宁静的Web服务对Java的帮助

Question

Below is my code which is giving a null pointer exception on execution. Please help me resolve this issue:

@POST
@GET
@Path("/Auth/{uname}")
public String checkUserAccess(@PathParam("uname") String username) {
    String message = svc.checkUserAccess(username);
    return message;
}

Service Interface:

public String checkUserAccess(String id);

Service Implementation:

public String checkUserAccess(String id) {
    String message = Dao.checkUserAccess(id);
    return message;
}

DAO Interface:

public String checkUserAccess(String id);

DAO Implementation:

public String checkUserAccess(String id) {
    String result = null;
    String user = propertyProvider.getProperty("Auth");
    if (user.equalsIgnoreCase(id))
        result = "Valid User";
    else
        result = "Invalid User";
    return result;
}

Answer 1

I guess the line of code where you are getting user from property provider is causing the NullPointerException . ie

String user = propertyProvider.getProperty("Auth");

I guess you are getting user as null . So if( user.equalsIgnoreCase(id) ) is throwing NullPointerException . Put a null check before authenticating the user.

if(user!=null && user.equalsIgnoreCase(id) ) {
    result = "Valid User"; 
else 
    result = "Invalid User"; 
return result; }