXBException.java javax/xml/bind/TypeConstraintException.java javax/xml/datatype/FactoryFinder.java javax/xml/parsers/FactoryFinder.java javax/xml/stream/FactoryFinder.java javax/xml/stream/XMLStreamReader.java javax/xml/transform/FactoryFinder.java javax/xml/validation/SchemaFactoryFinder.java javax/xml/xpath/XPathFactoryFinder.java org/omg/CORBA/portable/ObjectImpl.java org/omg/PortableServer/POAOperations.java org/omg/PortableServer/Servant.java
