Class NullPointerException

java.lang.Object

java.lang.Throwable

java.lang.Exception

java.lang.RuntimeException

java.lang.NullPointerException

All Implemented Interfaces:

Serializable

public class NullPointerException
extends RuntimeException

Thrown when an application attempts to use null in a case where an object is required. These include:

• Calling the instance method of a null object.
• Accessing or modifying the field of a null object.
• Taking the length of null as if it were an array.
• Accessing or modifying the slots of null as if it were an array.
• Throwing null as if it were a Throwable value.

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:

• Serialized Form

Constructor Summary

Constructors

Constructor	Description
NullPointerException()	Constructs a NullPointerException with no detail message.
NullPointerException(String s)	Constructs a NullPointerException with the specified detail message.

Method Summary

Modifier and Type	Method	Description
String	getMessage()	Returns the detail message string of this throwable.

Methods declared in class Throwable

addSuppressed, fillInStackTrace, getCause, getLocalizedMessage, getStackTrace, getSuppressed, initCause, printStackTrace, printStackTrace, printStackTrace, setStackTrace, toString

Modifier and Type	Method	Description
final void	addSuppressed(Throwable exception)	The specified exception is going to be suppressed in order to give priority to this exception (primary exception) and to be appended to the list of suppressed exceptions.
Throwable	fillInStackTrace()	Record in the receiver a walkback from the point where this message was sent.
Throwable	getCause()	Answers the cause of this Throwable, or null if there is no cause.
String	getLocalizedMessage()	Answers the extra information message which was provided when the throwable was created.
StackTraceElement[]	getStackTrace()	Answers an array of StackTraceElement.
final Throwable[]	getSuppressed()	Returns an array of exceptions suppressed, typically by the automatically generated code from the try-with-resources statement, in order to give priority to this exception (primary exception).
Throwable	initCause(Throwable throwable)	Initialize the cause of the receiver.
void	printStackTrace()	Outputs a printable representation of the receiver's walkback on the System.err stream.
void	printStackTrace(PrintStream err)	Outputs a printable representation of the receiver's walkback on the stream specified by the argument.
void	printStackTrace(PrintWriter err)	Outputs a printable representation of the receiver's walkback on the writer specified by the argument.
void	setStackTrace(StackTraceElement[] trace)	Sets the array of StackTraceElements.
String	toString()	Answers a string containing a concise, human-readable description of the receiver.

Methods declared in class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Modifier and Type	Method	Description
protected Object	clone()	Answers a new instance of the same class as the receiver, whose slots have been filled in with the values in the slots of the receiver.
boolean	equals(Object o)	Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison.
protected void	finalize()	Deprecated, for removal: This API element is subject to removal in a future version. May cause performance issues, deadlocks and hangs.
final Class<? extends Object>	getClass()	Answers the unique instance of java.lang.Class which represents the class of the receiver.
int	hashCode()	Answers an integer hash code for the receiver.
final void	notify()	Causes one thread which is waiting on the receiver to be made ready to run.
final void	notifyAll()	Causes all threads which are waiting on the receiver to be made ready to run.
final void	wait()	Causes the thread which sent this message to be made not ready to run pending some change in the receiver (as indicated by notify or notifyAll).
final void	wait(long time)	Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.
final void	wait(long time, int frac)	Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.

Constructor Details

NullPointerException

public NullPointerException()

Constructs a NullPointerException with no detail message.

NullPointerException

public NullPointerException(String s)

Constructs a NullPointerException with the specified detail message.

Parameters:

s - the detail message.

Method Details

getMessage

public String 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 null is returned.

Overrides:

getMessage in class Throwable

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.