### Eclipse Workspace Patch 1.0
#P org.eclipse.jdt.core
Index: model/org/eclipse/jdt/internal/core/JavaProject.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/JavaProject.java,v
retrieving revision 1.440
diff -u -r1.440 JavaProject.java
--- model/org/eclipse/jdt/internal/core/JavaProject.java	24 Nov 2010 01:33:28 -0000	1.440
+++ model/org/eclipse/jdt/internal/core/JavaProject.java	9 Dec 2010 18:17:17 -0000
@@ -1555,12 +1555,11 @@
 				token = null;
 				while (memento.hasMoreTokens()) {
 					token = memento.nextToken();
-					char firstChar = token.charAt(0);
-					if (firstChar != JEM_PACKAGEFRAGMENT && firstChar != JEM_COUNT) {
-						rootPath += token;
-					} else {
+					// https://bugs.eclipse.org/bugs/show_bug.cgi?id=331821
+					if (token == MementoTokenizer.PACKAGEFRAGMENT || token == MementoTokenizer.COUNT) {
 						break;
 					}
+					rootPath += token;
 				}
 				JavaElement root = (JavaElement)getPackageFragmentRoot(new Path(rootPath));
 				if (token != null && token.charAt(0) == JEM_PACKAGEFRAGMENT) {
Index: model/org/eclipse/jdt/internal/core/util/MementoTokenizer.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/util/MementoTokenizer.java,v
retrieving revision 1.9
diff -u -r1.9 MementoTokenizer.java
--- model/org/eclipse/jdt/internal/core/util/MementoTokenizer.java	27 Jun 2008 16:03:57 -0000	1.9
+++ model/org/eclipse/jdt/internal/core/util/MementoTokenizer.java	9 Dec 2010 18:17:17 -0000
@@ -13,21 +13,21 @@
 import org.eclipse.jdt.internal.core.JavaElement;
 
 public class MementoTokenizer {
-	private static final String COUNT = Character.toString(JavaElement.JEM_COUNT);
-	private static final String JAVAPROJECT = Character.toString(JavaElement.JEM_JAVAPROJECT);
-	private static final String PACKAGEFRAGMENTROOT = Character.toString(JavaElement.JEM_PACKAGEFRAGMENTROOT);
-	private static final String PACKAGEFRAGMENT = Character.toString(JavaElement.JEM_PACKAGEFRAGMENT);
-	private static final String FIELD = Character.toString(JavaElement.JEM_FIELD);
-	private static final String METHOD = Character.toString(JavaElement.JEM_METHOD);
-	private static final String INITIALIZER = Character.toString(JavaElement.JEM_INITIALIZER);
-	private static final String COMPILATIONUNIT = Character.toString(JavaElement.JEM_COMPILATIONUNIT);
-	private static final String CLASSFILE = Character.toString(JavaElement.JEM_CLASSFILE);
-	private static final String TYPE = Character.toString(JavaElement.JEM_TYPE);
-	private static final String PACKAGEDECLARATION = Character.toString(JavaElement.JEM_PACKAGEDECLARATION);
-	private static final String IMPORTDECLARATION = Character.toString(JavaElement.JEM_IMPORTDECLARATION);
-	private static final String LOCALVARIABLE = Character.toString(JavaElement.JEM_LOCALVARIABLE);
-	private static final String TYPE_PARAMETER = Character.toString(JavaElement.JEM_TYPE_PARAMETER);
-	private static final String ANNOTATION = Character.toString(JavaElement.JEM_ANNOTATION);
+	public static final String COUNT = Character.toString(JavaElement.JEM_COUNT);
+	public static final String JAVAPROJECT = Character.toString(JavaElement.JEM_JAVAPROJECT);
+	public static final String PACKAGEFRAGMENTROOT = Character.toString(JavaElement.JEM_PACKAGEFRAGMENTROOT);
+	public static final String PACKAGEFRAGMENT = Character.toString(JavaElement.JEM_PACKAGEFRAGMENT);
+	public static final String FIELD = Character.toString(JavaElement.JEM_FIELD);
+	public static final String METHOD = Character.toString(JavaElement.JEM_METHOD);
+	public static final String INITIALIZER = Character.toString(JavaElement.JEM_INITIALIZER);
+	public static final String COMPILATIONUNIT = Character.toString(JavaElement.JEM_COMPILATIONUNIT);
+	public static final String CLASSFILE = Character.toString(JavaElement.JEM_CLASSFILE);
+	public static final String TYPE = Character.toString(JavaElement.JEM_TYPE);
+	public static final String PACKAGEDECLARATION = Character.toString(JavaElement.JEM_PACKAGEDECLARATION);
+	public static final String IMPORTDECLARATION = Character.toString(JavaElement.JEM_IMPORTDECLARATION);
+	public static final String LOCALVARIABLE = Character.toString(JavaElement.JEM_LOCALVARIABLE);
+	public static final String TYPE_PARAMETER = Character.toString(JavaElement.JEM_TYPE_PARAMETER);
+	public static final String ANNOTATION = Character.toString(JavaElement.JEM_ANNOTATION);
 
 	private final char[] memento;
 	private final int length;
#P org.eclipse.jdt.core.tests.model
Index: src/org/eclipse/jdt/core/tests/model/MementoTests.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core.tests.model/src/org/eclipse/jdt/core/tests/model/MementoTests.java,v
retrieving revision 1.29
diff -u -r1.29 MementoTests.java
--- src/org/eclipse/jdt/core/tests/model/MementoTests.java	24 Nov 2010 01:33:28 -0000	1.29
+++ src/org/eclipse/jdt/core/tests/model/MementoTests.java	9 Dec 2010 18:17:19 -0000
@@ -92,7 +92,7 @@
 		"1.4");
 	this.createJavaProject(
 			"P",
-			new String[] {"src"},
+			new String[] {"src", "!"},
 			new String[] {
 				getExternalJCLPathString(),
 				"/P/lib",
@@ -794,4 +794,15 @@
 		"=P/src<p{X.java[X~foo]T",
 		typeParameter);
 }
+/*
+ * Test that a package fragment root name starting with '!' can be reconstructed from
+ * the handle identifier.
+ * https://bugs.eclipse.org/bugs/show_bug.cgi?id=331821
+ */
+public void testBug331821() throws JavaModelException {
+	IPackageFragmentRoot root = getPackageFragmentRoot("P", "!");
+	String handleIdentifier = root.getHandleIdentifier();
+	IPackageFragmentRoot newRoot = (IPackageFragmentRoot) JavaCore.create(handleIdentifier);
+	assertEquals(root, newRoot);
+}
 }