How to solve java.lang.NullPointerException error?
Solution 1
A NullPointerException means that one of the variables you are passing is null, but the code tries to use it like it is not.
For example, If I do this:
Integer myInteger = null;
int n = myInteger.intValue();
The code tries to grab the intValue of myInteger, but since it is null, it does not have one: a null pointer exception happens.
What this means is that your getTask method is expecting something that is not a null, but you are passing a null. Figure out what getTask needs and pass what it wants!
Solution 2
This error occures when you try to refer to a null object instance. I can`t tell you what causes this error by your given information, but you can debug it easily in your IDE. I strongly recommend you that use exception handling to avoid unexpected program behavior.
Solution 3
Just a shot in the dark(since you did not share the compiler
initialization code with us): the way you retrieve the compiler
causes the issue. Point your JRE to be inside the JDK as unlike jdk, jre does not provide any tools hence, results in NPE
.
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Justin k
Updated on July 09, 2022Comments
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Justin k almost 2 years
When I run my Java program, it gives me an error on this line
compiler.getTask(null, null, new DiagnosticCollector<JavaFileObject>(), null, null, compilationUnits);
Error I am getting is:
Exception in thread "main" java.lang.NullPointerException at AnotherClassLoader.loadClass(test.java:58) at test.main(test.java:30) at Main.main(Main.java:68)
Can you please tell me how can I solve this error?
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kentcdodds almost 12 yearsPlease include a SSCCE if you want any help. We can't do much without a SSCCE. Thanks. Oh, and consider changing the title of your question to something a little more descriptive please.
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Amokrane Chentir almost 12 yearsThe stacktrace gives you the exact line where the
NullPointerException
occurs. You just have to understand why you got that and fix it... -
Admin almost 12 yearsIt is solved by identifying the problem and then correcting the identified problem. NPEs [should] only occur in the case of:
someNullExpression.someMember
. That is, thenull
value must be the target expression of a member/method for this exception to naturally occur. In the posted example there is only one expression that can meet this requirement. (Hint: what does thecompiler
variable evaluate to?) -
Jeremy almost 12 yearsRelax, guys. He is asking what a null pointer exception is.
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Jeremy almost 12 years@pst Since the exception is in "AnotherClassLoader.loadClass", doesn't that imply the null pointer is further downstream? If compiler was null it would just be a null pointer exception right there in main.
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Admin almost 12 years@Jeremy It's something on line 58 of test.java... I don't think a real classloader can throw an NPE out like that, but I'm not sure now.
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user2856095 over 10 years
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ArifMustafa about 6 years
@SuppressWarnings("null") public void WelcomeToNPE_MethodLand() throws NullPointerException { Object NPE_Wisher = null; try { if (!"Java".equals(NPE_Wisher)) System.out.println("Am I executed....? - User"); if (NPE_Wisher.equals(null)) //Here NPE_Wisher object will call mrNPE_Obj System.out.println("Shall I good till here...!"); } catch (NullPointerException mrNPE_Obj) { System.out.println("You already had understand me... - NullPointerException\n"); throw mrNPE_Obj; } }
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