Use try-with-resources where possible

and make StanzaCollector implement AutoCloseable.

smack-core/src/main/java/org/jivesoftware/smack/StanzaCollector.java

@@ -41,7 +41,7 @@ import org.jivesoftware.smack.packet.Stanza;
  * @see XMPPConnection#createStanzaCollector(StanzaFilter)
  * @author Matt Tucker
  */
-public class StanzaCollector {
+public class StanzaCollector implements AutoCloseable {
 
     private final StanzaFilter packetFilter;
 
@@ -92,6 +92,10 @@ public class StanzaCollector {
         cancelled = true;
         connection.removeStanzaCollector(this);
         notifyAll();
+
+        if (collectorToReset != null) {
+            collectorToReset.cancel();
+        }
     }
 
     /**
@@ -431,4 +435,9 @@ public class StanzaCollector {
         }
     }
 
+    @Override
+    public void close() {
+        cancel();
+    }
+
 }

smack-core/src/main/java/org/jivesoftware/smack/provider/ProviderFileLoader.java

@@ -26,7 +26,6 @@ import java.util.logging.Logger;
 
 import org.jivesoftware.smack.packet.ExtensionElement;
 import org.jivesoftware.smack.packet.IQ;
-import org.jivesoftware.smack.util.CloseableUtil;
 
 import org.xmlpull.v1.XmlPullParser;
 import org.xmlpull.v1.XmlPullParserFactory;
@@ -54,10 +53,10 @@ public class ProviderFileLoader implements ProviderLoader {
     @SuppressWarnings("unchecked")
     public ProviderFileLoader(InputStream providerStream, ClassLoader classLoader) {
         // Load processing providers.
-        try {
+        try (InputStream is = providerStream) {
             XmlPullParser parser = XmlPullParserFactory.newInstance().newPullParser();
             parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, true);
-            parser.setInput(providerStream, "UTF-8");
+            parser.setInput(is, "UTF-8");
             int eventType = parser.getEventType();
             do {
                 if (eventType == XmlPullParser.START_TAG) {
@@ -141,9 +140,6 @@ public class ProviderFileLoader implements ProviderLoader {
             LOGGER.log(Level.SEVERE, "Unknown error occurred while parsing provider file", e);
             exceptions.add(e);
         }
-        finally {
-            CloseableUtil.maybeClose(providerStream, LOGGER);
-        }
     }
 
     @Override

smack-core/src/main/java/org/jivesoftware/smack/util/FileUtils.java

@@ -113,9 +113,7 @@ public final class FileUtils {
      */
     @SuppressWarnings("DefaultCharset")
     public static String readFileOrThrow(File file) throws IOException {
-        Reader reader = null;
+        try (Reader reader = new FileReader(file)) {
-        try {
-            reader = new FileReader(file);
             char[] buf = new char[8192];
             int len;
             StringBuilder s = new StringBuilder();
@@ -124,11 +122,6 @@ public final class FileUtils {
             }
             return s.toString();
         }
-        finally {
-            if (reader != null) {
-                reader.close();
-            }
-        }
     }
 
     public static String readFile(File file) {

smack-experimental/src/main/java/org/jivesoftware/smackx/iot/data/IoTDataManager.java

@@ -192,9 +192,9 @@ public final class IoTDataManager extends IoTManager {
             doneCollector.nextResult();
         }
         finally {
-            // Ensure that the two collectors are canceled in any case.
+            // Canceling dataCollector will also cancel the doneCollector since it is configured as dataCollector's
+            // collector to reset.
             dataCollector.cancel();
-            doneCollector.cancel();
         }
 
         int collectedCount = dataCollector.getCollectedCount();

smack-experimental/src/main/java/org/jivesoftware/smackx/mam/MamManager.java

@@ -546,17 +546,15 @@ public final class MamManager extends Manager {
 
         StanzaCollector.Configuration resultCollectorConfiguration = StanzaCollector.newConfiguration()
                 .setStanzaFilter(new MamResultFilter(mamQueryIq)).setCollectorToReset(mamFinIQCollector);
-        StanzaCollector resultCollector = connection.createStanzaCollector(resultCollectorConfiguration);
 
-        try {
+        StanzaCollector cancelledResultCollector;
+        try (StanzaCollector resultCollector = connection.createStanzaCollector(resultCollectorConfiguration)) {
             connection.sendStanza(mamQueryIq);
             mamFinIQ = mamFinIQCollector.nextResultOrThrow();
-        } finally {
+            cancelledResultCollector = resultCollector;
-            mamFinIQCollector.cancel();
-            resultCollector.cancel();
         }
 
-        return new MamQueryPage(resultCollector, mamFinIQ);
+        return new MamQueryPage(cancelledResultCollector, mamFinIQ);
     }
 
     /**

smack-extensions/src/main/java/org/jivesoftware/smackx/caps/cache/SimpleDirectoryPersistentCache.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright © 2011-2018 Florian Schmaus
+ * Copyright © 2011-2019 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -130,11 +130,8 @@ public class SimpleDirectoryPersistentCache implements EntityCapsPersistentCache
      * @throws IOException
      */
     private static void writeInfoToFile(File file, DiscoverInfo info) throws IOException {
-        DataOutputStream dos = new DataOutputStream(new FileOutputStream(file));
+        try (DataOutputStream dos = new DataOutputStream(new FileOutputStream(file))) {
-        try {
             dos.writeUTF(info.toXML(null).toString());
-        } finally {
-            dos.close();
         }
     }
 
