diff --git a/src/main/org/apache/tools/ant/IntrospectionHelper.java b/src/main/org/apache/tools/ant/IntrospectionHelper.java
index 30086563b..719f22d9d 100644
--- a/src/main/org/apache/tools/ant/IntrospectionHelper.java
+++ b/src/main/org/apache/tools/ant/IntrospectionHelper.java
@@ -407,6 +407,7 @@ public final class IntrospectionHelper {
                     + " doesn't support the \"" + attributeName + "\" attribute.";
             throw new UnsupportedAttributeException(msg, attributeName);
         }
+        if (as != null) { // possible if value == null
         try {
             as.setObject(p, element, value);
         } catch (final IllegalAccessException ie) {
@@ -415,6 +416,7 @@ public final class IntrospectionHelper {
         } catch (final InvocationTargetException ite) {
             throw extractBuildException(ite);
         }
+        }
     }
 
     /**
diff --git a/src/main/org/apache/tools/ant/taskdefs/Javadoc.java b/src/main/org/apache/tools/ant/taskdefs/Javadoc.java
index f3c16ced0..b7fb41772 100644
--- a/src/main/org/apache/tools/ant/taskdefs/Javadoc.java
+++ b/src/main/org/apache/tools/ant/taskdefs/Javadoc.java
@@ -1772,10 +1772,12 @@ public class Javadoc extends Task {
                 useExternalFile, tmpList, srcListWriter);
 
             if (useExternalFile) {
-                srcListWriter.flush();
+                srcListWriter.flush(); //NOSONAR
             }
         } catch (final IOException e) {
-            tmpList.delete();
+            if (tmpList != null) {
+                tmpList.delete();
+            }
             throw new BuildException("Error creating temporary file",
                                      e, getLocation());
         } finally {
diff --git a/src/main/org/apache/tools/ant/taskdefs/XmlProperty.java b/src/main/org/apache/tools/ant/taskdefs/XmlProperty.java
index 2830bdf9c..ffd89d1c1 100644
--- a/src/main/org/apache/tools/ant/taskdefs/XmlProperty.java
+++ b/src/main/org/apache/tools/ant/taskdefs/XmlProperty.java
@@ -384,10 +384,12 @@ public class XmlProperty extends org.apache.tools.ant.Task {
                     if (containingPath != null && nodeName.equals(PATH)) {
                         // A "path" attribute for a node within a Path object.
                         containingPath.setPath(attributeValue);
-                    } else if (container instanceof Path && nodeName.equals(REF_ID)) {
+                    } else if (containingPath != null
+                               && container instanceof Path && nodeName.equals(REF_ID)) {
                         // A "refid" attribute for a node within a Path object.
                         containingPath.setPath(attributeValue);
-                    } else if (container instanceof Path && nodeName.equals(LOCATION)) {
+                    } else if (containingPath != null && container instanceof Path
+                               && nodeName.equals(LOCATION)) {
                         // A "location" attribute for a node within a
                         // Path object.
                         containingPath.setLocation(resolveFile(attributeValue));
diff --git a/src/main/org/apache/tools/ant/taskdefs/optional/depend/Depend.java b/src/main/org/apache/tools/ant/taskdefs/optional/depend/Depend.java
index cc65129f9..2cf335cbe 100644
--- a/src/main/org/apache/tools/ant/taskdefs/optional/depend/Depend.java
+++ b/src/main/org/apache/tools/ant/taskdefs/optional/depend/Depend.java
@@ -197,7 +197,7 @@ public class Depend extends MatchingTask {
                     dependencyList = new Vector();
                     className = line.substring(prependLength);
                     dependencyMap.put(className, dependencyList);
-                } else {
+                } else if (dependencyList != null) {
                     dependencyList.addElement(line);
                 }
             }
diff --git a/src/main/org/apache/tools/ant/taskdefs/optional/jdepend/JDependTask.java b/src/main/org/apache/tools/ant/taskdefs/optional/jdepend/JDependTask.java
index 9d2e9ae68..c608583b1 100644
--- a/src/main/org/apache/tools/ant/taskdefs/optional/jdepend/JDependTask.java
+++ b/src/main/org/apache/tools/ant/taskdefs/optional/jdepend/JDependTask.java
@@ -553,7 +553,7 @@ public class JDependTask extends Task {
             }
 
             jdepend.analyze();
-            if (pw.checkError()) {
+            if (pw != null && pw.checkError()) {
                 throw new IOException("Encountered an error writing JDepend"
                                       + " output");
             }
diff --git a/src/main/org/apache/tools/ant/taskdefs/optional/sound/AntSoundPlayer.java b/src/main/org/apache/tools/ant/taskdefs/optional/sound/AntSoundPlayer.java
index f2ad68618..aef214fe0 100644
--- a/src/main/org/apache/tools/ant/taskdefs/optional/sound/AntSoundPlayer.java
+++ b/src/main/org/apache/tools/ant/taskdefs/optional/sound/AntSoundPlayer.java
@@ -133,7 +133,9 @@ public class AntSoundPlayer implements LineListener, BuildListener {
                 } else {
                     playClip(audioClip, loops);
                 }
-                audioClip.drain();
+                if (audioClip != null) {
+                    audioClip.drain();
+                }
             } finally {
                 if (audioClip != null) {
                     audioClip.close();
diff --git a/src/main/org/apache/tools/tar/TarEntry.java b/src/main/org/apache/tools/tar/TarEntry.java
index de15a1c71..67990797a 100644
--- a/src/main/org/apache/tools/tar/TarEntry.java
+++ b/src/main/org/apache/tools/tar/TarEntry.java
@@ -333,7 +333,7 @@ public class TarEntry implements TarConstants {
      * @return True if the entries are equal.
      */
     public boolean equals(TarEntry it) {
-        return getName().equals(it.getName());
+        return it != null && getName().equals(it.getName());
     }
 
     /**