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POJDT SearchEngine throws a NullPointerException
 

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  1. POJDT SearchEngine throws a NullPointerException
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    <p>I'm trying to use JDT SearchEngine to find references to a given object. But I'm getting a "NullPointerException" while invoking the "search" method of org.eclipse.jdt.core.search.SearchEngine.</p> <p>Following is the error trace:</p> <blockquote> <p>java.lang.NullPointerException at org.eclipse.jdt.internal.core.search.BasicSearchEngine.findMatches(BasicSearchEngine.java:214) at org.eclipse.jdt.internal.core.search.BasicSearchEngine.search(BasicSearchEngine.java:515) at org.eclipse.jdt.core.search.SearchEngine.search(SearchEngine.java:582)</p> </blockquote> <p>And following is the method I'm using to perform search:</p> <pre class="lang-java prettyprint-override"><code>private static void search(String elementName) { //elementName -&gt; a method Name try { SearchPattern pattern = SearchPattern.createPattern(elementName, IJavaSearchConstants.METHOD, IJavaSearchConstants.REFERENCES, SearchPattern.R_PATTERN_MATCH); IJavaSearchScope scope = SearchEngine.createWorkspaceScope(); SearchRequestor requestor = new SearchRequestor() { @Override public void acceptSearchMatch(SearchMatch match) { System.out.println("Element - " + match.getElement()); } }; SearchEngine searchEngine = new SearchEngine(); SearchParticipant[] searchParticipants = new SearchParticipant[] { SearchEngine .getDefaultSearchParticipant() }; searchEngine.search(pattern, searchParticipants, scope, requestor, null); } catch (Exception e) { e.printStackTrace(); } } </code></pre> <p>Refer the "Variables" window of the following snapshot to check the values of the arguments passing to the "searchEngine.search()":</p> <p><img src="https://i.stack.imgur.com/1wCo8.png" alt="enter image description here"></p> <p>I think the the issue is because of the value of "scope" [Highlighted in 'BLACK' above]. Which means "SearchEngine.createWorkspaceScope()" doesn't return expected values in this case. </p> <p><strong>NOTE:</strong> Please note that this is a part of my program which runs as a stand-alone java program (not an eclipse plugin) using JDT APIs to parse a given source code (using JDT-AST). </p> <p>Isn't it possible to use JDT SearchEngine in such case (non eclipse plugin program), or is this issue due to some other reason? Really appreciate your answer on this.</p>
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    1. USBhanuka Withana
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    1. COMy suggestion would be to create a stand-alone plug-in program, using tools such as Eclipse RCP. This will keep the application as standalone and you will also be able to access the workspace via configuration files, thus enabling the use of the JDT search engine.
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      1. USUnni Kris
    2. COThanks for your suggestion. But in my case, I can't limit my implementation only for Eclipse projects. Basically, my application handles a given java source code base and it should be capable of handling any type of java sources. So eclipse workspace configuration files may not be there in a given java project as an input to my application. However your suggestion might be useful for some other cases where that kind of a limitation is not there.
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      1. USBhanuka Withana
    3. COThen as Anrew Eisenberg suggested, you can go for a Custom Search Engine solution, probably using the ASTVisitor pattern.
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      1. USUnni Kris
 

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