nullpointerexception

问题 I have an action URL after clicking a hyper link like so /SocialStupendous/GetProfile.action?slno=3&slno=3 In my execute method of ActionClass I have the following code public String execute() { int urislno=Integer.parseInt(getServletRequest().getParameter("slno")); System.out.println(urislno); bean.setUslno(urislno); } I am getting NullPointerException when I am performing bean.setuslno(urislno) . Even though urislno is printed properly as 3 . ProfileBean class: public class ProfileBean {

问题 I have an action URL after clicking a hyper link like so /SocialStupendous/GetProfile.action?slno=3&slno=3 In my execute method of ActionClass I have the following code public String execute() { int urislno=Integer.parseInt(getServletRequest().getParameter("slno")); System.out.println(urislno); bean.setUslno(urislno); } I am getting NullPointerException when I am performing bean.setuslno(urislno) . Even though urislno is printed properly as 3 . ProfileBean class: public class ProfileBean {

问题 I'm absolutely new in Java. I have the following problem: method readLine() or nextLine() , nextInt() etc. throw an exception: NullPointerException . I use NetBeans IDE(if it matters). public static void Reading() { String qq; qq = System.console().readLine(); System.console().printf(qq); } 回答1: Some IDEs don't provide a console. Note that System.console() returns null in these cases. From the documentanion Returns: The system console, if any, otherwise null. You can always use System.in and

问题 My code is breaking on the following line with a nullpointerexception: if (stringVariable.equals(null)){ Previous to this statement, I declare the stringVariable and set it to a database field. In this statement, I am trying to detect if the field had a null value, but unfortunately it breaks! Any thoughts? 回答1: Use stringVariable == null To test whether stringVariable is null . The equals method (and every other method) requires stringVariable to not be null . 回答2: if stringvariable is

问题 I am using butterknife 8.0.1 , but a nullpointerexception is appearing. This line is on my build.grade file: compile 'com.jakewharton:butterknife:8.0.1' this is my Main Class: (I wrote the includes properly) import butterknife.BindView; import butterknife.ButterKnife; public class MainActivity extends BaseActivity { @BindView(R.id.MainScreenTextView) TextView mainText; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout

问题 I am working on a game where the player can drag and drop things around the screen. I've got a private method which allows me to simulate a drag/drop event for any of the items that the player can move around. For the dragging I am actually leaving the view that they touched where it is and creating a new ImageView with and setting the drawable to the drawingCache from the touched view, then moving this newly created ImageView around the screen following their finger. When you release your

问题 This question already has answers here : NullPointerException with autoboxing in ternary expression (4 answers) Closed 3 years ago . I like to use the ternary conditional expression in java programming, but I experienced an issue : The following code is a small example, but it shows the problem that I have found. public class Example { public Example() { Double x = 0.0; A a = new A(); x = a == null ? 0.0 : a.getY(); // Happens on this line System.out.println(x); } class A { Double y = null;

问题 In Kotlin you can create a data class : data class CountriesResponse( val count: Int, val countries: List<Country>, val error: String) Then you can use it to parse a JSON, for instance, "{n: 10}". In this case you will have an object val countries: CountriesResponse , received from Retrofit , Fuel or Gson , that contains these values: count = 0, countries = null, error = null . In Kotlin + Gson - How to get an emptyList when null for data class you can see another example. When you later try

问题 Photo capture Intent causes NullPointerException on Samsung phones only. Implementation below. final Button capture = (Button)findViewById(R.id.capture_button); capture.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub Intent cameraIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); startActivityForResult(cameraIntent, CAMERA_PIC_REQUEST); } }); protected void onActivityResult(int requestCode, int resultCode, Intent data) {

问题 I'm trying to open a FileChooser with this code: package back_end.controllers; import javafx.fxml.FXML; import javafx.fxml.Initializable; import javafx.scene.control.Button; import javafx.scene.control.ListView; import javafx.scene.layout.BorderPane; import javafx.stage.FileChooser; import java.io.File; import java.net.URL; import java.util.ResourceBundle; /** * Created by Quinn McHugh on 4/15/2014. */ public class StartScreen_Controller implements Initializable { @FXML private ListView