open a file from Eclipse project after triggering a command on a Java method

TestResultHandler

package com.windriver.installer.testtool.handlers;

import java.io.File;

import org.eclipse.core.commands.AbstractHandler;
import org.eclipse.core.commands.ExecutionEvent;
import org.eclipse.core.commands.ExecutionException;
import org.eclipse.core.filesystem.EFS;
import org.eclipse.core.filesystem.IFileStore;
import org.eclipse.core.resources.IProject;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.runtime.IPath;
import org.eclipse.ui.IEditorInput;
import org.eclipse.ui.IEditorPart;
import org.eclipse.ui.IFileEditorInput;
import org.eclipse.ui.IWorkbenchPage;
import org.eclipse.ui.IWorkbenchWindow;
import org.eclipse.ui.PartInitException;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.handlers.HandlerUtil;
import org.eclipse.ui.ide.IDE;
import org.eclipse.ui.texteditor.ITextEditor;
import org.eclipse.jdt.core.ICompilationUnit;
import org.eclipse.jdt.core.IJavaElement;
import org.eclipse.jdt.core.JavaModelException;
import org.eclipse.jdt.ui.JavaUI;
import org.eclipse.jface.dialogs.MessageDialog;
import org.eclipse.jface.text.ITextSelection;

/**
 * Our sample handler extends AbstractHandler, an IHandler base class.
 * 
 * @see org.eclipse.core.commands.IHandler
 * @see org.eclipse.core.commands.AbstractHandler
 */
public class TestResultHandler extends AbstractHandler {
	/**
	 * The constructor.
	 */
	public TestResultHandler() {
	}
	
	IResource extractResource(IEditorPart editor) {
	      IEditorInput input = editor.getEditorInput();
	      if (!(input instanceof IFileEditorInput))
	         return null;
	      return ((IFileEditorInput)input).getFile();
	   }

	/**
	 * the command has been executed, so extract extract the needed information
	 * from the application context.
	 */
	public Object execute(ExecutionEvent event) throws ExecutionException {
		ITextEditor editor = (ITextEditor) PlatformUI.getWorkbench()
				.getActiveWorkbenchWindow().getActivePage().getActiveEditor();

		if (editor != null) {
			ITextSelection selection = (ITextSelection) editor
					.getSelectionProvider().getSelection();

			IEditorInput editorInput = editor.getEditorInput();
			IJavaElement elem = JavaUI.getEditorInputJavaElement(editorInput);
			if (elem instanceof ICompilationUnit) {
				ICompilationUnit unit = (ICompilationUnit) elem;
				try {
					IJavaElement selected = unit.getElementAt(selection
							.getOffset());
					if (selected != null) {
						String methodName = selected.getElementName();
						IProject project = extractResource(editor).getProject();
						File rtFile = new File(project.getLocation().toFile(), methodName + ".txt"); 
						if (rtFile.exists()) {
							IFileStore fileStore = EFS.getLocalFileSystem().getStore(rtFile.toURI());
						    IWorkbenchPage page = PlatformUI.getWorkbench().getActiveWorkbenchWindow().getActivePage();
						 
						    try {
						        IDE.openEditorOnFileStore( page, fileStore );
						    } catch ( PartInitException e ) {
						        //Put your exception handler here if you wish to
						    }
						}
					}
				} catch (JavaModelException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
		}

		return null;
	}
}