I am trying to get a reference to the ResourceResolver from the ResourceResolverFactory but got Null pointer Exception

Question

      Map<String, Object> param = new HashMap<String, Object>();
      param.put(ResourceResolverFactory.SUBSERVICE,"datawrite");
      log.info("param created."); 
      ResourceResolver resolver = null;  
    try {
         resolver=resolverFactory.getResourceResolver(param);
         log.info("resolveer created.");   
      Session session = resolver.adaptTo(Session.class);
      log.info("Session created.");
        // Create a node that represents the root node
        Node root = session.getRootNode();
        // Get the content node in the JCR
        Node content = root.getNode("/content");        
        Node customerRoot = null;
        int custRec = doesCustExist(content);
                log.info("does Customer Exist : "+ custRec);
        // -1 means that content/customer does not exist
        if (custRec == -1) {
            // content/customer does not exist -- create it
            customerRoot = content.addNode("customer");
        } else {
            // content/customer does exist -- retrieve it
            customerRoot = content.getNode("customer");
        }

        int custId = custRec + 1; // assign a new id to the customer node
    // Store content from the client JSP in the JCR
        Node custNode = customerRoot.addNode("customer" + firstName + lastName + phone+desc);
    // make sure name of node is unique
        custNode.setProperty("id", custId);
        custNode.setProperty("firstName", firstName);
        custNode.setProperty("lastName", lastName);
        custNode.setProperty("phone", phone);
        custNode.setProperty("desc", desc);
        // Save the session changes and log out
        session.save();
        session.logout();
        return custId;
    }
catch (Exception e) {
        log.error("RepositoryException: " + e);
    }

i got this error:

ERROR [0:0:0:0:0:0:0:1 [1567433510240] GET /bin/abc HTTP/1.1] aem.community.mf.core.servlets.SaveJcrData RepositoryException: java.lang.NullPointerException

Answer 1

You can solve this problem in two ways:

1. Try using ResourceResolverFactory in servlet itself, means you should define it in servlet itself and use it there for getting resources and use

 resolver=req.getResourceResolver();

instead of

resolver=resolverFactory.getResourceResolver(param);

2. You should ensure that your class should be annotated as @Component and then try to get resources in that class as follows:

@Component
public class SaveJcrData implements SaveService {

    protected final Logger log = LoggerFactory.getLogger(this.getClass());

    @Reference
    private SlingRepository repository;

    @Reference
    private ResourceResolverFactory resolverFactory;

    private Session session;

    public void bindRepository(SlingRepository repository) {
        this.repository = repository;
    }

//Stores customer data in the Adobe CQ JCR
    public int injestData(String firstName, String lastName, String phone, String desc) throws Exception {

        Map<String, Object> param = new HashMap<String, Object>();
        param.put(ResourceResolverFactory.SUBSERVICE, "datawrite");
        ResourceResolver resolver = null;
        try {

            // Invoke the adaptTo method to create a Session used to create a QueryManager
            log.trace("In try.");
            resolver = resolverFactory.getServiceResourceResolver(param);                                                                           
                                                                            
            log.trace("resolveer created.");
            Session session = resolver.adaptTo(Session.class);
            log.info("Session created.");