I have a fragment in MainActivity and try to setText in fragment, but when I try to do it I get Null Pointer Exception. I checked spelling but it seems okay. I debug app and check these variables but it doesnt seem they are null.    The exception appear in first line of clearText() method.   @Override     public View onCreateView(LayoutInflater inflater, ViewGroup container,                              Bundle savedInstanceState) {         v = inflater.inflate(R.layout.fragment_sun, container, false);          sunRiseTime = v.findViewById(R.id.sunRiseTime);         sunRiseAzimuth = v.findViewById(R.id.sunRiseAzimuth);         sunSetTime = v.findViewById(R.id.sunSetTime);         sunSetAzimuth = v.findViewById(R.id.sunSetAzimuth);         duskTime = v.findViewById(R.id.duskTime);         dawnTime = v.findViewById(R.id.dawnTime);          return v;     }  private void clearText(){         sunSetTime.setText("");         sunSetAzimuth.setText("");         sunRiseTime.setText("");         sunRiseAzimuth.setText("");         duskTime.setText("");         dawnTime.setText("");     }   The error  Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference                                                        at com.example.mariusz.astroweather.SunFragment.clearText(SunFragment.java:99)
129
What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?
35127
The cucumber feature file has all steps highlighted in yellow and warning is shown as step does not have matching glue code, When I try to run the project as maven test, I am getting null pointer exception for all steps. [Feature[Steps  Test Runner class: package com.vtiger.CucumberFramework.testRunner;  import org.junit.runner.RunWith;  import io.cucumber.junit.Cucumber; import io.cucumber.junit.CucumberOptions;  @RunWith(Cucumber.class) @CucumberOptions(                 features = &quot;classpath:features&quot;,                 glue = {&quot;com.vtiger.CucumberFramework.stepDefinitions&quot;,&quot;com.vtiger.CucumberFramework.testRunner&quot;},                  plugin = { &quot;pretty&quot;,&quot;html:target/cucumber-reports/cucumber-pretty&quot;,                             &quot;json:target/cucumber-reports/CucumberTestReport.json&quot;,                            &quot;rerun:target/cucumber-reports/rerun.txt&quot; },                 monochrome = true)  public class TestRunner {  }
65166
It seems like my code works to check for null if I do  if ($tx)    or   if (isset($tx))   why would I do the second one when it's harder to write?
38779
I'm new to Apex and development in general... So, I'm playing around coding and doing some badges in Trailhead. I created a small piece of code, as below, and have no actual use: public class GenderIdentifier {     public void DetermineGender(String Gender){                 if (Gender == 'Man'){             Gender = 'Male';             } else {             Gender = 'Female';         }            } }  If I make the method 'non-static' it works, and I can see it working fine executing as a anonymous block. If I make it static, I can't execute the anonymous block, as I get an Error like:  Non static method cannot be referenced from a static context: void GenderIdentifier.DetermineGender(String)  What am I doing wrong? It would make sense to have a method like this as Static. I think I misunderstood the concept of static methods.
101821
while making a call from php i am getting the error      Attempt to de-reference a null object Class.Demo.Insert:   What is problem in my webservice?  global class Ctest{     global class RequestClass{         webservice String accName;     }      webservice static void   cInsert(RequestClass req){         Account a1 = new Account();         a1.Name = req.accName;         insert a1;     } }   And Our Php Code Is  require_once('salesforceAPI/soapclient/SforceEnterpriseClient.php'); require_once('salesforceAPI/soapclient/SforceHeaderOptions.php');  $sfdc = new SforceEnterpriseClient(); $SoapClient = $sfdc-&gt;createConnection('enterprise.wsdl.xml');  $loginResult = false;  $loginResult = $sfdc-&gt;login(USER, PASSWORD . SECURITY_KEY);  $parsedURL = parse_url($sfdc-&gt;getLocation()); define("_SFDC_SERVER_", substr($parsedURL['host'], 0, strpos($parsedURL['host'], '.'))); define("_WS_NAME_", 'salesforceAPI/Ctest'); define("_WS_WSDL_", _WS_NAME_ . '.xml'); define("_WS_ENDPOINT_", 'https://' . _SFDC_SERVER_ . '.salesforce.com/services/wsdl/class/' . _WS_NAME_); define("_WS_NAMESPACE_", 'http://soap.sforce.com/schemas/class/' . _WS_NAME_);  $client = new SoapClient(_WS_WSDL_); $sforce_header = new SoapHeader(_WS_NAMESPACE_, "SessionHeader", array("sessionId" =&gt; $sfdc-&gt;getSessionId())); $client-&gt;__setSoapHeaders(array($sforce_header));  $method = $client-&gt;__getFunctions();  $wsParams = array('accName' =&gt; 'XXXXXXX');  $client-&gt;cInsert($wsParams)
107801
I posted the code below to the Sun developers forum since I thought it was erroring (the true error was before this code was even hit).  One of the responses I got said it would not work and to throw it away.  But it is actually working.  It might not be the best code (I am new to Java) but is there something inherently "wrong" with it?   =============  CODE:   private static void ImportFromCsvToAccessTable(String mdbFilePath, String accessTableName  , String csvDirPath , String csvFileName ) throws ClassNotFoundException, SQLException {      Connection msConn = getDestinationConnection(mdbFilePath);     try{          String strSQL = "SELECT * INTO " + accessTableName + " FROM [Text;HDR=YES;DATABASE=" + csvDirPath + ";].[" + csvFileName + "]";         PreparedStatement selectPrepSt = msConn.prepareStatement(strSQL );         boolean result = selectPrepSt.execute();                 System.out.println( "result = " + result );      } catch(Exception e) {         System.out.println(e);     } finally {         msConn.close();     } }
38112
Here's the scenario...    if (entry.Properties["something"].Value != null)   attribs.something = entry.Properties["something"].Value.ToString();   While effective and working correctly, this looks ugly to me.  If I don't check for a null before performing the ToString() then it throws an exception if the property was null.  Is there a better way to handle this scenario?  Much appreciated!
