nullpointerexception

问题 I've read here why Optional.of() should be used over Optional.ofNullable() , but the answer didn't satisfy me at all, so I ask slightly different: If you are SURE that your method does not return null , why should you use Optional at all? As far as I know, the more or less only purpose of it is to remind the "user of a method", that he might have to deal with null -values. If he does not have to deal with null -values, why should he be bothered with an Optional ? I ask, because I recently

问题 No matter what I try, SplashScreen.getSplashScreen() is always null . From searching online I see that this is a common issue, and that it has something to do with not giving the SplashScreen an image to use... Therefore, in navigating the methods it seemed to me that setImageURL(URL) should be used. This is still not working. There are similar questions on SO, such as this, which are not helpful and seem to suggest using a myriad of plugins or creating such a class from scratch extending

问题 This question already has answers here : Booleans, conditional operators and autoboxing (4 answers) Closed 5 years ago . I am getting NullPointerException in one instance below while its counterpart runs smooth. public static void main(String[] args){ System.out.println(withTernary(null, null)); //Null Pointer System.out.println(withIfElse(null, null)); //No Exception } private static Boolean withTernary(String val, Boolean defVal){ return val == null ? defVal : "true".equalsIgnoreCase(val);

问题 This question already has answers here : Booleans, conditional operators and autoboxing (4 answers) Closed 5 years ago . I am getting NullPointerException in one instance below while its counterpart runs smooth. public static void main(String[] args){ System.out.println(withTernary(null, null)); //Null Pointer System.out.println(withIfElse(null, null)); //No Exception } private static Boolean withTernary(String val, Boolean defVal){ return val == null ? defVal : "true".equalsIgnoreCase(val);

问题 I have a google map in a fragment in my application. Funny thing is that the map loads, but the logcat displays a NullPointerException , and I only noticed it when tried to update the camera on the map so that it could automatically zoom in on the marker . Only then the map will crash. Otherwise, the map loads fine in the fragment but with no marker (even though I am adding one using my current gps location ). EDITED* I understand that its crashing because the googleMap is null, but I don't

问题 This question already has answers here : Retrofit 2 - null response body (1 answer) What is a NullPointerException, and how do I fix it? (12 answers) Closed 3 years ago . I'm trying to get data from web API, but something is wrong in my onResponse() method and I can't figure it out. My JSON looks like this [ "partner1", "partner2", "partner3", ... , "partner150" ] I have Table partners (ActiveAndroid) in which I would like to save all partners from the API. @Table(name = "Partners") public

问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 4 months ago . I have a TextField in which there is some text but I want to change that text on some event but I am getting the NullPointerException . I am using setText() method but still its not working. I am calling that function from other class . Any Help? Thanks in advance. 回答1: At beginning of the controller's class

问题 Am developing a JavaEE application using Netbeans.The Entity Manager is getting a null value in the application. The em is not getting injected. Still am getting a nullPointerException as em is getting a null value in createNamedQuery. Could anyone please let me know what am I missing. JSP page- index.jsp: <%@page import="managed.userBean" %> <jsp:useBean id="bean" class="managed.userBean" scope="session" /> ..... <input type="submit" value="Submit" onclick="<jsp:scriptlet> bean.validate();<

问题 I am using a Sinch tutorial(https://github.com/sinch/android-app-app-calling-headers) as a framework for an app I am trying to develop. The following is the login class from the tutorial which I have updated and been successful in initializing the sinch client. public class LoginActivity extends BaseActivity implements SinchService.StartFailedListener { private Button mLoginButton; private EditText mLoginName; private static final int REQUEST_PERMISSION = 10; @Override protected void onCreate

问题 This question already has answers here : What is a NullPointerException, and how do I fix it? (12 answers) Closed 3 years ago . I am new to JSON. I need help. My android studio keeps on telling me that my jsonobject is NULL. I can parse and display my jsonarray into a listview. But when i click the page where i displayed it, my app crashes. Parser class BgTask extends AsyncTask<Void, Void, String> { String json_url; @Override protected void onPreExecute() { json_url = "http://10.0.2.2/result