Some Small Code Improvements

I focused on low-hanging fruits that my IDE proposed while making sure, not to change behavior or potentially breaking any API usage. The changes include but are not limited to:
- replacing lambdas with method references
- Simplifying conditions
- Using methods from the JDK over custom ones.
- Removing No-Ops

Author: BrandonSchmitt

dbus-java-core/src/main/java/org/freedesktop/dbus/RemoteInvocationHandler.java

@@ -30,8 +30,8 @@ public class RemoteInvocationHandler implements InvocationHandler {
     private static final Logger LOGGER = LoggerFactory.getLogger(RemoteInvocationHandler.class);
 
     // CHECKSTYLE:OFF
-    AbstractConnection conn;
-    RemoteObject       remote;
+    private final AbstractConnection conn;
+    private final RemoteObject       remote;
     // CHECKSTYLE:ON
 
     public RemoteInvocationHandler(AbstractConnection _conn, RemoteObject _remote) {

dbus-java-core/src/main/java/org/freedesktop/dbus/StructHelper.java

@@ -109,7 +109,7 @@ public static <T extends Struct> void convertToStructCollection(Collection<Objec
             if (constructorArgClasses.length != object.length) {
                 throw new IllegalArgumentException("Struct length does not match argument length");
             }
-            T x = createStruct(constructorArgClasses, (Object) object, _structType);
+            T x = createStruct(constructorArgClasses, object, _structType);
             _result.add(x);
         }
 

dbus-java-core/src/main/java/org/freedesktop/dbus/connections/BusAddress.java

@@ -49,7 +49,7 @@ public static BusAddress of(String _address) {
             throw new InvalidBusAddressException("Bus address is blank");
         }
 
-        BusAddress busAddress = new BusAddress((BusAddress) null);
+        BusAddress busAddress = new BusAddress(null);
 
         LOGGER.trace("Parsing bus address: {}", _address);
 

dbus-java-core/src/main/java/org/freedesktop/dbus/connections/SASL.java

@@ -20,7 +20,6 @@
 import java.io.*;
 import java.net.SocketException;
 import java.nio.ByteBuffer;
-import java.nio.channels.NetworkChannel;
 import java.nio.channels.SocketChannel;
 import java.nio.charset.Charset;
 import java.nio.file.Files;
@@ -600,14 +599,14 @@ public boolean auth(SocketChannel _sock, AbstractTransport _transport) throws IO
                 switch (state) {
                     case INITIAL_STATE:
                         ByteBuffer buf = ByteBuffer.allocate(1);
-                        if (_sock instanceof NetworkChannel) {
+                        if (_sock != null) {
                             _sock.read(buf); // 0
                             state = SaslAuthState.WAIT_AUTH;
                         } else {
                             try {
                                 int kuid = -1;
                                 if (_transport instanceof AbstractUnixTransport aut) {
-                                    kuid = aut.getUid(_sock);
+                                    kuid = aut.getUid(null);
                                 }
                                 if (kuid >= 0) {
                                     kernelUid = stupidlyEncode("" + kuid);

dbus-java-core/src/main/java/org/freedesktop/dbus/connections/base/DBusBoundPropertyHandler.java

@@ -28,7 +28,6 @@
 import java.util.*;
 import java.util.Map.Entry;
 import java.util.concurrent.atomic.AtomicBoolean;
-import java.util.stream.Collectors;
 
 /**
  * Abstract class containing methods for handling DBus properties and {@link DBusBoundProperty} annotation. <br>
@@ -125,9 +124,9 @@ protected PropHandled handleGetAll(ExportedObject _exportObject, final MethodCal
                             Object val = invokeMethod(_methodCall, propMeth, object);
 
                             // when the value is a collection, array or map, wrap them in a proper variant type
-                            if (val != null && val.getClass().isArray() || Collection.class.isInstance(val) || Map.class.isInstance(val)) {
+                            if (val != null && val.getClass().isArray() || val instanceof Collection || val instanceof Map) {
                                 String[] dataType = Marshalling.getDBusType(propEn.getValue().getGenericReturnType());
-                                String dataTypeStr = Arrays.stream(dataType).collect(Collectors.joining());
+                                String dataTypeStr = String.join("", dataType);
                                 getLogger().trace("Creating embedded Array/Collection/Map of type {}", dataTypeStr);
                                 val = new Variant<>(val, dataTypeStr);
                             }

dbus-java-core/src/main/java/org/freedesktop/dbus/connections/base/FallbackContainer.java

@@ -30,7 +30,6 @@ public synchronized void remove(String _path) {
     }
 
     public synchronized ExportedObject get(String _path) {
-        int best = 0;
         ExportedObject bestobject = null;
         String[] pathel = _path.split("/");
         for (Map.Entry<String[], ExportedObject> entry : fallbacks.entrySet()) {
@@ -48,7 +47,7 @@ public synchronized ExportedObject get(String _path) {
                     break;
                 }
             }
-            if (i > 0 && i == fbpath.length && i > best) {
+            if (i > 0 && i == fbpath.length) {
                 bestobject = entry.getValue();
             }
             logger.trace("Matches {} bestobject now {}", i, bestobject);

dbus-java-core/src/main/java/org/freedesktop/dbus/connections/base/IncomingMessageThread.java

