diff --git a/CONTRIBUTORS b/CONTRIBUTORS
index 5dea6ecda..45c04e1eb 100644
--- a/CONTRIBUTORS
+++ b/CONTRIBUTORS
@@ -242,6 +242,7 @@ Ulrich Schmidt
 Waldek Herka
 Will Wang
 William Ferguson
+Wolfgang Frech
 Wolfgang Werner
 Wolf Siberski
 Yohann Roussel
diff --git a/contributors.xml b/contributors.xml
index 70fe5576e..24ae73a23 100644
--- a/contributors.xml
+++ b/contributors.xml
@@ -958,6 +958,10 @@
     <first>William</first>
     <last>Ferguson</last>
   </name>
+  <name>
+    <first>Wolfgang</first>
+    <last>Frech</last>
+  </name>
   <name>
     <first>Wolfgang</first>
     <last>Werner</last>
diff --git a/docs/manual/CoreTasks/java.html b/docs/manual/CoreTasks/java.html
index 3315c99aa..38b386591 100644
--- a/docs/manual/CoreTasks/java.html
+++ b/docs/manual/CoreTasks/java.html
@@ -288,12 +288,15 @@ exit, as the class was run by the build JVM.</p>
 
 <h3>JAR file execution</h3>
 
-The parameter of the <tt>jar</tt> attribute is of type <tt>File</tt>;
+<p>The parameter of the <tt>jar</tt> attribute is of type <tt>File</tt>;
 that is, the parameter is resolved to an absolute file relative to the
 base directory of the project, <i>not</i> the directory in which the Java
 task is run. If you need to locate a JAR file relative to the directory
 the task will be run in, you need to explicitly create the full path
-to the JAR file.
+to the JAR file.</p>
+<p>When using the <tt>jar</tt> attribute, all classpath settings are 
+ignored according to <a href="http://java.sun.com/j2se/1.5.0/docs/tooldocs/windows/java.html#-jar">Sun's
+specification</a>. 
 
 
 <h3>Examples</h3>
@@ -355,14 +358,14 @@ Runs a given class with the current classpath.
     &lt;jvmarg value=&quot;-Xrunhprof:cpu=samples,file=log.txt,depth=3&quot;/&gt;
   &lt;/java&gt;
 </pre>
-Add system properties and JVM-properties to the JVM as in 
+Add system properties and JVM-properties to the JVM as in
 <code>java ="-Xrunhprof:cpu=samples,file=log.txt,depth=3 -DDEBUG=true test.Main</code>
 
 <pre>  &lt;java classname=&quot;ShowJavaVersion&quot; classpath=&quot;.&quot;
         jvm=&quot;path-to-java14-home/bin/java&quot; fork=&quot;true&quot;
         taskname=&quot;java1.4&quot; &gt;
 </pre>
-Use a given Java implementation (another the one Ant is currently using) to run the class. 
+Use a given Java implementation (another the one Ant is currently using) to run the class.
 For documentation in the log <code>taskname</code> is used to change the <code>[java]</code>
 log-prefix to <code>[java1.4]</code>.
 
diff --git a/src/main/org/apache/tools/ant/taskdefs/Java.java b/src/main/org/apache/tools/ant/taskdefs/Java.java
index 4f8aa42bd..aed95cfb6 100644
--- a/src/main/org/apache/tools/ant/taskdefs/Java.java
+++ b/src/main/org/apache/tools/ant/taskdefs/Java.java
@@ -116,7 +116,7 @@ public class Java extends Task {
      * Do the execution and return a return code.
      *
      * @return the return code from the execute java class if it was
-     * executed in a separate VM (fork = "yes") or a security manager was 
+     * executed in a separate VM (fork = "yes") or a security manager was
      * installed that prohibits ExitVM (default).
      *
      * @throws BuildException if required parameters are missing.
@@ -134,6 +134,10 @@ public class Java extends Task {
             throw new BuildException("Cannot spawn a java process in non-forked mode."
                                      + " Please set fork='true'. ");
         }
+        if (cmdl.getClasspath()!=null && cmdl.getJar()!=null) {
+            log("When using 'jar' attribute classpath-settings are ignored. "
+                + "See the manual for more information.", Project.MSG_VERBOSE);
+        }
         if (spawn && incompatibleWithSpawn) {
             getProject().log("spawn does not allow attributes related to input, "
             + "output, error, result", Project.MSG_ERR);
@@ -925,4 +929,4 @@ public class Java extends Task {
     public CommandlineJava.SysProperties getSysProperties() {
         return cmdl.getSystemProperties();
     }
-}
+}
\ No newline at end of file