diff -r 23ff9c8995c6 xml.core/src/org/netbeans/modules/xml/api/XmlFileEncodingQueryImpl.java
--- a/xml.core/src/org/netbeans/modules/xml/api/XmlFileEncodingQueryImpl.java	Mon Mar 10 14:16:31 2008 +0100
+++ b/xml.core/src/org/netbeans/modules/xml/api/XmlFileEncodingQueryImpl.java	Mon Mar 10 14:56:36 2008 +0100
@@ -36,6 +36,8 @@ import java.nio.charset.CharsetDecoder;
 import java.nio.charset.CharsetDecoder;
 import java.nio.charset.CharsetEncoder;
 import java.nio.charset.CoderResult;
+import java.nio.charset.IllegalCharsetNameException;
+import java.nio.charset.UnsupportedCharsetException;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import org.netbeans.spi.queries.FileEncodingQueryImplementation;
@@ -141,7 +143,18 @@ public final class XmlFileEncodingQueryI
                 return null;
             }
             else {
-                Charset c = Charset.forName(encoding);
+                Charset c;
+                try {
+                    c = Charset.forName(encoding);
+                } catch (UnsupportedCharsetException e) {
+                    buffer = null;
+                    throwUnknownEncoding();
+                    return null;
+                } catch (IllegalCharsetNameException e) {
+                    buffer = null;
+                    throwUnknownEncoding();
+                    return null;
+                }
                 encoder = c.newEncoder();
                 LOG.log (Level.FINEST,ENCODER_SELECTED,encoder);
                 return flushHead(in, out);
@@ -261,7 +274,18 @@ public final class XmlFileEncodingQueryI
                 return null;
             }
             else {
-                Charset c = Charset.forName(encoding);
+                Charset c;
+                try {
+                    c = Charset.forName(encoding);
+                } catch (UnsupportedCharsetException e) {
+                    buffer = null;
+                    throwUnknownEncoding();
+                    return null;
+                } catch (IllegalCharsetNameException e) {
+                    buffer = null;
+                    throwUnknownEncoding();
+                    return null;
+                }
                 decoder = c.newDecoder();
                 LOG.log (Level.FINEST,DECODER_SELECTED,decoder);
                 return flushHead(in, out);
diff -r 23ff9c8995c6 xml.core/test/unit/src/org/netbeans/modules/xml/api/data/data.properties
--- a/xml.core/test/unit/src/org/netbeans/modules/xml/api/data/data.properties	Mon Mar 10 14:16:31 2008 +0100
+++ b/xml.core/test/unit/src/org/netbeans/modules/xml/api/data/data.properties	Mon Mar 10 14:56:36 2008 +0100
@@ -2,3 +2,5 @@ long_encoding.xml=ISO-8859-2
 long_encoding.xml=ISO-8859-2
 short_no_encoding.xml=<null>
 long_no_encoding.xml=<null>
+illegal_encoding.xml=<null>
+unsupported_encoding.xml=<null>
diff -r 23ff9c8995c6 xml.core/test/unit/src/org/netbeans/modules/xml/api/data/illegal_encoding.xml
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xml.core/test/unit/src/org/netbeans/modules/xml/api/data/illegal_encoding.xml	Mon Mar 10 14:56:36 2008 +0100
@@ -0,0 +1,4 @@
+<?xml version='1.0' encoding='$$$' ?> 
+<root>
+Short XML file test.
+</root>
diff -r 23ff9c8995c6 xml.core/test/unit/src/org/netbeans/modules/xml/api/data/unsupported_encoding.xml
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xml.core/test/unit/src/org/netbeans/modules/xml/api/data/unsupported_encoding.xml	Mon Mar 10 14:56:36 2008 +0100
@@ -0,0 +1,4 @@
+<?xml version='1.0' encoding='unknown' ?> 
+<root>
+Short XML file test.
+</root>