@@ -32,14 +32,11 @@ public void terminate() {
     @Override
     public void run() {
 
-        Message msg;
         while (!terminate) {
-            msg = null;
-
             // read from the wire
             try {
                 // this blocks on outgoing being non-empty or a message being available.
-                msg = connection.readIncoming();
+                Message msg = connection.readIncoming();
                 if (msg != null) {
                     logger.trace("Read message from {}: {}", connection.getTransport(), msg);
 

dbus-java-core/src/main/java/org/freedesktop/dbus/connections/impl/DBusConnection.java

@@ -132,15 +132,11 @@ public void register() throws DBusException {
     }
 
     /**
-     * Do some action with the currently registered names in a synchronized manor.
+     * Do some action with the currently registered names in a synchronized manner.
      *
-     * @param _exClz exception type which may be thrown
      * @param _action action to execute
-     * @param <X> type of exception
      *
      * @return whatever the action returns
-     *
-     * @throws X thrown when action throws
      */
     private <T> T doWithBusNamesAndReturn(Function<List<String>, T> _action) {
         if (_action == null) {
@@ -152,13 +148,9 @@ private <T> T doWithBusNamesAndReturn(Function<List<String>, T> _action) {
     }
 
     /**
-     * Do some action with the currently registered names in a synchronized manor.
+     * Do some action with the currently registered names in a synchronized manner.
      *
-     * @param _exClz exception type which may be thrown
      * @param _action action to execute
-     * @param <X> type of exception
-     *
-     * @throws X thrown when action throws
      */
     private void doWithBusNames(Consumer<List<String>> _action) {
         doWithBusNamesAndReturn(bn -> {
@@ -302,7 +294,7 @@ public void requestBusName(String _busname) throws DBusException {
      * @return unique name
      */
     public String getUniqueName() {
-        return doWithBusNamesAndReturn(bn -> bn.getFirst());
+        return doWithBusNamesAndReturn(List::getFirst);
     }
 
     /**
@@ -311,11 +303,7 @@ public String getUniqueName() {
      * @return connection names
      */
     public String[] getNames() {
-        return doWithBusNamesAndReturn(bn -> {
-            Set<String> names = new TreeSet<>();
-            names.addAll(bn);
-            return names;
-        }).toArray(String[]::new);
+        return doWithBusNamesAndReturn(TreeSet::new).toArray(String[]::new);
     }
 
     @Override
@@ -514,7 +502,7 @@ public <T extends DBusSignal> AutoCloseable addSigHandler(DBusMatchRule _rule, D
             try {
                 dbus.AddMatch(_rule.toString());
             } catch (DBusExecutionException _ex) {
-                logger.debug("Cannot add match rule: " + _rule.toString(), _ex);
+                logger.debug("Cannot add match rule: {}", _rule, _ex);
                 throw new DBusException("Cannot add match rule.", _ex);
             }
         }

dbus-java-core/src/main/java/org/freedesktop/dbus/connections/impl/DBusConnectionBuilder.java

@@ -121,23 +121,21 @@ private static BusAddress validateTransportAddress(BusAddress _address) {
             throw new IllegalArgumentException("No transports found to connect to DBus. Please add at least one transport provider to your classpath");
         }
 
-        BusAddress address = _address;
-
         // no unix transport but address wants to use a unix socket
         if (!TransportBuilder.getRegisteredBusTypes().contains("UNIX")
-                && address != null
-                && address.isBusType("UNIX")) {
+                && _address != null
+                && _address.isBusType("UNIX")) {
             throw new AddressResolvingException("No transports found to handle UNIX socket connections. Please add a unix-socket transport provider to your classpath");
         }
 
         // no tcp transport but TCP address given
         if (!TransportBuilder.getRegisteredBusTypes().contains("TCP")
-                && address != null
-                && address.isBusType("TCP")) {
+                && _address != null
+                && _address.isBusType("TCP")) {
             throw new AddressResolvingException("No transports found to handle TCP connections. Please add a TCP transport provider to your classpath");
         }
 
-        return address;
+        return _address;
 
     }
 

dbus-java-core/src/main/java/org/freedesktop/dbus/connections/impl/IRemoteObjectGetter.java

@@ -64,7 +64,7 @@ default <I extends DBusInterface> I getPeerRemoteObject(String _busname, DBusPat
      * happens, try specifying the interface explicitly.
      *
      * @param _busname
-     *            The bus name to connect to. Usually a well known bus name name in dot-notation (such as
+     *            The bus name to connect to. Usually a well known bus name in dot-notation (such as
      *            "org.freedesktop.local") or may be a DBus address such as ":1-16".
      * @param _objectpath
      *            The path on which the process is exporting the object.