内部类

 

       匿名内部类，比如下面函数内部initialize定义了两个匿名类（红色代码部分）：

   publicsynchronizedvoid initialize(Environment env,

                                        Detector detector,

                                        DaemonListener listener,

                                        PlainLogger[] loggers) throws NullPointerException,

                    IllegalStateException {

 

        if (fInitialized) {

            return;

        }

 

        Helper.notNull( env, "environment" );

        Helper.notNull( detector, "detector" );

 

       fDetector = detector;

        fDaemonListener = listener;

 

        // Check the loggers.

        if (loggers != null) {

            for (int i = 0; i < loggers.length; i++) {

                if (loggers[i] != null && !loggers[i].isLoggable( )) {

                    thrownew IllegalStateException( "Logger" + i

                                                     + " isn't loggable" );

                }

            }

 

            // Get loggers.

            if (loggers.length >= 1) {

                fAppLogger = loggers[0];

            }

            if (loggers.length >= 2) {

                fErrorLogger = loggers[1];

            }

        }

 

        // Initialize the daemon options first.

        initDaemonOptions( env );

 

        // Check the loggers.

        if (loggers != null) {

            for (int i = 0; i < loggers.length; i++) {

                if (loggers[i] != null && !loggers[i].isLoggable( )) {

                    thrownew IllegalStateException( "Logger" + i

                                                     + " isn't loggable" );

                }

            }

 

            // Get loggers.

            if (loggers.length >= 1) {

                fAppLogger = loggers[0];

            }

            if (loggers.length >= 2) {

                fErrorLogger = loggers[1];

            }

        }

 

        log( "Using Rv Daemon: " + fDaemonOptions.getCurTransportOption( ) );

 

        // Implements a detector listener.

        DetectorListener detectorListener = new DetectorListener( ) {

 

            public void onConnected() {

                String newDaemon = fDaemonOptions.getCurTransportOption( );

                log( "Connected to Daemon: " + newDaemon );

                synchronized (Daemon.this) {

                    fState = DaemonState.CONNECTED;

                   

                    for (Iterator i = fSwitchHandlers.iterator( ); i.hasNext( );) {

                        ((SwitchHandler) i.next( )).doSwitching( newDaemon );

                    }

                   

                    fState = DaemonState.SWITCHED;

                }

 

                log( "Switched to Daemon: " + newDaemon );

 

                if (fDaemonListener != null) {

                    fDaemonListener.onStateChanged( fState,

                                                    fLastDaemon,

                                                    newDaemon );

                }

            }

 

            public void onDisconnected() {

 

                synchronized (Daemon.this) {

                    fState = DaemonState.SWITCHING;

                    round( );

                }

                log( "Disconnected to Daemon: " + fLastDaemon );

 

                if (fDaemonListener != null) {

                    fDaemonListener.onStateChanged( fState,

                                                    fLastDaemon,

                                                    fDaemonOptions.peekNextAvailTransportOption( ) );

                }

                detect( );

            }

        };

 

        fDetector.registerDetectorListener( detectorListener );

 

        // Do the first connecting in other thread.

        Thread first = new Thread( "InitialDetector" ) {

            public void run() {

                detect( );

            }

        };

        first.start( );

 

        fInitialized = true;

        log( "Daemon detecting initialized." );

    }

      

       new DetectorListener( ){...}等价于创建一个派生自接口DectorListener的子类，然后返回该类的引用。 同样的道理，另外一个是从Thread派生并且重写了run函数，因此该类可以作为一个县城对象运行。