@@ -146,12 +143,9 @@ public class SimpleDirectoryPersistentCache implements EntityCapsPersistentCache
      * @throws Exception
      */
     private static DiscoverInfo restoreInfoFromFile(File file) throws Exception {
-        DataInputStream dis = new DataInputStream(new FileInputStream(file));
         String fileContent;
-        try {
+        try (DataInputStream dis = new DataInputStream(new FileInputStream(file))) {
             fileContent = dis.readUTF();
-        } finally {
-            dis.close();
         }
         if (fileContent == null) {
             return null;

smack-extensions/src/main/java/org/jivesoftware/smackx/jiveproperties/packet/JivePropertiesExtension.java

@@ -29,7 +29,6 @@ import java.util.logging.Logger;
 
 import org.jivesoftware.smack.packet.ExtensionElement;
 import org.jivesoftware.smack.packet.Message;
-import org.jivesoftware.smack.util.CloseableUtil;
 import org.jivesoftware.smack.util.XmlStringBuilder;
 import org.jivesoftware.smack.util.stringencoder.Base64;
 
@@ -177,11 +176,10 @@ public class JivePropertiesExtension implements ExtensionElement {
             // a binary format, which won't work well inside of XML. Therefore, we base-64
             // encode the binary data before adding it.
             else {
-                ByteArrayOutputStream byteStream = null;
+                try (
-                ObjectOutputStream out = null;
+                    ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
-                try {
+                    ObjectOutputStream out = new ObjectOutputStream(byteStream);
-                    byteStream = new ByteArrayOutputStream();
+                    ) {
-                    out = new ObjectOutputStream(byteStream);
                     out.writeObject(value);
                     type = "java-object";
                     valueStr = Base64.encodeToString(byteStream.toByteArray());
@@ -191,10 +189,6 @@ public class JivePropertiesExtension implements ExtensionElement {
                     type = "java-object";
                     valueStr = "Serializing error: " + e.getMessage();
                 }
-                finally {
-                    CloseableUtil.maybeClose(out, LOGGER);
-                    CloseableUtil.maybeClose(byteStream, LOGGER);
-                }
             }
             xml.attribute("type", type);
             xml.rightAngleBracket();

smack-extensions/src/main/java/org/jivesoftware/smackx/offline/OfflineMessageManager.java

@@ -165,8 +165,7 @@ public class OfflineMessageManager {
             }
         });
         int pendingNodes = nodes.size();
-        StanzaCollector messageCollector = connection.createStanzaCollector(messageFilter);
+        try (StanzaCollector messageCollector = connection.createStanzaCollector(messageFilter)) {
-        try {
             connection.createStanzaCollectorAndSend(request).nextResultOrThrow();
             // Collect the received offline messages
             Message message;
@@ -181,10 +180,6 @@ public class OfflineMessageManager {
                 }
             } while (message != null && pendingNodes > 0);
         }
-        finally {
-            // Stop queuing offline messages
-            messageCollector.cancel();
-        }
         return messages;
     }
 
@@ -206,10 +201,9 @@ public class OfflineMessageManager {
 
         StanzaCollector resultCollector = connection.createStanzaCollectorAndSend(request);
         StanzaCollector.Configuration messageCollectorConfiguration = StanzaCollector.newConfiguration().setStanzaFilter(PACKET_FILTER).setCollectorToReset(resultCollector);
-        StanzaCollector messageCollector = connection.createStanzaCollector(messageCollectorConfiguration);
 
         List<Message> messages;
-        try {
+        try (StanzaCollector messageCollector = connection.createStanzaCollector(messageCollectorConfiguration)) {
             resultCollector.nextResultOrThrow();
             // Be extra safe, cancel the message collector right here so that it does not collector
             // other messages that eventually match (although I've no idea how this could happen in
@@ -221,11 +215,6 @@ public class OfflineMessageManager {
                 messages.add(message);
             }
         }
-        finally {
-            // Ensure that the message collector is canceled even if nextResultOrThrow threw. It
-            // doesn't matter if we cancel the message collector twice
-            messageCollector.cancel();
-        }
         return messages;
     }
 

smack-extensions/src/main/java/org/jivesoftware/smackx/vcardtemp/packet/VCard.java

@@ -491,9 +491,7 @@ public final class VCard extends IQ {
     }
 
     private static byte[] getFileBytes(File file) throws IOException {
-        BufferedInputStream bis = null;
+        try (BufferedInputStream bis = new BufferedInputStream(new FileInputStream(file))) {
-        try {
-            bis = new BufferedInputStream(new FileInputStream(file));
             int bytes = (int) file.length();
             byte[] buffer = new byte[bytes];
             int readBytes = bis.read(buffer);
@@ -502,11 +500,6 @@ public final class VCard extends IQ {
             }
             return buffer;
         }
-        finally {
-            if (bis != null) {
-                bis.close();
-            }
-        }
     }
 
     /**

smack-integration-test/src/main/java/org/igniterealtime/smack/inttest/AbstractSmackIntTest.java

@@ -55,15 +55,10 @@ public abstract class AbstractSmackIntTest {
                     throws NoResponseException, XMPPErrorException, NotConnectedException, InterruptedException {
         StanzaCollector.Configuration configuration = StanzaCollector.newConfiguration().setStanzaFilter(
                         filter).setSize(1);
-        StanzaCollector collector = connection.createStanzaCollector(configuration);
+        try (StanzaCollector collector = connection.createStanzaCollector(configuration)) {
-
-        try {
             action.run();
             collector.nextResultOrThrow(timeout);
         }
-        finally {
-            collector.cancel();
-        }
     }
 
     @SuppressWarnings("ThreadPriorityCheck")