How can I set the region (=set of java Elements) parameter in JDT TypeHierarchy?

http://www.google.com/url?sa=t&rct=j&q=jdt_fundamentals&source=web&cd=1&ved=0CDIQFjAA&url=http%3A%2F%2Fwww.eclipsecon.org%2F2008%2Fsub%2Fattachments%2FJDT_fundamentals.ppt">JDT Tutorial an example code to get the type hierarchy using JDT.

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How can I set the region (=set of java Elements) parameter? When I have code A that has SubClass B, and SuperClass C. How can I set the region?

Solution

This code that I got hint from this site works fine.

IRegion region = JavaCore.newRegion();
for (IJavaElement i : javaProject.getPackageFragmentRoots())
{
    String elementName = i.getElementName();
    if (!elementName.endsWith("jar") && !elementName.endsWith("zip"))
        region.add(i);
    }

    NullProgressMonitor progressMonitor = new  NullProgressMonitor();

    // for getting a class hierarchy for type
    ITypeHierarchy typeHierarchy= type.newTypeHierarchy(progressMonitor);
    // for getting all the class hierarchies of the region in the project
    ITypeHierarchy typeHierarchy= javaProject.newTypeHierarchy(region, progressMonitor);
}