Use try-with-resources where possible (jenkinsci#6765)

cli/src/main/java/hudson/cli/CLI.java

@@ -491,14 +491,9 @@ synchronized int exit() throws InterruptedException {
 
     private static String computeVersion() {
         Properties props = new Properties();
-        try {
-            InputStream is = CLI.class.getResourceAsStream("/jenkins/cli/jenkins-cli-version.properties");
+        try (InputStream is = CLI.class.getResourceAsStream("/jenkins/cli/jenkins-cli-version.properties")) {
             if (is != null) {
-                try {
-                    props.load(is);
-                } finally {
-                    is.close();
-                }
+                props.load(is);
             }
         } catch (IOException e) {
             e.printStackTrace(); // if the version properties is missing, that's OK.

core/src/main/java/hudson/FilePath.java

@@ -532,13 +532,10 @@ private static class Archive extends MasterToSlaveFileCallable<Integer> {
 
         @Override
             public Integer invoke(File f, VirtualChannel channel) throws IOException {
-                Archiver a = factory.create(out);
-                try {
+                try (Archiver a = factory.create(out)) {
                     scanner.scan(f, ignoringSymlinks(a, verificationRoot, noFollowLinks));
-                } finally {
-                    a.close();
+                    return a.countEntries();
                 }
-                return a.countEntries();
             }
 
             private static final long serialVersionUID = 1L;
@@ -708,10 +705,9 @@ private static void unzip(File dir, InputStream in) throws IOException {
 
     private static void unzip(File dir, File zipFile) throws IOException {
         dir = dir.getAbsoluteFile();    // without absolutization, getParentFile below seems to fail
-        ZipFile zip = new ZipFile(zipFile);
-        Enumeration<ZipEntry> entries = zip.getEntries();
 
-        try {
+        try (ZipFile zip = new ZipFile(zipFile)) {
+            Enumeration<ZipEntry> entries = zip.getEntries();
             while (entries.hasMoreElements()) {
                 ZipEntry e = entries.nextElement();
                 File f = new File(dir, e.getName());
@@ -740,8 +736,6 @@ private static void unzip(File dir, File zipFile) throws IOException {
                     Files.setLastModifiedTime(Util.fileToPath(f), e.getLastModifiedTime());
                 }
             }
-        } finally {
-            zip.close();
         }
     }
 
@@ -922,11 +916,9 @@ public OutputStream compress(OutputStream out) throws IOException {
      * @since 1.292
      */
     public void untarFrom(InputStream _in, final TarCompression compression) throws IOException, InterruptedException {
-        try {
+        try (_in) {
             final InputStream in = new RemoteInputStream(_in, Flag.GREEDY);
             act(new UntarFrom(compression, in));
-        } finally {
-            _in.close();
         }
     }
 
@@ -2947,10 +2939,8 @@ public int tar(OutputStream out, DirScanner scanner) throws IOException, Interru
      */
     private static Integer writeToTar(File baseDir, DirScanner scanner, OutputStream out) throws IOException {
         Archiver tw = ArchiverFactory.TAR.create(out);
-        try {
+        try (tw) {
             scanner.scan(baseDir, tw);
-        } finally {
-            tw.close();
         }
         return tw.countEntries();
     }

core/src/main/java/hudson/TcpSlaveAgentListener.java

@@ -313,7 +313,7 @@ public void run() {
          * Primarily used to test the low-level connectivity.
          */
         private void respondHello(String header, Socket s) throws IOException {
-            try {
+            try (s) {
                 DataOutputStream out = new DataOutputStream(s.getOutputStream());
                 String response;
                 if (header.startsWith("GET / ")) {
@@ -336,8 +336,6 @@ private void respondHello(String header, Socket s) throws IOException {
                 InputStream i = s.getInputStream();
                 IOUtils.copy(i, NullOutputStream.NULL_OUTPUT_STREAM);
                 s.shutdownInput();
-            } finally {
-                s.close();
             }
         }
 
@@ -400,20 +398,18 @@ public String getDisplayName() {
 
         @Override
         public void handle(Socket socket) throws IOException, InterruptedException {
-            try {
+            try (socket) {
                 try (OutputStream stream = socket.getOutputStream()) {
                     LOGGER.log(Level.FINE, "Received ping request from {0}", socket.getRemoteSocketAddress());
                     stream.write(ping);
                     stream.flush();
                     LOGGER.log(Level.FINE, "Sent ping response to {0}", socket.getRemoteSocketAddress());
                 }
-            } finally {
-                socket.close();
             }
         }
 
         public boolean connect(Socket socket) throws IOException {
-            try {
+            try (socket) {
                 LOGGER.log(Level.FINE, "Requesting ping from {0}", socket.getRemoteSocketAddress());
                 try (DataOutputStream out = new DataOutputStream(socket.getOutputStream())) {
                     out.writeUTF("Protocol:Ping");
@@ -435,8 +431,6 @@ public boolean connect(Socket socket) throws IOException {
                         }
                     }
                 }
-            } finally {
-                socket.close();
             }
         }
     }

core/src/main/java/hudson/Util.java

@@ -625,7 +625,7 @@ public static String ensureEndsWith(@CheckForNull String subject, @CheckForNull
      */
     @NonNull
     public static String getDigestOf(@NonNull InputStream source) throws IOException {
-        try {
+        try (source) {
             MessageDigest md5 = getMd5();
             DigestInputStream in = new DigestInputStream(source, md5);
             // Note: IOUtils.copy() buffers the input internally, so there is no
@@ -634,8 +634,6 @@ public static String getDigestOf(@NonNull InputStream source) throws IOException
             return toHexString(md5.digest());
         } catch (NoSuchAlgorithmException e) {
             throw new IOException("MD5 not installed", e);    // impossible
-        } finally {
-            source.close();
         }
         /* JENKINS-18178: confuses Maven 2 runner
         try {

core/src/main/java/hudson/util/io/ArchiverFactory.java

@@ -24,6 +24,7 @@
 
 package hudson.util.io;
 
+import edu.umd.cs.findbugs.annotations.NonNull;
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
 import hudson.FilePath.TarCompression;
 import java.io.IOException;
@@ -42,6 +43,7 @@ public abstract class ArchiverFactory implements Serializable {
     /**
      * Creates an archiver on top of the given stream.
      */
+    @NonNull
     public abstract Archiver create(OutputStream out) throws IOException;
 
     /**
@@ -79,6 +81,7 @@ private TarArchiverFactory(TarCompression method) {
             this.method = method;
         }
 
+        @NonNull
         @Override
         public Archiver create(OutputStream out) throws IOException {
             return new TarArchiver(method.compress(out));
@@ -88,6 +91,7 @@ public Archiver create(OutputStream out) throws IOException {
     }
 
     private static final class ZipArchiverFactory extends ArchiverFactory {
+        @NonNull
         @Override
         public Archiver create(OutputStream out) {
             return new ZipArchiver(out);
@@ -103,6 +107,7 @@ private static final class ZipWithoutSymLinksArchiverFactory extends ArchiverFac
             this.prefix = prefix;
         }
 
+        @NonNull
         @Override
         public Archiver create(OutputStream out) {
             return new ZipArchiver(out, true, prefix);