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Why does it (apparently) make a difference whether I pass null as an argument directly, or pass an Object that I assigned the value null?  Object testVal = null; test.foo(testVal);    // dispatched to foo(Object) // test.foo(null);    // compilation problem -&gt; "The method foo(String) is ambiguous"     public void foo(String arg) { // More-specific     System.out.println("foo(String)"); }  public void foo(Object arg) { // Generic     System.out.println("foo(Object)"); }   In other words, why is the (commented-out) second call to foo(...) not dispatched to foo(Object)?  Update: I use Java 1.6. I could compile Hemal's code without problems, but mine still doesn't compile. The only difference I see is that Hemal's methods are static while mine are not. But I really don't see why this should make a difference...?  Update 2: Solved. I had another method foo(Runnable) in my class, so the dispatcher couldn't unambiguously select the single most specific method. (See my comment in Hemal's second answer.) Thanks everyone for your help.
86277
Why does the following code sometimes causes an Exception with the contents "CLIPBRD_E_CANT_OPEN":  Clipboard.SetText(str);   This usually occurs the first time the Clipboard is used in the application and not after that.
11494
App version 1.0.27  If you the notification pane and click on the loading icon while it's spinning, the app will cause the app to crash.  03-26 22:51:08.331 E/AndroidRuntime(5927): FATAL EXCEPTION: main 03-26 22:51:08.331 E/AndroidRuntime(5927): java.lang.ArrayIndexOutOfBoundsException: length=0; index=-1 03-26 22:51:08.331 E/AndroidRuntime(5927): at java.util.ArrayList.get(ArrayList.java:310) 03-26 22:51:08.331 E/AndroidRuntime(5927): at com.stackexchange.marvin.ui.BaseActivity$3.onItemClick(BaseActivity.java:266) 03-26 22:51:08.331 E/AndroidRuntime(5927): at android.widget.AdapterView.performItemClick(AdapterView.java:298) 03-26 22:51:08.331 E/AndroidRuntime(5927): at android.widget.AbsListView.performItemClick(AbsListView.java:1100) 03-26 22:51:08.331 E/AndroidRuntime(5927): at android.widget.AbsListView$PerformClick.run(AbsListView.java:2788) 03-26 22:51:08.331 E/AndroidRuntime(5927): at android.widget.AbsListView$1.run(AbsListView.java:3463) 03-26 22:51:08.331 E/AndroidRuntime(5927): at android.os.Handler.handleCallback(Handler.java:730) 03-26 22:51:08.331 E/AndroidRuntime(5927): at android.os.Handler.dispatchMessage(Handler.java:92) 03-26 22:51:08.331 E/AndroidRuntime(5927): at android.os.Looper.loop(Looper.java:137) 03-26 22:51:08.331 E/AndroidRuntime(5927): at android.app.ActivityThread.main(ActivityThread.java:5103) 03-26 22:51:08.331 E/AndroidRuntime(5927): at java.lang.reflect.Method.invokeNative(Native Method) 03-26 22:51:08.331 E/AndroidRuntime(5927): at java.lang.reflect.Method.invoke(Method.java:525) 03-26 22:51:08.331 E/AndroidRuntime(5927): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737) 03-26 22:51:08.331 E/AndroidRuntime(5927): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 03-26 22:51:08.331 E/AndroidRuntime(5927): at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:126) 03-26 22:51:08.331 E/AndroidRuntime(5927): at dalvik.system.NativeStart.main(Native Method)   (Think I should calm down on finding bugs for a little while? :P)
8224
Since many users are facing the NullReferenceException: Object reference not set to an instance of an object error in Unity, I thought that it would be a good idea to gather from multiple source some explanation and ways to fix this error.  Symptoms I am getting the error below appearing in my console, what does it mean and how do I fix it?  NullReferenceException: Object reference not set to an instance of an object
72722
getRealPath() is returning the actual path in the local system, but returns null when deployed with a .war file.  &lt;%@ page import="java.io.*" %&gt; &lt;%@ page contentType="text/html;charset=ISO-8859-1" %&gt;  &lt;% int iLf = 10; char cLf = (char)iLf; String a= application.getResource("/"); //String myfile = application.getRealPath("/")+ "generate.xml"; //String myfile = request.getContextPath()+"generate.xml"; //String myfile = request.getRealPath("/")+"generate.xml";  out.println(myfile);     File outputFile = new File(myfile); outputFile.createNewFile(); FileWriter outfile = new FileWriter(outputFile); outfile.write(" &lt;?xml version='1.0' encoding='UTF-8'?