diff --git a/core/src/main/java/hudson/PluginManager.java b/core/src/main/java/hudson/PluginManager.java
index ba0648b7bc..d11b84990c 100644
--- a/core/src/main/java/hudson/PluginManager.java
+++ b/core/src/main/java/hudson/PluginManager.java
@@ -1770,12 +1770,9 @@ public abstract class PluginManager extends AbstractModelObject implements OnMas
 
     protected String identifyPluginShortName(File t) {
         try {
-            JarFile j = new JarFile(t);
-            try {
+            try (JarFile j = new JarFile(t)) {
                 String name = j.getManifest().getMainAttributes().getValue("Short-Name");
-                if (name!=null) return name;
-            } finally {
-                j.close();
+                if (name != null) return name;
             }
         } catch (IOException e) {
             LOGGER.log(WARNING, "Failed to identify the short name from "+t,e);
diff --git a/core/src/main/java/hudson/console/ConsoleNote.java b/core/src/main/java/hudson/console/ConsoleNote.java
index 3c18b65716..1dec066e56 100644
--- a/core/src/main/java/hudson/console/ConsoleNote.java
+++ b/core/src/main/java/hudson/console/ConsoleNote.java
@@ -192,18 +192,15 @@ public abstract class ConsoleNote<T> implements Serializable, Describable<Consol
 
         ByteArrayOutputStream buf2 = new ByteArrayOutputStream();
 
-        DataOutputStream dos = new DataOutputStream(new Base64OutputStream(buf2,true,-1,null));
-        try {
+        try (DataOutputStream dos = new DataOutputStream(new Base64OutputStream(buf2, true, -1, null))) {
             buf2.write(PREAMBLE);
             if (JenkinsJVM.isJenkinsJVM()) { // else we are in another JVM and cannot sign; result will be ignored unless INSECURE
                 byte[] mac = MAC.mac(buf.toByteArray());
-                dos.writeInt(- mac.length); // negative to differentiate from older form
+                dos.writeInt(-mac.length); // negative to differentiate from older form
                 dos.write(mac);
             }
             dos.writeInt(buf.size());
             buf.writeTo(dos);
-        } finally {
-            dos.close();
         }
         buf2.write(POSTAMBLE);
         return buf2;
diff --git a/core/src/main/java/hudson/tasks/Maven.java b/core/src/main/java/hudson/tasks/Maven.java
index 63c3d944e6..91850c271b 100644
--- a/core/src/main/java/hudson/tasks/Maven.java
+++ b/core/src/main/java/hudson/tasks/Maven.java
@@ -580,18 +580,12 @@ public class Maven extends Builder {
                 if (jars != null) { // be defensive
                     for (File jar : jars) {
                         if (jar.getName().startsWith("maven-")) {
-                            JarFile jf = null;
-                            try {
-                                jf = new JarFile(jar);
+                            try (JarFile jf = new JarFile(jar)) {
                                 Manifest manifest = jf.getManifest();
                                 String version = manifest.getMainAttributes().getValue(Attributes.Name.IMPLEMENTATION_VERSION);
                                 if (version != null) {
                                     return version;
                                 }
-                            } finally {
-                                if (jf != null) {
-                                    jf.close();
-                                }
                             }
                         }
                     }