Class NullPointerException
java.lang.Object
java.lang.Throwable
java.lang.Exception
java.lang.RuntimeException
java.lang.NullPointerException
- All Implemented Interfaces:
Serializable
Thrown when an application attempts to use
null in a
case where an object is required. These include:
- Calling the instance method of a
nullobject. - Accessing or modifying the field of a
nullobject. - Taking the length of
nullas if it were an array. - Accessing or modifying the slots of
nullas if it were an array. - Throwing
nullas if it were aThrowablevalue.
Applications should throw instances of this class to indicate
other illegal uses of the null object.
NullPointerException objects may be constructed by the
virtual machine as if suppression were disabled and/or the
stack trace was not writable.
- Since:
- 1.0
- See Also:
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Constructor Summary
ConstructorsConstructorDescriptionConstructs aNullPointerExceptionwith no detail message.Constructs aNullPointerExceptionwith the specified detail message. -
Method Summary
Modifier and TypeMethodDescriptionReturns the detail message string of this throwable.Methods declared in class java.lang.Throwable
addSuppressed, fillInStackTrace, getCause, getLocalizedMessage, getStackTrace, getSuppressed, initCause, printStackTrace, printStackTrace, printStackTrace, setStackTrace, toString
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Constructor Details
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NullPointerException
public NullPointerException()Constructs aNullPointerExceptionwith no detail message. -
NullPointerException
Constructs aNullPointerExceptionwith the specified detail message.- Parameters:
s- the detail message.
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Method Details
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getMessage
Returns the detail message string of this throwable.If a non-null message was supplied in a constructor it is returned. Otherwise, an implementation specific message or
nullis returned.- Overrides:
getMessagein classThrowable- Implementation Note:
- If no explicit message was passed to the constructor, and as long as certain internal information is available, a verbose description of the null reference is returned. The internal information is not available in deserialized NullPointerExceptions.
- Returns:
- the detail message string, which may be
null.
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