&gt; "+cLf); outfile.write(" &lt;playlist version='1' xmlns = 'http://xspf.org/ns/0/' &gt; " +cLf); outfile.write(" &lt;title&gt;My Band Rocks Your Socks&lt;/title&gt; "+cLf);  outfile.write("&lt;trackList&gt;"+cLf);  %&gt;  &lt;%! String[] sports; %&gt;  &lt;%     sports = request.getParameterValues("sports");      out.println("&lt;html&gt;&lt;body&gt;&lt;h1&gt;hello&lt;/h1&gt;&lt;/body&gt;&lt;/html&gt;");      if (sports != null)     {           for (int i = 0; i &lt; sports.length; i++)          {                // outfile.writeln (sports[i]);                String total=sports[i];               String[] sa=total.split("[,]");               // String[] sub=new String();               outfile.write("&lt;track&gt;"+cLf);               for (int j=0;j&lt;sa.length;j++)               {                 // outfile.writeln(sa[j]);                 // outfile.writeln("sa["+j+"]="+sa[j]);                 if( j == 0)                 {                      outfile.write("&lt;location&gt;" + sa[0] +"&lt;/location&gt;"+cLf);                  }                 else if (j == 1)                      {                         outfile.write("&lt;image&gt;" + sa[1] +"&lt;/image&gt;"+cLf);                       }                      else if( j==2)                           {                             outfile.write("&lt;title&gt;" + sa[2] +"&lt;/title&gt;"+cLf);                           }                 }// end of inner for loop()                       outfile.write("&lt;/track&gt;"+cLf);          //outfile.writeln();       }// end of outer for()     }      //else outfile.writeln ("&lt;b&gt;none&lt;b&gt;");    outfile.write(" &lt;/trackList&gt; "+cLf);   outfile.write(" &lt;/playlist&gt; "+cLf);   outfile.close();    %&gt; &lt;object type="application/x-shockwave-flash" width="400" height="170"           data="xspf_player.swf?playlist_url=generate.xml"&gt;           &lt;param name="movie" value="xspf_player.swf?playlist_url=generate.xml" /&gt;  &lt;/object&gt;   Can anyone provide me with an alternative for this? It would be very helpful if you showed some sample code too.
21733
EmployeeNumber = string.IsNullOrEmpty(employeeNumberTextBox.Text)     ? null     : Convert.ToInt32(employeeNumberTextBox.Text),  I often find myself wanting to do things like this (EmployeeNumber is a Nullable&lt;int&gt; as it's a property on a LINQ-to-SQL dbml object where the column allows NULL values).  Unfortunately, the compiler feels that  There is no implicit conversion between 'null' and 'int'  even though both types would be valid in an assignment operation to a nullable int on their own. Using the null coalescing operator is not an option as far as I can see because of the inline conversion that needs to happen on the .Text string if it's not null. As far as I know the only way to do this is to use an if statement and/or assign it in two steps.  In this particular case I find that very frustrating because I wanted to use the object initializer syntax and this assignment would be in the initialization block... Does anyone know a more elegant solution?
28022
I know that it does consider ' ' as NULL, but that doesn't do much to tell me why this is the case.  As I understand the SQL specifications, ' ' is not the same as NULL -- one is a valid datum, and the other is indicating the absence of that same information.  Feel free to speculate, but please indicate if that's the case.  If there's anyone from Oracle who can comment on it, that'd be fantastic!
103112
When and why would somebody do the following:  doSomething( (MyClass) null );   Have you ever done this? Could you please share your experience?
34848
I used to use the implicit call of toString when wanting some debug info about an object, because in case of the object is null it does not throw an Exception.  For instance:    System.out.println("obj: "+obj);   instead of:  System.out.println("obj: "+obj.toString());   Is there any difference apart from the null case? Can the latter case work, when the former does not?  Edit: What exactly is done, in case of the implicit call?
58461
Consider the code:  PreparedStatement ps = null; ResultSet rs = null; try {   ps = conn.createStatement(myQueryString);   rs = ps.executeQuery();   // process the results... } catch (java.sql.SQLException e) {   log.error("an error!", e);   throw new MyAppException("I'm sorry. Your query did not work."); } finally {   ps.close();   rs.close(); }   The above does not compile, because both PreparedStatement.close() and ResultSet.close() throw a java.sql.SQLException.  So do I add a try/catch block to the finally clause?  Or move the close statements into the try clause?  Or just not bother calling close?