Continuation: New To Java: How To Install JFace?

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I already got the jar file but during object creation it gives an error message "Exception in thread "main" java.lang.NoClassDefFoundError: org/eclipse/core/runtime/ISafeRunnable"

here's the code where the exception occurred:

Code:

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// mShell variable was successfully created
ListViewer listViewer;
listViewer = new ListViewer(mShell); // <- exception occurred

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Please assist me on this.