### Eclipse Workspace Patch 1.0
#P org.eclipse.jdt.core
Index: model/org/eclipse/jdt/internal/core/JavaModelManager.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/JavaModelManager.java,v
retrieving revision 1.454
diff -u -r1.454 JavaModelManager.java
--- model/org/eclipse/jdt/internal/core/JavaModelManager.java	21 Jul 2010 14:13:46 -0000	1.454
+++ model/org/eclipse/jdt/internal/core/JavaModelManager.java	2 Sep 2010 03:46:35 -0000
@@ -997,9 +997,8 @@
 			JavaProjectElementInfo projectInfo = (JavaProjectElementInfo) getJavaModelManager().getInfo(project);
 			ProjectCache projectCache = projectInfo == null ? null : projectInfo.projectCache;
 			HashtableOfArrayToObject allPkgFragmentsCache = projectCache == null ? null : projectCache.allPkgFragmentsCache;
-			IClasspathEntry[] entries =
-				org.eclipse.jdt.internal.core.util.Util.isJavaLikeFileName(resourcePath.lastSegment())
-					? project.getRawClasspath() // JAVA file can only live inside SRC folder (on the raw path)
+			boolean isJavaLike = org.eclipse.jdt.internal.core.util.Util.isJavaLikeFileName(resourcePath.lastSegment());
+			IClasspathEntry[] entries = isJavaLike ? project.getRawClasspath() // JAVA file can only live inside SRC folder (on the raw path)
 					: ((JavaProject)project).getResolvedClasspath();
 
 			int length	= entries.length;
@@ -1011,6 +1010,8 @@
 					if (entry.getEntryKind() == IClasspathEntry.CPE_PROJECT) continue;
 					IPath rootPath = entry.getPath();
 					if (rootPath.equals(resourcePath)) {
+						if (isJavaLike) 
+							return null;
 						return project.getPackageFragmentRoot(resource);
 					} else if (rootPath.isPrefixOf(resourcePath)) {
 						// allow creation of package fragment if it contains a .java file that is included
#P org.eclipse.jdt.core.tests.model
Index: src/org/eclipse/jdt/core/tests/model/ClasspathTests.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core.tests.model/src/org/eclipse/jdt/core/tests/model/ClasspathTests.java,v
retrieving revision 1.215
diff -u -r1.215 ClasspathTests.java
--- src/org/eclipse/jdt/core/tests/model/ClasspathTests.java	27 May 2010 10:10:45 -0000	1.215
+++ src/org/eclipse/jdt/core/tests/model/ClasspathTests.java	2 Sep 2010 03:46:38 -0000
@@ -6747,5 +6747,26 @@
 		ContainerInitializer.setInitializer(null);
 	}
 }
+public void testBug321170() throws Exception {
+	try {
+		IJavaProject p = this.createJavaProject("P", new String[] {}, "bin");
+		
+		IFile file = this.createFile("/P/bin/X.java", "public class X {}");
+		
+		IClasspathEntry[] classpath = new IClasspathEntry[1];
+		classpath[0] = JavaCore.newLibraryEntry(new Path("/P/bin/X.java"), null, null);
+		setClasspath(p, classpath);
+		ICompilationUnit element = (ICompilationUnit)JavaCore.create(file, p);
+		assertNotNull("File created", element);
+	}
+	catch(ClassCastException e){
+		fail("classcast exception");
+	}
+	finally {
+		deleteProject("P");
+		ContainerInitializer.setInitializer(null);
+	}
+}
+
 
 }