nullpointerexception

问题 Closed . This question is opinion-based. It is not currently accepting answers. Want to improve this question? Update the question so it can be answered with facts and citations by editing this post. Closed 3 years ago . I have a simple setter method for a property and null is not appropriate for this particular property. I have always been torn in this situation: should I throw an IllegalArgumentException, or a NullPointerException? From the javadocs, both seem appropriate. Is there some

问题 This question already has answers here : What is a NullPointerException, and how do I fix it? (12 answers) Closed 5 months ago . I have a node in firebase database that I want to retrieve and put it in a spinner I made array list then looped through data snapshot but still give nullPointerException I stored the value of the child in firebase using push method I tried everything but it didn't work Model class public class Purpose { private String name; public Purpose(){ } public Purpose(String

问题 I have been trying to get a Facebook Login (alongside G+ log in) working on my app. G+ works fine, and now I've decided to add Facebook integration. I have the app ID from facebook, and have provided that in the manifest as so: <meta-data android:name="com.facebook.skd.ApplicationId" android:value="@string/app_id" /> Here is the string resource: <string name="app_id">000000000000000</string> And here is my login activity code, with censors on the appropriate information. I do not understand

问题 I am a beginner. Stuck on this NullPointerException. This is a simple program of buttons. As soon as i run as android application, the project opens and immediately gets closed by displaying unfortunately my app has stopped. 04-15 17:40:05.656: D/AndroidRuntime(599): Shutting down VM 04-15 17:40:05.656: W/dalvikvm(599): threadid=1: thread exiting with uncaught exception (group=0xb2adcd58) 04-15 17:40:05.666: E/AndroidRuntime(599): FATAL EXCEPTION: main 04-15 17:40:05.666: E/AndroidRuntime(599

问题 When I try to use this piece of code: students.add(new Student("John","1", 3)); students.add(new Student("Chris","2", 2)); NatTable table = createTable(shell, students); table.refresh(); NullPointerException appears, maybe it is because something is wrong with getters in Student class or maybe in generating the table. Also one of the messages when this problem appears is ReflectiveColumnPropertyAccessor.getDataValue. Also I need to fix ColumnGroup in NatTable to display many exams properly.

问题 I have a very simple app which isn't starting correctly. The app should load a splashscreen, and then the main app. For some reason it's now not working - Logcat: 02-08 13:30:41.846: E/AndroidRuntime(275): Uncaught handler: thread main exiting due to uncaught exception 02-08 13:30:41.865: E/AndroidRuntime(275): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.KES.GApps/com.KES.GApps.Splashscreen}: java.lang.NullPointerException 02-08 13:30:41.865: E/AndroidRuntime(275):

问题 I wonder if here is someone who can help me investigate a weird (at least for me ) behaviour of Spring. I am actually implementing changes to my project. After launching my code I get a good old NullPointer Exception. But the problem is Spring does not specifies where this error occurs. I get only some weird info about org.hibernate.tuple.entity.PojoEntityTuplizer and javaassist.proxy.ProxyFactory.CreateClass . The code is little bit complex to display here so i will provide you with my

问题 This question already has answers here : What is a NullPointerException, and how do I fix it? (12 answers) Closed 3 years ago . Note: This is intended as a canonical question for a commonly seen problem here on Stack Overflow. My Android app crashed. I checked the stacktrace from the logcat and found that the cause is a NullPointerException at the line myEditText.setText(myString); What is the problem and how do I fix it? 回答1: Please provide more detail about your code. I think you didn't

问题 When I am trying to call JPanel panel2 of Panel2 class on triggering of action event from Next JButton of Panel1 class, I am getting NullPointerException. How to resolve this? plzz help. public class PanelEventTest { /** * @param args */ JFrame frame; void originalFrame() { frame = new JFrame(); frame.setSize(500, 300); frame.setVisible(true); frame.setLayout(new FlowLayout()); frame.add(new TestPanel1().panel1()); frame.add(new TestPanel2().panel2()); } public static void main(String[] args)

问题 This question already has answers here : What is a NullPointerException, and how do I fix it? (12 answers) Closed 2 years ago . So my MainActivity was able to start my second activity from a btn click fine. Now on my second activity, I have a drag and drop type game where what I want is one the correct image was dropped, I want it to start a 3rd Activity but I am getting a java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Context.getPackageName